Date   
Re: Replacing the PA section on Bitx 40

M Garza <mgarza896@...>
 

Why replace everything?  You can probably put it in place of the 510 (making sure it is pinned correctly, of course).  
I am waiting on a pair, myself, that I will be stuffing into the ubitx.   I want to even out the power output.  I will also try a resistor/capacitor in parallel, in series with the gate, to try and even out the frequency response.  I am thinking 4.7 ohm & 4700pf.  I will also try 6.8 ohm & 4700pf.  Depends on how flat I can get the output.

Marco - KG5PRT 

On Jan 31, 2018 10:12 PM, "James Lawrie" <lawriejk@...> wrote:
Hello,

My shipment of replacement RF Mosfets have arrived and I want to replace the on board PASection with one based on the RD16HHF1. It will be a separate small PCB based on the reference design shown in the data sheet. I need help from the professionals here as to where to attach the new PA board.

I know it would be somewhere after the 2N2219A driver, and I want to remove all bypassed SMTs and or other parts from the Bitx board in that area. If you have a pretty good idea could you please let me know, and possibly a drawing if you could. This should keep me busy and off the forum for a while.

Thanks,


James Lawrie

Re: Second batch of uBITX shipping? #ubitx

Art Howard
 

Getting closer ordered mine the 18th

On 31 Jan 2018 9:57 am, "dj0hf" <dj0hf@...> wrote:
Ordered on the 16th Dec and posted by HFSigs 30th Jan.
I now have a tracking number so it's looking good. Can't wait to start playing with it.

73
Ian
DJ0HF/G3ULO




Re: uBITX AM BCI Filter #ubitx

John <passionfruit88@...>
 

Hello Nick,

I am very interested in knowing what results you get. 

My main objectives in not placing it in the Tx path are to reduce the toroid size and to avoid introducing extra mis-match as I have built the unit in a manpack configuration. So I want to glue the toroids down when everything is working.

As for the QSO, I would like to, but until I replace Arduino nano I have very strong tones in and outside the passband.

So hopefully I will receive the replacement Arduino soon.

All the best,

73, John (VK2ETA)

Re: [uBITX] Key line resistor: OK to mount on Raduino board?

Clark Martin
 

That’s what I did, I put an 0805 SMD resistor in between the pins of the digital connector. It fits quite nicely. And it works fine

Clark Martin
KK6ISP

On Jan 31, 2018, at 6:11 PM, K5DH <k5dh@...> wrote:

There is a 4700 Ohm pullup resistor that must be installed between +5 V and the key line. The wiring instructions show it being installed at the key jack. Is it OK to install it on the Raduino board, on the solder side of the Digital connector? Or is soldering to that board too risky?

LTSpice simulation of uBitx Power Amp

Jerry Gaffke
 

I've uploaded an LTSpice simulation of the uBitx Power Amplifier from Q90 on out through the IRF510's
but not including any of the transmit low pass filters, can be found here:
    https://groups.io/g/BITX20/files/KE7ER/ubitx_pa.asc
A pdf of the LTSpice schematic is here:
    https://groups.io/g/BITX20/files/KE7ER/ubitx_pa.pdf

I ran several simulations, all with a 0.05 volt pk-to-pk sine wave driven into C80 at the base of Q90.
Anything much higher and there was some definite gain compression going on.

With the IRF510 gates clipped out of the circuit, I saw 7.7v p-p of drive for each gate at 30mhz, 10.0v p-p at 7mhz.
Note that these signals were still loaded by the 47ohm resistors at R97 and R98

With the gates restored and the IRF510's powered from 12v, the gates had 3.0v p-p at 30mhz, 8.0v p-p at 7mhz.
Simulated power out (computed from the unfiltered p-p voltage into 50 ohms) was 5W at 7mhz and 0.9W at 30mhz. 
  
Will be interesting to see what this does if the gates are driven harder.
Also interesting to try a simulation of the WA2EBY amp using the same IRF510 models.

Jerry, KE7ER

Re: BITX40 V2.03 UPGRADE

JH1OJY
 


Thanks for nice info.
I had replaced 10k to 4.7k before this question.
I tried to replace 4.7k to 2.4k or 1.5k.  finally 1.5k but output power doesn't go up, still 3w.
This resister is available for CW but not LSB I think. 
Anyway I will search how to make output power up.

Hiro  JH1OJY

Re: BITX40 V2.03 UPGRADE

Allard PE1NWL
 

Hi Hiro san,

Each time after you replaced the resistor to a lower value, did you also
perform recalibration?
Changing the resistor value may have some effect on the optimum
calibration point for maximum power output in CW.

Do you have correct power output in other modes (LSB, USB, CWU) or only in
CWL?
Is power output correct in VFO setting LOW or HIGH?
What VFO calibration value (ppm), and what BFO frequencies did you find
during calibration procedures for each mode?

73 Allard PE1NWL

On Thu, February 1, 2018 08:40, JH1OJY wrote:
Thanks for nice info.
I had replaced 10k to 4.7k before this question.
I tried to replace 4.7k to 2.4k or 1.5k.  finally 1.5k but output power
doesn't go up, still 3w.
This resister is available for CW but not LSB I think. 
Anyway I will search how to make output power up.

Hiro  JH1OJY

Re: uBITX Firmware (CEC) 0.30 released (Test version). #ubitx

Kari Syrjänen
 

Ian's firmwares working great! I have been using then since version 0.25

Now running 0.33 and working 7MHz FT8-mode. Over 350 QSO.s in my logbook

TNX!

Kari OH5YW

Re: Replacing the PA section on Bitx 40

 

Here is how I made the socket and mounted the RDD16

Note the RDD is reversed and  then the gate is actually soldered to the IRF gate line which goes behind the FET.
Now I can use either of them..

You will need to think of a heat sink plate that fits this way!

Emacs!


At 01/02/2018, you wrote:
Why replace everything?  You can probably put it in place of the 510 (making sure it is pinned correctly, of course). Â
I am waiting on a pair, myself, that I will be stuffing into the ubitx.   I want to even out the power output.  I will also try a resistor/capacitor in parallel, in series with the gate, to try and even out the frequency response.  I am thinking 4.7 ohm & 4700pf.  I will also try 6.8 ohm & 4700pf.  Depends on how flat I can get the output.

Marco - KG5PRTÂ

On Jan 31, 2018 10:12 PM, "James Lawrie" <lawriejk@...> wrote:
Hello,
My shipment of replacement RF Mosfets have arrived and I want to replace the on board PASection with one based on the RD16HHF1. It will be a separate small PCB based on the reference design shown in the data sheet. I need help from the professionals here as to where to attach the new PA board.
I know it would be somewhere after the 2N2219A driver, and I want to remove all bypassed SMTs and or other parts from the Bitx board in that area. If you have a pretty good idea could you please let me know, and possibly a drawing if you could. This should keep me busy and off the forum for a while.

Re: Dynamic mic on ubitx

Dave Bottom <ars.kd6az@...>
 

Dennis,

Modifications to use a Dynamic Mic.
Referring to the uBITX Schematic.  The Gain of the Mic PreAmp is controlled by R63 in the Emitter of Q6 to C62/R64.  It basically decouples the audio bypass of R64 by C62 to limit gain for the high output Electret Mics.  Replacing R63 with a Zero Ohm resistor and putting a 10K at the Mic input should allow a Dynamic Mic to work now with a Mic Gain Control.  Also R60 that supplies Mic BIAS to the Electret-Condenser Mic needs to be removed.  If there is not enough Gain still, you might have to reduce the value of R64 to maybe 470 Ohms or so.  If you cannot look at your transmitted signal on a scope at least listen to your audio on another receiver to verify you are not causing distortion.

More Gain for the Electret Mic
To simply get more gain with an Electret Mic you might try dropping another 47 Ohm chip resistor on top of the existing R63 by soldering another chip resistor one end at a time.

Dave WI6R

On Wed, Jan 31, 2018 at 6:13 AM, Dennis Yancey <bigbluedry@...> wrote:
has anyone used a dynamic mic on the ubitx? If you have, please givedetails such aspiring, did you use any preamp, etc. also what were the results as reported by others?

thanks.




--
73 Dave WI6R

Re: Dynamic mic on ubitx

Marc Jones
 

Just put a DC Blocking cap in series , I use a old CB hand mic, Works fine .

On Wed, 31 Jan 2018 at 14:13, Dennis Yancey
<bigbluedry@...> wrote:
has anyone used a dynamic mic on the ubitx? If you have, please givedetails such aspiring, did you use any preamp, etc. also what were the results as reported by others?

thanks.

uBITX schema relay K1 #ubitx

pe0fko
 

Hello group,

After looking at the very nice schema of the uBITX (http://www.hfsignals.com/wp-content/uploads/2017/12/ubitxv3.pdf) i have a question about the K1 relay.
The K1 relay is used for the RX and TX power switching and also for connecting the antenna in RX to the LP filter.

On RX (and TX) the LP filter is also a connection to the TX power amp by C80, that will give a (very) small load on the antenna signal at RX and a mixer (Q90 diode BE) for strong received signals?
It can be changed by by switching the pins 12 and 14 of K1 and connection pin 16 of K1 to C80 (remove that one from the LP filter)?

I do not own a board (yet), so i cannot test it.
Maybe there are very well reasons for using it as it is, I did not read the total history.

73, Fred
pe0fko

Re: uBITX Firmware (CEC) 0.30 released (Test version). #ubitx

Andrew Farkas <afarkas@...>
 

Very nice. I wish I could figure out FT-8. I can't get anyone to comeback on my regular rig. These apps are very intricicate. Too bad there isnt some kind of standard for making radio software work.

Andy

VA3AAF

On Feb 1, 2018 3:19 AM, Kari Syrjänen <beaconhunter@...> wrote:
Ian's firmwares working great! I have been using then since version 0.25

Now running 0.33 and working 7MHz FT8-mode. Over 350 QSO.s in my logbook

TNX!

Kari OH5YW

Re: [SPAM] Re: [BITX20] Replacing the PA section on Bitx 40

K9HZ <bill@...>
 

I really like that!   If you fold the RD16 over you could use a heat sink out the back…

 

 

Dr. William J. Schmidt - K9HZ J68HZ 8P6HK ZF2HZ PJ4/K9HZ VP5/K9HZ PJ2/K9HZ

 

Owner - Operator

Big Signal Ranch – K9ZC

Staunton, Illinois

 

Owner – Operator

Villa Grand Piton – J68HZ

Soufriere, St. Lucia W.I.

Rent it: www.VillaGrandPiton.com

Like us on Facebook! facebook icon

 

 

email:  bill@...

 

From: BITX20@groups.io [mailto:BITX20@groups.io] On Behalf Of Raj vu2zap
Sent: Thursday, February 01, 2018 4:24 AM
To: BITX20@groups.io
Subject: [SPAM] Re: [BITX20] Replacing the PA section on Bitx 40

 

Here is how I made the socket and mounted the RDD16

Note the RDD is reversed and  then the gate is actually soldered to the IRF gate line which goes behind the FET.
Now I can use either of them..

You will need to think of a heat sink plate that fits this way!

Emacs!

At 01/02/2018, you wrote:

Why replace everything?  You can probably put it in place of the 510 (making sure it is pinned correctly, of course). Â
I am waiting on a pair, myself, that I will be stuffing into the ubitx.   I want to even out the power output.  I will also try a resistor/capacitor in parallel, in series with the gate, to try and even out the frequency response.  I am thinking 4.7 ohm & 4700pf.  I will also try 6.8 ohm & 4700pf.  Depends on how flat I can get the output.

Marco - KG5PRTÂ

On Jan 31, 2018 10:12 PM, "James Lawrie" <lawriejk@...> wrote:

Hello,

My shipment of replacement RF Mosfets have arrived and I want to replace the on board PASection with one based on the RD16HHF1. It will be a separate small PCB based on the reference design shown in the data sheet. I need help from the professionals here as to where to attach the new PA board.

I know it would be somewhere after the 2N2219A driver, and I want to remove all bypassed SMTs and or other parts from the Bitx board in that area. If you have a pretty good idea could you please let me know, and possibly a drawing if you could. This should keep me busy and off the forum for a while.

Re: [SPAM] Re: [BITX20] Replacing the PA section on Bitx 40

K9HZ <bill@...>
 

Also… have you had it on the air like that yet?

 

 

Dr. William J. Schmidt - K9HZ J68HZ 8P6HK ZF2HZ PJ4/K9HZ VP5/K9HZ PJ2/K9HZ

 

Owner - Operator

Big Signal Ranch – K9ZC

Staunton, Illinois

 

Owner – Operator

Villa Grand Piton – J68HZ

Soufriere, St. Lucia W.I.

Rent it: www.VillaGrandPiton.com

Like us on Facebook! facebook icon

 

 

email:  bill@...

 

From: BITX20@groups.io [mailto:BITX20@groups.io] On Behalf Of Raj vu2zap
Sent: Thursday, February 01, 2018 4:24 AM
To: BITX20@groups.io
Subject: [SPAM] Re: [BITX20] Replacing the PA section on Bitx 40

 

Here is how I made the socket and mounted the RDD16

Note the RDD is reversed and  then the gate is actually soldered to the IRF gate line which goes behind the FET.
Now I can use either of them..

You will need to think of a heat sink plate that fits this way!

Emacs!

At 01/02/2018, you wrote:

Why replace everything?  You can probably put it in place of the 510 (making sure it is pinned correctly, of course). Â
I am waiting on a pair, myself, that I will be stuffing into the ubitx.   I want to even out the power output.  I will also try a resistor/capacitor in parallel, in series with the gate, to try and even out the frequency response.  I am thinking 4.7 ohm & 4700pf.  I will also try 6.8 ohm & 4700pf.  Depends on how flat I can get the output.

Marco - KG5PRTÂ

On Jan 31, 2018 10:12 PM, "James Lawrie" <lawriejk@...> wrote:

Hello,

My shipment of replacement RF Mosfets have arrived and I want to replace the on board PASection with one based on the RD16HHF1. It will be a separate small PCB based on the reference design shown in the data sheet. I need help from the professionals here as to where to attach the new PA board.

I know it would be somewhere after the 2N2219A driver, and I want to remove all bypassed SMTs and or other parts from the Bitx board in that area. If you have a pretty good idea could you please let me know, and possibly a drawing if you could. This should keep me busy and off the forum for a while.

Slack chat client

Richard E Neese
 

Re: Replacing the PA section on Bitx 40

James Lawrie
 

My thought process is a separate board would allow more mounting options for a heat sink, and cleaner layout after on the Bitx 40. I hate to admit it but I’m not an engineer and even my basic math skills for electronics formula is severely restricted due to the “happy pills” I take for my service connected TBI and PTSD.

As a kid when I was trying to get into electronics and Ham I had a Elmer who helped, but now 41 years later I know no one else in my area who could/would help.I can follow schematics, and do basic - mid level troubleshooting, speaking of worse things I used to be very proficient in basic, pascal and early OOP programming, now thanks to my medical issues they are gone. I look a c and c++ and think it must be from Mars.

Probably TMI about myself but this is why I ask for help and like a clean board.

James Lawrie

Re: [SPAM] [BITX20] LTSpice simulation of uBitx Power Amp

K9HZ <bill@...>
 

Jerry… thanks for doing this.  I had intended to do this same thing but so many things kept getting in the way.  Since you uploaded the .asc I’ll try some of my favorite PA transistors in place of the 510s when I get back from vacation and see how they look.  The 3904s should be good above 50 mhz. also I suspect the stages are coupled a bit too tightly at higher frequency where something smaller would be more appropriate.  Anyway, nice work.

 

This does point out a few “oh yeah” things though.  The 510 miller cap loading at the higher frequencies is very high.  I guess you see that in the smith chart of the spec sheet too so no surprise.  Also, I think we see a lot of variation in the 510 parts…as some people report them working well at 20+ MHz and some not so much.

 

Yes agree.  I’d love to see a sim of the WA2EBY amp.  Dying to know the efficiency at 30 MHz.

 

 

Dr. William J. Schmidt - K9HZ J68HZ 8P6HK ZF2HZ PJ4/K9HZ VP5/K9HZ PJ2/K9HZ

 

Owner - Operator

Big Signal Ranch – K9ZC

Staunton, Illinois

 

Owner – Operator

Villa Grand Piton – J68HZ

Soufriere, St. Lucia W.I.

Rent it: www.VillaGrandPiton.com

Like us on Facebook! facebook icon

 

 

email:  bill@...

 

From: BITX20@groups.io [mailto:BITX20@groups.io] On Behalf Of Jerry Gaffke via Groups.Io
Sent: Thursday, February 01, 2018 3:24 AM
To: BITX20@groups.io
Subject: [SPAM] [BITX20] LTSpice simulation of uBitx Power Amp

 

I've uploaded an LTSpice simulation of the uBitx Power Amplifier from Q90 on out through the IRF510's
but not including any of the transmit low pass filters, can be found here:
    https://groups.io/g/BITX20/files/KE7ER/ubitx_pa.asc
A pdf of the LTSpice schematic is here:
    https://groups.io/g/BITX20/files/KE7ER/ubitx_pa.pdf

I ran several simulations, all with a 0.05 volt pk-to-pk sine wave driven into C80 at the base of Q90.
Anything much higher and there was some definite gain compression going on.

With the IRF510 gates clipped out of the circuit, I saw 7.7v p-p of drive for each gate at 30mhz, 10.0v p-p at 7mhz.
Note that these signals were still loaded by the 47ohm resistors at R97 and R98

With the gates restored and the IRF510's powered from 12v, the gates had 3.0v p-p at 30mhz, 8.0v p-p at 7mhz.
Simulated power out (computed from the unfiltered p-p voltage into 50 ohms) was 5W at 7mhz and 0.9W at 30mhz. 
  
Will be interesting to see what this does if the gates are driven harder.
Also interesting to try a simulation of the WA2EBY amp using the same IRF510 models.

Jerry, KE7ER

Re: Nextion Display

Michael Monteith
 

Fred,
 Have you posted your work somewhere?  I bought a Nextion display over a year ago.  At the time the software was pretty messy.  I haven't touched it since.  But I would like to again.  Now I know who to bug if I have problems trying it again. lol  It would be great to have a professional looking display for the Bitx and uBitx systems.   I've got both to build at the moment.  Waiting on parts for one and pretty much spare time to work on the other.

73, Michael
KM4OLT

Re: Software support Request for Full QSK BITX40

Gary O'Neil
 

Thanks for doing the work generating the LTSpice file for the BITX40 PA. Saved me time and effort. I integrated my RF switch as it stands currently, and attaching it so you and others who might have the skillset to scrutinize and critique it. You're way ahead of me on the other emails, and it may be a fair amount of time before I get to them. I'm still peeling the onion on this switch at the moment, and don't want to divert my focus.

Tale a look at S21 in both transmit and receive. It looks great in Transmit mode, but receive insertion loss looks a wee bit high but not a show stopper. I also haven't taken a look at the before configuration yet, so it's not clear the switch is what's behind the insertion loss. By itself, the switch simulates (and measures) 0.2 dB insertion loss in receive.

Thanks again for doing the leg work on this... The integration was fast and easy. :-)

72/73

Gary, N3GO