Date   
Re: #ubitx Re: Ubitx only on preorder now #ubitx

Art Howard
 

109 ground shipping ?

On 1 Jan 2018 1:51 pm, "chris gress" <Chrisg0wfh@...> wrote:
I ordered mine last night and got the HF signals email today I an on pre order got it for the 109 dollar price so I am happy 
Chris G0WFH 

On 1 Jan 2018 19:16, "B C" <k9wis@...> wrote:
Just got an email from hf signals acknowledging my order and payment on Dec 14th, two weeks ago...No indication of when they will ship..
Brian K9WIS



Re: Selecting the correct BFO frequency

Kerr Smith
 

Thanks for the replies - will adjust the BFO so it sits at 20dB down the edge of the filter - I will try lowering its frequency first and see how it goes, I tried changing the capacitance in series with the crystal as a quick test and this did alter its frequency so I will look in to this more tomorrow.

The circuit for the BFO I am using is the one shown in figure 18 of the following site:

http://www.nutsvolts.com/magazine/article/bipolar_transistor_cookbook_part_5

This receiver is planned to be a completely handmade version - my last creation was a Bitx20 using a si5351 and this works very well, it has a display screen, rotary encoder tuning as well as memory - I spent far longer on writing the software than in making the actual circuit (every time I thought I was finished I had another idea for an extra feature).

For this receiver I am trying to design it as much as possible by hand so I can learn more about how to do this. I only have a few bits left such as the second mixer, another RF amplifier and the audio amplifier - I already have working versions of the mixer and tuned RF amplifier so these just need duplicating.

Just to clarify - will it matter if I decide to put the BFO above or below the center frequency of the crystal filter - this is just going to be a receiver for 40m, there will be no transmitting circuits?

Re: #ubitx Re: Ubitx only on preorder now #ubitx

Andrew Farkas <afarkas@...>
 

I ordered mine on the 12th of December and it's due here in VA3 land on Jan 3rd. I ordered it and had it sent DHL for Christmas and later on found out they were previously sold out. 
If I'd known they were sold out I would've just had it sent India Post since I'll probably get dinged for the duty coming into Canada. I'll take the hit though for this uBitx. I was going to buy an FT817ND last year. I figure I'm saving myself at least $700 to $1000 Canadian.
Works for me! 
Thank you Mr. Ashar Farhan!

On Jan 1, 2018 2:51 PM, chris gress <Chrisg0wfh@...> wrote:
I ordered mine last night and got the HF signals email today I an on pre order got it for the 109 dollar price so I am happy 
Chris G0WFH 

On 1 Jan 2018 19:16, "B C" <k9wis@...> wrote:
Just got an email from hf signals acknowledging my order and payment on Dec 14th, two weeks ago...No indication of when they will ship..
Brian K9WIS




Re: Tell me your favorite uBitx mods

K5ESS
 

There are many 3.3v 16 X 2 displays advertised on Ebay.  Practically giving this one away.

https://www.ebay.com/itm/DC-3-3V-HD44780-1602-LCD-Display-Module-16x2-Character-LCM-Blue-Blacklight-NEW-/162222360139?hash=item25c534c64b

Mike

K5ESS

 

From: BITX20@groups.io [mailto:BITX20@groups.io] On Behalf Of Diver Martin
Sent: Monday, January 1, 2018 3:33 PM
To: BITX20@groups.io
Subject: Re: [BITX20] Tell me your favorite uBitx mods

 

The Teensy3.2 is a great little uC, I've used it in a lot of other projects.  Removing the leonardo and replacing with a Teensy would yield a price delta of about ~+$15, as the ATMega32U4 is about $4, popcorn components another $1, and the teensy3.2 is $20.  The downside to a teensy3.2 in this case is that it'll have to require some level shifting for the display and a few other things I think maybe, as it's a 3.3V output IO. (Unless the display and other things can tolerate 3.3V, which I haven't looked into)

 

On Mon, Jan 1, 2018 at 3:21 AM, gerrykav via Groups.Io <gerrykav@...> wrote:

I am planning on adding this audio filter/DSP project to mine... when I get it.

https://gi1mic.github.io/

/ Gerry



 

--

Martin Held - AE7EU

http://ae7eu.com/
-------------------------------------------------------------------------------
If there aren't any questions, then what is there to learn?

Re: Tell me your favorite uBitx mods

Diver Martin <diver.martin@...>
 

Figured out what my plan was on that front.  I want to re-use as much of the raduino as possible, so one thing I did to make my life easier was to use a 74HC595 shift register, frees up IO's, and uses ones I've already got to level shift up to 5V for the IO expanders (the relays are all 5V that I'm using / have already designed in).  This way, the stock display module that comes with the raduino can be used.

Though, that is pretty dang cheap :)

On Mon, Jan 1, 2018 at 3:00 PM, K5ESS <k5ess.nothdurft@...> wrote:

There are many 3.3v 16 X 2 displays advertised on Ebay.  Practically giving this one away.

https://www.ebay.com/itm/DC-3-3V-HD44780-1602-LCD-Display-Module-16x2-Character-LCM-Blue-Blacklight-NEW-/162222360139?hash=item25c534c64b

Mike

K5ESS

 

From: BITX20@groups.io [mailto:BITX20@groups.io] On Behalf Of Diver Martin
Sent: Monday, January 1, 2018 3:33 PM
To: BITX20@groups.io
Subject: Re: [BITX20] Tell me your favorite uBitx mods

 

The Teensy3.2 is a great little uC, I've used it in a lot of other projects.  Removing the leonardo and replacing with a Teensy would yield a price delta of about ~+$15, as the ATMega32U4 is about $4, popcorn components another $1, and the teensy3.2 is $20.  The downside to a teensy3.2 in this case is that it'll have to require some level shifting for the display and a few other things I think maybe, as it's a 3.3V output IO. (Unless the display and other things can tolerate 3.3V, which I haven't looked into)

 

On Mon, Jan 1, 2018 at 3:21 AM, gerrykav via Groups.Io <gerrykav=yahoo.co.uk@groups.io> wrote:

I am planning on adding this audio filter/DSP project to mine... when I get it.

https://gi1mic.github.io/

/ Gerry



 

--

Martin Held - AE7EU

http://ae7eu.com/
-------------------------------------------------------------------------------
If there aren't any questions, then what is there to learn?




--
Martin Held - AE7EU
http://ae7eu.com/
-------------------------------------------------------------------------------
If there aren't any questions, then what is there to learn?

#ubitx Power output on 40 / 80 m with high current levels #ubitx

Alex - PA1FOX
 

Hi all,

I'm working on my uBitx which is completely homybuilt, so not the currently sold PCB version. By building it from scratch you encounter a lot of interesting things and learn a lot about it. Receiving of the rig is very good now but I am struggling with the TX. When aligned for output power of 8 watts, using a sine wave generator and full modulation level, the rig draws about 3,5 amps of current on 40M. At 80M, power output increases to about 12 watts, but current jumps up to around 4 amps. Sometimes my IRF's get killed at that level. There's now way so far I've got it set to say 8 watts with less than 2 amps of current. Things I've done so far are:

Play around with the HF power gain pot RV1 in combination with more audio drive level
Play around with the IRF's bias adjustment. Setting it too high will give a current thermal runaway and a fried IRF within a second. Careful with that...
Output toroids of the IRF balance, changed the windings bifilair, trifilair en more in both directions, so in fact play around with the output impedance with the IRF's see. The trifilair original option seems to be the best bet, but with these high current values. Toroid is a 37-10 with 7 windings trifilair.
Changed the emitter resistances on the 2N2219 to decrease the input power.

I've measured the LPF and it has a cutoff at 7300 KHz so that should be fine.
Testing done at 12volts, when at 13,8 volts, the output power and IRF amp values increase dramatically (got over 16 watts of RF) but this often kills one of the IRF's. No way I would keep the IRF's alive on 24 volts.
I don't have the LPF's for the higher bands in place yet, but it seems that at 20m and higher the overall gain of the TX chain decreases. When measured WITHOUT LPF (yes on dummy load, for sure) output power decreases to less than a single watt... This could also be an effect of the bidirectional part of the TX chain where the gain decreases with higher frequencies. For now I'm concentrating on the difference between the behaviour at 40 and 80 meters.

Could it be I am just using a wrong brand of IRF's? I have a load coming in from a second supplier to check.
Any other ideas? I have got rechargeable batteries built into my rig and they would last much longer if I could keep the total peak current below 2 amps.

Oh by the way, I've got a very large cooling heat sink and never got it really hot, just 'warm' 

Lovely experimental rig!

73, Alex
PA1FOX

Re: #ubitx Re: Ubitx only on preorder now #ubitx

Ken
 

Andrew

You shouldn't be dinged for customs as we have an exemption up to a limit.

73

Ken VA3ABN

On Mon, Jan 1, 2018 at 5:58 PM, Andrew Farkas <afarkas@...> wrote:
I ordered mine on the 12th of December and it's due here in VA3 land on Jan 3rd. I ordered it and had it sent DHL for Christmas and later on found out they were previously sold out. 
If I'd known they were sold out I would've just had it sent India Post since I'll probably get dinged for the duty coming into Canada. I'll take the hit though for this uBitx. I was going to buy an FT817ND last year. I figure I'm saving myself at least $700 to $1000 Canadian.
Works for me! 
Thank you Mr. Ashar Farhan!

On Jan 1, 2018 2:51 PM, chris gress <Chrisg0wfh@...> wrote:
I ordered mine last night and got the HF signals email today I an on pre order got it for the 109 dollar price so I am happy 
Chris G0WFH 

On 1 Jan 2018 19:16, "B C" <k9wis@...> wrote:
Just got an email from hf signals acknowledging my order and payment on Dec 14th, two weeks ago...No indication of when they will ship..
Brian K9WIS





Re: #ubitx Re: Ubitx only on preorder now #ubitx

John Miller
 

I ordered one the 15th, I have no clue when it will come in. I was hoping for Christmas but knew it wasn’t likely. Oh well, gathering a lot of good info on this list and looking forward to when it does actually get here.

 

From: BITX20@groups.io [mailto:BITX20@groups.io] On Behalf Of Ken
Sent: Monday, January 01, 2018 6:45 PM
To: BITX20@groups.io
Subject: Re: [BITX20] #ubitx Re: Ubitx only on preorder now

 

Andrew

 

You shouldn't be dinged for customs as we have an exemption up to a limit.

 

73

 

Ken VA3ABN

 

On Mon, Jan 1, 2018 at 5:58 PM, Andrew Farkas <afarkas@...> wrote:

I ordered mine on the 12th of December and it's due here in VA3 land on Jan 3rd. I ordered it and had it sent DHL for Christmas and later on found out they were previously sold out. 

If I'd known they were sold out I would've just had it sent India Post since I'll probably get dinged for the duty coming into Canada. I'll take the hit though for this uBitx. I was going to buy an FT817ND last year. I figure I'm saving myself at least $700 to $1000 Canadian.

Works for me! 

Thank you Mr. Ashar Farhan!

 

On Jan 1, 2018 2:51 PM, chris gress <Chrisg0wfh@...> wrote:

I ordered mine last night and got the HF signals email today I an on pre order got it for the 109 dollar price so I am happy 

Chris G0WFH 

 

On 1 Jan 2018 19:16, "B C" <k9wis@...> wrote:

Just got an email from hf signals acknowledging my order and payment on Dec 14th, two weeks ago...No indication of when they will ship..
Brian K9WIS


 

 

Re: Tell me your favorite uBitx mods

AndyH
 

On Mon, Jan 1, 2018 at 01:15 am, Dave Bottom wrote:
Hi Martin,
 
 A Second Story is a neat idea that could eliminate wiring with a suitable case that can take advantage of PCB mounted connectors.
Here's my wish list...
 
Important:
1) Well the top of my list is a really effective AGC.  This is what separates a really great rig from a really good rig.
The basic MicroBITX so reminds me of my SBE SB-33 (1966 - mobile rig) it is the audio derived AGC. 
Back in the day Collins S-Line had great (but complex) AGC that worked(s) great, but..
Nearly every Heathkit SSB rig back in the day had great AGC whether it was a tube HW-12 or a solid state HW-104.
Check out the HW-104 AGC system...
 
2) Solid CW Keying and for a paddle
 
3) USB interface to rear panel -  One big reason for this kit is to become proficient working with software.
 
4) Well if those are done an S-Meter is nice.
 
Nice to have:
4) Momentary button to toggle between VFO A and VFO B.  If you work split this is really necessary (Yes, I chase DX on QRP)
 
5) Mic Pre-Amp and Mic Gain -  I added this tonight with the PCB temporarily stuck on the rear panel (all my jacks are on the rear panel out of the way of knobs. 
It helps a little so I don't feel like I have to climb in the Mic, however a Speech Compressor might be more worthwhile.  Being able to use typical Electret Condenser Mics (e.g. ICOM radios) it needs more gain and an adjustment even if a PCB mounted internally accessible set and forget pot.
 
6) Keying interface for a Linear.  Band data and keying - This baby will drive an RF-KIT 2K+ LDMOS linear to legal limit. (when life is too short for QRP)
 
When you have nothing better to do:
7) VSWR Bridge with Display for forward/reflected power.  The tuner gets a lot simpler and an external tuner may not need power (manual tuner).
 
Oh, wait, didn't you do that one already?  LOL
 
Dave WI6R

On Sun, Dec 31, 2017 at 6:29 PM, Diver Martin <diver.martin@...> wrote:
Hello all,
 
As I'm doing a motherboard mod, I'm looking to incorporate a bunch of mods into one PCB.  Right now, what I've got going are the following:
 
* A tuner + SWR Bridge (phase detector maybe?)
* A spot for an RTL-SDR (blogV3) dongle
* AGC Modifications
* Integrating LCD and headphone/mic/BNC/Power/etc jacks into the PCB
 
Other things I've thought about, space depending:
 
*Adding in footprints for a chinese AD9850 DDS module for one of the clock signals
 
I would like to hear the top mods you've done, and what you'd love to see integrated into a motherboard PCB that fits on top of the uBitx.  Battery charger?  Battery adapter? I dunno, bring it on!  If you have a favorite AGC mod, please tell me about it, and make some suggestions as well.  This is not promising to be a cheap kit, and full of SMT, but something I might make available.
 
Happy new year,
 
--
Martin Held - AE7EU
http://ae7eu.com/
-------------------------------------------------------------------------------
If there aren't any questions, then what is there to learn?

 

 

 



 
--
73 Dave WI6R

#ubitx IRF510 concerns, different modes #ubitx

Ghericoan
 

I have yet to get my ubitx yet, as I am on the preorder list. But I was wondering if there is a way to back the power output down to five watts to save the heat stress on the IRF510s. I am looking to do digital modes like PSK31, WSPR, and possibly playing around with SSTV.

Just concerned on how to go about assembly once the unit is here because I want it to be solid for digital modes. I have already ordered spare MOSFETs, but would rather not get into the habit of replacing them.
--
----------
N5WLF, Greggory (or my nickname, Ghericoan)
General Class, Digital Radio Hobbyist

Re: #ubitx IRF510 concerns, different modes #ubitx

Gordon Gibby <ggibby@...>
 

Greggory --- it won't be nearly the problem you're thinking....


Just tone down the audio level into the mic if you want a lower power level.   With single side band, that proportionately reduces your output.    ​It is as  easy as that.    I haven't used these rigs a ton yet, but I've made multiple digital connections (WINLINK, ALE) and no problems at all with the finals.   


gordon




From: BITX20@groups.io <BITX20@groups.io> on behalf of Ghericoan <boakawizkid@...>
Sent: Monday, January 1, 2018 7:18 PM
To: BITX20@groups.io
Subject: [BITX20] #ubitx IRF510 concerns, different modes
 
I have yet to get my ubitx yet, as I am on the preorder list. But I was wondering if there is a way to back the power output down to five watts to save the heat stress on the IRF510s. I am looking to do digital modes like PSK31, WSPR, and possibly playing around with SSTV.

Just concerned on how to go about assembly once the unit is here because I want it to be solid for digital modes. I have already ordered spare MOSFETs, but would rather not get into the habit of replacing them.
--
----------
N5WLF, Greggory (or my nickname, Ghericoan)
General Class, Digital Radio Hobbyist

Re: Got Mine Built #ubitx

Terence Taylor
 

OK, here is the file to use for laser/cnc cutting of the case I made. I cut in out of 1/8" (3mm) MDF. Since that is a little too thick for the supplied  jacks, you may need to glue the jacks into the from panel or use a Forstner bit to create a recess for the retaining nuts.

Re: Selecting the correct BFO frequency

Jerry Gaffke
 

It definitely matters if the BFO is above or below the crystal filter passband.

I was talking both transmit and receive in that last post, but the math is the same regardless of which direction the signals travel.
If you want a BFO slightly lower in frequency than the crystal filter, the 10mhz crystal filter will be receiving a 10mhz USB signal.
So to compensate, must run the VFO at 17mhz, on the high side of 10mhz crystal filter, which flips things so that you will be receiving 7mhz LSB signals.
A 17mhz analog VFO is possible, but will be tricky to get stable enough.

The parallel resonant frequency of a crystal is a few khz above the series resonant frequency, that may be the key to using
a 3mhz analog VFO with your 10mhz crystal filter to receive a 7mhz LSB signal.
It is the series resonant frequency that is used by your crystal filter, and by many oscillator circuits.
So I'd fiddle around with the circuit in figure 18 of the nutsvolts.com link you posted to get a BFO above your crystal filter.
And/or look this over: http://www.robkalmeijer.nl/techniek/electronica/radiotechniek/hambladen/radcom/2001/05/page63/index.html

 


On Mon, Jan 1, 2018 at 02:54 pm, Kerr Smith wrote:
Just to clarify - will it matter if I decide to put the BFO above or below the center frequency of the crystal filter - this is just going to be a receiver for 40m, there will be no transmitting circuits?

Re: #ubitx IRF510 concerns, different modes #ubitx

Ghericoan
 

Alrighty, was just thinking about the duty cycles and such. Would make sense to just back off the input gain.
--
----------
N5WLF, Greggory (or my nickname, Ghericoan)
General Class, Digital Radio Hobbyist

Re: Tell me your favorite uBitx mods

Clark Martin
 

You save on package count with the TPIC6B595.

It’s basically an HC595 with 150 mA sink drivers.


Clark Martin
KK6ISP

On Jan 1, 2018, at 3:11 PM, Diver Martin <diver.martin@...> wrote:

Figured out what my plan was on that front.  I want to re-use as much of the raduino as possible, so one thing I did to make my life easier was to use a 74HC595 shift register, frees up IO's, and uses ones I've already got to level shift up to 5V for the IO expanders (the relays are all 5V that I'm using / have already designed in).  This way, the stock display module that comes with the raduino can be used.

Re: Tell me your favorite uBitx mods

Diver Martin <diver.martin@...>
 

So looking at the schematic, it's basically an IF amp (MC1350P, which is obsolete/harder to get, though I have gotten them from Jameco before) with a dual gate mosfet as the attenuation stage.  The rest is just a separate amplifier (Q504-509) and a detector diode (D502) feeding that gate.

What I would ultimately want to do I think is provide one input, and one out on the add-on PCB that I'm doing, and maybe cut at Q30 on the uBitx to get the RF input.  To do the mod, one would cut the trace as indicated, and then solder in some 30ga wire that goes up to the motherboard, which provides the modification.  I'm thinking Q30 is probably the best place to put the AGC, as after the 12Mhz narrow filter, there is no other amplifier, so I'm kinda limited to the 12kHz bandwidth filter to do the AGC I think.



On Mon, Jan 1, 2018 at 2:29 AM, Dave Bottom <ars.kd6az@...> wrote:
Martin,

The Heathkit SB-104/A/HW-104 has an uderly simple AGC system that works so well it was easily the easiest rig to just sit and read the mail.  Round tables with so many different strength signals and it was so pleasant to listen to.  Just a dual insulated gate FET ahead of the IF Gain and there are 8 transistors in the AGC Amplifier, Fast/Slow AGC and S-Meter output.

Schematic attached of SB-104A.

Dave

I actually had a couple of pre-amps for a hi fi project, but used for this kitsrus.com Kit 98, works, but there are simpler circuits.

Dave WI6R

On Mon, Jan 1, 2018 at 1:27 AM, Diver Martin <diver.martin@...> wrote:
Dave,

I agree with many of your points, very specifically, the AGC.  I tried listening in with my uBitx once I got the case wired up, and then promptly had my ears blown off by a nearby static pop or something.  I haven't listened to it since, and won't until I get some form of AGC, hopefully RF-derived... I am very touchy about my hearing, as it's sensitive and you only get one set of years (I wore earplugs all new years this year... hope yours was quieter).  I need to figure out the proper AGC scheme that is best, it should be reasonably easy to do.

Down the line, but a quick note:  Panel space is the biggest premium I'm dealing with. The display alone takes up 3.2" of front panel space.  Either one has to create a mezzanine board to 'stack' buttons/encoders/etc vertically, or you start going to the back panel, the side panels, etc.

1) Already covered above
2) Already in my schematic (I use a BY-1)
3) Already in my schematic
4) S-meter would have to be derived from the AGC, but I see no reason it couldn't be.  I've added in an analog pin.
4b) I have one 'undefined' front panel button.  I'd like to have more if possible... I might add in an extra MCP23S17 to expand my IO's...  (I'm nearly full on the leonardo)
5) Not sure how to implement this one, but if you've got a rough schematic to point me to of your modifications, I can probably include it.  Depends on how the wires would need to go to the PCB below, or if it's something that can just be put inline with the microphone.  Could do a microphone amplifier I suppose...  This is probably the lowest priority out of the things listed for me.
6) It's easy enough to pipe the TX line out to a relay.  I'll consider it based on panel space.
7) Yep, already in the schematic.  For now I'll probably stick to linear / non-phase detector method, but it probably wouldn't be hard to modify for a phase detector.  Just would need to focus on how to do it on the cheap instead of using an AD8307 or 8302 (Which are like $10-25 at digikey).


On Mon, Jan 1, 2018 at 1:15 AM, Dave Bottom <ars.kd6az@...> wrote:
Hi Martin,

 A Second Story is a neat idea that could eliminate wiring with a suitable case that can take advantage of PCB mounted connectors.
Here's my wish list...

Important:
1) Well the top of my list is a really effective AGC.  This is what separates a really great rig from a really good rig.
The basic MicroBITX so reminds me of my SBE SB-33 (1966 - mobile rig) it is the audio derived AGC. 
Back in the day Collins S-Line had great (but complex) AGC that worked(s) great, but..
Nearly every Heathkit SSB rig back in the day had great AGC whether it was a tube HW-12 or a solid state HW-104.
Check out the HW-104 AGC system...

2) Solid CW Keying and for a paddle

3) USB interface to rear panel -  One big reason for this kit is to become proficient working with software.

4) Well if those are done an S-Meter is nice.

Nice to have:
4) Momentary button to toggle between VFO A and VFO B.  If you work split this is really necessary (Yes, I chase DX on QRP)

5) Mic Pre-Amp and Mic Gain -  I added this tonight with the PCB temporarily stuck on the rear panel (all my jacks are on the rear panel out of the way of knobs. 
It helps a little so I don't feel like I have to climb in the Mic, however a Speech Compressor might be more worthwhile.  Being able to use typical Electret Condenser Mics (e.g. ICOM radios) it needs more gain and an adjustment even if a PCB mounted internally accessible set and forget pot.

6) Keying interface for a Linear.  Band data and keying - This baby will drive an RF-KIT 2K+ LDMOS linear to legal limit. (when life is too short for QRP)

When you have nothing better to do:
7) VSWR Bridge with Display for forward/reflected power.  The tuner gets a lot simpler and an external tuner may not need power (manual tuner).

Oh, wait, didn't you do that one already?  LOL

Dave WI6R

On Sun, Dec 31, 2017 at 6:29 PM, Diver Martin <diver.martin@...> wrote:
Hello all,

As I'm doing a motherboard mod, I'm looking to incorporate a bunch of mods into one PCB.  Right now, what I've got going are the following:

* A tuner + SWR Bridge (phase detector maybe?)
* A spot for an RTL-SDR (blogV3) dongle
* AGC Modifications
* Integrating LCD and headphone/mic/BNC/Power/etc jacks into the PCB

Other things I've thought about, space depending:

*Adding in footprints for a chinese AD9850 DDS module for one of the clock signals

I would like to hear the top mods you've done, and what you'd love to see integrated into a motherboard PCB that fits on top of the uBitx.  Battery charger?  Battery adapter? I dunno, bring it on!  If you have a favorite AGC mod, please tell me about it, and make some suggestions as well.  This is not promising to be a cheap kit, and full of SMT, but something I might make available.

Happy new year,

--
Martin Held - AE7EU
http://ae7eu.com/
-------------------------------------------------------------------------------
If there aren't any questions, then what is there to learn?




--
73 Dave WI6R




--
Martin Held - AE7EU
http://ae7eu.com/
-------------------------------------------------------------------------------
If there aren't any questions, then what is there to learn?




--
73 Dave WI6R



--
Martin Held - AE7EU
http://ae7eu.com/
-------------------------------------------------------------------------------
If there aren't any questions, then what is there to learn?

Re: #ubitx IRF510 concerns, different modes #ubitx

Art Howard
 

🙄

On 1 Jan 2018 6:18 pm, "Ghericoan" <boakawizkid@...> wrote:
I have yet to get my ubitx yet, as I am on the preorder list. But I was wondering if there is a way to back the power output down to five watts to save the heat stress on the IRF510s. I am looking to do digital modes like PSK31, WSPR, and possibly playing around with SSTV.

Just concerned on how to go about assembly once the unit is here because I want it to be solid for digital modes. I have already ordered spare MOSFETs, but would rather not get into the habit of replacing them.
--
----------
N5WLF, Greggory (or my nickname, Ghericoan)
General Class, Digital Radio Hobbyist

Re: #ubitx IRF510 concerns, different modes #ubitx

Art Howard
 

General rule of thumb is no more than 25 to 30% of the total output of the rig. He always control the output by the audio level in and if you can monitor it back off until the alc Barely indicates.... Otherwise you will become one of those annoying broad splatter stations

On 1 Jan 2018 6:18 pm, "Ghericoan" <boakawizkid@...> wrote:
I have yet to get my ubitx yet, as I am on the preorder list. But I was wondering if there is a way to back the power output down to five watts to save the heat stress on the IRF510s. I am looking to do digital modes like PSK31, WSPR, and possibly playing around with SSTV.

Just concerned on how to go about assembly once the unit is here because I want it to be solid for digital modes. I have already ordered spare MOSFETs, but would rather not get into the habit of replacing them.
--
----------
N5WLF, Greggory (or my nickname, Ghericoan)
General Class, Digital Radio Hobbyist

Re: #ubitx Power output on 40 / 80 m with high current levels #ubitx

John Backo
 

Alex:

What you are doing is all the right things to find the right combination
to drive the IRF510's. Get a hold of and really read the original article by WA2EBY
for all the things he discovered along the way. The primary thing is taking care of heat.
You seem to have accomplished that. The second is coming up with the proper layout to eliminate
the propensity of the finals to oscillate -- that is probably what you are experiencing.


"I'm working on my uBitx which is completely homybuilt, so not the currently sold PCB version. By building it from scratch you encounter a lot of interesting things and learn a lot about it. Receiving of the rig is very good now but I am struggling with the TX. When aligned for output power of 8 watts, using a sine wave generator and full modulation level, the rig draws about 3,5 amps of current on 40M. At 80M, power output increases to about 12 watts, but current jumps up to around 4 amps. Sometimes my IRF's get killed at that level. There's now way so far I've got it set to say 8 watts with less than 2 amps of current. Things I've done so far are:"


Are you sure you are using SSB? And the amplifier class is really AB? Remember, SSB output is Pk-Pk, while AM is "100% modulation". I would be interested in
seeing if there is any carrier output. This sudden current jump is suspicious of extra oscillation.


"Play around with the HF power gain pot RV1 in combination with more audio drive level"


Don't go above 3v or so on the IRF gate. Maybe even 2.5v. These are very touchy devices and hit a full on current condition with no warning...as you have
already found out.

"Play around with the IRF's bias adjustment. Setting it too high will give a current thermal runaway and a fried IRF within a second. Careful with that...
Output toroids of the IRF balance, changed the windings bifilair, trifilair en more in both directions, so in fact play around with the output impedance with the IRF's see. The trifilair original option seems to be the best bet, but with these high current values. Toroid is a 37-10 with 7 windings trifilair.
Changed the emitter resistances on the 2N2219 to decrease the input power."


IRF MOSFETS are notorious for being extremely variable. You are right that a different batch will give entirely different results. The use of #10 material for the toroid is very good, but I would increase the size to at least a T50, and probably would go to a T68 or even a T100 for high power levels. It doesn't take much to saturate a T37, and then the transformer is an entirely different one. Also, it might be prudent to look for a different form factor for the output transformer, one with a bit more shielding than a toroid. I know, they have a good
reputation, but they are not perfect in a strong RF field.


"I've measured the LPF and it has a cutoff at 7300 KHz so that should be fine.Testing done at 12volts, when at 13,8 volts, the output power and IRF amp values increase dramatically (got over 16 watts of RF) but this often kills one of the IRF's. No way I would keep the IRF's alive on 24 volts.
I don't have the LPF's for the higher bands in place yet, but it seems that at 20m and higher the overall gain of the TX chain decreases. When measured WITHOUT LPF (yes on dummy load, for sure) output power decreases to less than a single watt... This could also be an effect of the bidirectional part of the TX chain where the gain decreases with higher frequencies. For now I'm concentrating on the difference between the behaviour at 40 and 80 meters."


It's unlikely that the bidirectional amps have much to do with radiated power...provided the throughput is adequate. In the case of the BITX, that is roughly 10 dB.
Know also that the IRF510 is not a very good device above 40m. Yes, they can be made to work well, but it takes a good impedance match and heat control to
do so. They also work better at 24v than at 12v. So it is likely that you are seeing VHF oscillation drawing the extra current. That will SEEM like the output to the
antenna is better, but it really is not. Offhand, I would say that you have a layout problem and are using a little too small toroids to handle the load. You might consider
divorcing the final amplifier from the rest of the rig, and working out the rest. Farhan designed the uBITX for a wide range, but rather low power output -- certainly less
than the IRF510 is capable of handling. Any experimental work is good, but it is really in a different league here. I like what you are doing...it is pushing the design into new territory.

john
AD5YE


"Could it be I am just using a wrong brand of IRF's? I have a load coming in from a second supplier to check.
Any other ideas? I have got rechargeable batteries built into my rig and they would last much longer if I could keep the total peak current below 2 amps.

Oh by the way, I've got a very large cooling heat sink and never got it really hot, just 'warm'

Lovely experimental rig!

73, Alex
PA1FOX"

Re: Tell me your favorite uBitx mods

Diver Martin <diver.martin@...>
 

So, this is roughly what I'm thinking for the layout thus far.  Here's what you're seeing thus far:  uBitx is underneath the PCB on .5" standoffs (Supplied with the uBitx kit).  The uBitx itself is 1/4" away from the bottom** of the case.  PCB mounts on top.  Upper left:  Power input, 2x (one for 8V+, other for 12V or PA power, default is to just use the 8V+ line, a relay can change the PA power).   Going counter-clockwise, 5V regulator (I'm going to move that to the lower side of the PCB and use the .1" header from the raduino instead, so that +5V doesn't cross under the RF path), BNC RF output, DSP audio output, Teensy 3.2 control module (Due to higher power MCU w/ dsp capability), Key jack, PTT jack.  There's plenty of room for an AGC mod, the raduino header, and the audio connector.  Right side, the vendor I use for PCB's has options of 15cm x 20cm, so I made use of the extra space on the right to create a 'front panel' pcb.  So Mic and headphones on the front (blue comment layer circles show where the audio jacks would pop out), and one would break off the additional PCB that contains a variable pot for audio gain, encoder (reused from uBitx kit), some pushbuttons (for whatever function you want), and then the HD44780 display shipped with the raduino.  Two headers so that it can be mounted upside down or however you wish. 

**(or top of case) I did this because some people might want the display on the right side of the unit, others on the left, and this can be easily achieved by simply flipping the entire thing upside down in the enclosure.  I'm not sure if the HD44780 can be flipped upside down (I can't see why not), but just in case, footprints are free, would be up to the user to decide where it gets soldered in.  There's a 595 shift register for the display as well.  One thing not shown yet are the connections for right angle .1" headers that would connect the front panel to the main board, easy enough to add later, just haven't done it yet.  

Going back along the top, SWR Bridge components, and the lions share of space for the tuner, and a cutout notch for the uBitx heatsinks.

As you can see, plenty of room on the system for mods.  Just... harder to get front panel space :)

So, full list of features:
AGC(Pending design, feedback is good! - include S-meter)
Tuner
Fast MCU w/ USB back panel access [cat control]
Dual power supplies for TX pwr
DSP audio output
Keying interface
Pushbuttons for the front panel
SWR Bridge
Linear control (Pending, Just a cheap reed relay hooked up to the PTT line basically)

I haven't even thought too much about how much it'd cost to make,  Probably a significant amount :)  I'm putting single-unit costs in my components in the schematic, so that I can take a guess at just the raw BoM cost eventually, but all in due time.



On Mon, Jan 1, 2018 at 5:03 PM, Diver Martin <diver.martin@...> wrote:
So looking at the schematic, it's basically an IF amp (MC1350P, which is obsolete/harder to get, though I have gotten them from Jameco before) with a dual gate mosfet as the attenuation stage.  The rest is just a separate amplifier (Q504-509) and a detector diode (D502) feeding that gate.

What I would ultimately want to do I think is provide one input, and one out on the add-on PCB that I'm doing, and maybe cut at Q30 on the uBitx to get the RF input.  To do the mod, one would cut the trace as indicated, and then solder in some 30ga wire that goes up to the motherboard, which provides the modification.  I'm thinking Q30 is probably the best place to put the AGC, as after the 12Mhz narrow filter, there is no other amplifier, so I'm kinda limited to the 12kHz bandwidth filter to do the AGC I think.



On Mon, Jan 1, 2018 at 2:29 AM, Dave Bottom <ars.kd6az@...> wrote:
Martin,

The Heathkit SB-104/A/HW-104 has an uderly simple AGC system that works so well it was easily the easiest rig to just sit and read the mail.  Round tables with so many different strength signals and it was so pleasant to listen to.  Just a dual insulated gate FET ahead of the IF Gain and there are 8 transistors in the AGC Amplifier, Fast/Slow AGC and S-Meter output.

Schematic attached of SB-104A.

Dave

I actually had a couple of pre-amps for a hi fi project, but used for this kitsrus.com Kit 98, works, but there are simpler circuits.

Dave WI6R

On Mon, Jan 1, 2018 at 1:27 AM, Diver Martin <diver.martin@...> wrote:
Dave,

I agree with many of your points, very specifically, the AGC.  I tried listening in with my uBitx once I got the case wired up, and then promptly had my ears blown off by a nearby static pop or something.  I haven't listened to it since, and won't until I get some form of AGC, hopefully RF-derived... I am very touchy about my hearing, as it's sensitive and you only get one set of years (I wore earplugs all new years this year... hope yours was quieter).  I need to figure out the proper AGC scheme that is best, it should be reasonably easy to do.

Down the line, but a quick note:  Panel space is the biggest premium I'm dealing with. The display alone takes up 3.2" of front panel space.  Either one has to create a mezzanine board to 'stack' buttons/encoders/etc vertically, or you start going to the back panel, the side panels, etc.

1) Already covered above
2) Already in my schematic (I use a BY-1)
3) Already in my schematic
4) S-meter would have to be derived from the AGC, but I see no reason it couldn't be.  I've added in an analog pin.
4b) I have one 'undefined' front panel button.  I'd like to have more if possible... I might add in an extra MCP23S17 to expand my IO's...  (I'm nearly full on the leonardo)
5) Not sure how to implement this one, but if you've got a rough schematic to point me to of your modifications, I can probably include it.  Depends on how the wires would need to go to the PCB below, or if it's something that can just be put inline with the microphone.  Could do a microphone amplifier I suppose...  This is probably the lowest priority out of the things listed for me.
6) It's easy enough to pipe the TX line out to a relay.  I'll consider it based on panel space.
7) Yep, already in the schematic.  For now I'll probably stick to linear / non-phase detector method, but it probably wouldn't be hard to modify for a phase detector.  Just would need to focus on how to do it on the cheap instead of using an AD8307 or 8302 (Which are like $10-25 at digikey).


On Mon, Jan 1, 2018 at 1:15 AM, Dave Bottom <ars.kd6az@...> wrote:
Hi Martin,

 A Second Story is a neat idea that could eliminate wiring with a suitable case that can take advantage of PCB mounted connectors.
Here's my wish list...

Important:
1) Well the top of my list is a really effective AGC.  This is what separates a really great rig from a really good rig.
The basic MicroBITX so reminds me of my SBE SB-33 (1966 - mobile rig) it is the audio derived AGC. 
Back in the day Collins S-Line had great (but complex) AGC that worked(s) great, but..
Nearly every Heathkit SSB rig back in the day had great AGC whether it was a tube HW-12 or a solid state HW-104.
Check out the HW-104 AGC system...

2) Solid CW Keying and for a paddle

3) USB interface to rear panel -  One big reason for this kit is to become proficient working with software.

4) Well if those are done an S-Meter is nice.

Nice to have:
4) Momentary button to toggle between VFO A and VFO B.  If you work split this is really necessary (Yes, I chase DX on QRP)

5) Mic Pre-Amp and Mic Gain -  I added this tonight with the PCB temporarily stuck on the rear panel (all my jacks are on the rear panel out of the way of knobs. 
It helps a little so I don't feel like I have to climb in the Mic, however a Speech Compressor might be more worthwhile.  Being able to use typical Electret Condenser Mics (e.g. ICOM radios) it needs more gain and an adjustment even if a PCB mounted internally accessible set and forget pot.

6) Keying interface for a Linear.  Band data and keying - This baby will drive an RF-KIT 2K+ LDMOS linear to legal limit. (when life is too short for QRP)

When you have nothing better to do:
7) VSWR Bridge with Display for forward/reflected power.  The tuner gets a lot simpler and an external tuner may not need power (manual tuner).

Oh, wait, didn't you do that one already?  LOL

Dave WI6R

On Sun, Dec 31, 2017 at 6:29 PM, Diver Martin <diver.martin@...> wrote:
Hello all,

As I'm doing a motherboard mod, I'm looking to incorporate a bunch of mods into one PCB.  Right now, what I've got going are the following:

* A tuner + SWR Bridge (phase detector maybe?)
* A spot for an RTL-SDR (blogV3) dongle
* AGC Modifications
* Integrating LCD and headphone/mic/BNC/Power/etc jacks into the PCB

Other things I've thought about, space depending:

*Adding in footprints for a chinese AD9850 DDS module for one of the clock signals

I would like to hear the top mods you've done, and what you'd love to see integrated into a motherboard PCB that fits on top of the uBitx.  Battery charger?  Battery adapter? I dunno, bring it on!  If you have a favorite AGC mod, please tell me about it, and make some suggestions as well.  This is not promising to be a cheap kit, and full of SMT, but something I might make available.

Happy new year,

--
Martin Held - AE7EU
http://ae7eu.com/
-------------------------------------------------------------------------------
If there aren't any questions, then what is there to learn?




--
73 Dave WI6R




--
Martin Held - AE7EU
http://ae7eu.com/
-------------------------------------------------------------------------------
If there aren't any questions, then what is there to learn?




--
73 Dave WI6R



--
Martin Held - AE7EU
http://ae7eu.com/
-------------------------------------------------------------------------------
If there aren't any questions, then what is there to learn?




--
Martin Held - AE7EU
http://ae7eu.com/
-------------------------------------------------------------------------------
If there aren't any questions, then what is there to learn?