Date   

Re: uBitx Prototype (PCB)

Jerry Gaffke
 

Though I now see Ion's mention that PCBWAY is pretty quick too:  

> or 40 PCBs for $35 and you have them in about 10 days.


On Sat, Apr 8, 2017 at 03:44 pm, Jerry Gaffke wrote:

If only doing a few square inches on some prototype boards, it doesn't make sense to wait a month.  

 


Re: uBitx Prototype (PCB)

Jerry Gaffke
 

I may use PCBWAY at some point.  Good prices, and they claim 4 and 4 mil design rules.  

I use OSHpark when it makes sense, as they manufacture here in the US for a nice quick turn, produce beautiful boards with an ENIG finish, and have a very nice web interface for submitting gerbers.  Many of the PJRC boards go through OSHpark.  If only doing a few square inches on some prototype boards, it doesn't make sense to wait a month.  


On Sat, Apr 8, 2017 at 03:12 pm, Ion Petroianu wrote:

I use PCBWAY.

 


Re: VFO/BFO selecting outputs

Jerry Gaffke
 

We are using coax to shield the critical signals, not so much as transmission line.  The coax shield on both ends should be tied to a suitable ground.  If used on the volume pot (I have no idea if that will help in your particular situation), you probably need two pieces of coax because there are two critical signals.

According to this webpage, RG-174 is 2.55mm in diameter, RG-178 is is the smallest listed at 1.8mm:  https://en.wikipedia.org/wiki/Coaxial_cable    The RG series spec was last updated in 1962.  I have some nice flexible 1.5mm coax on hand, no identifying marks and no idea what it might be called.

If you don't want to mess with coax, twisted pairs are a good second best.  Just twisting the wire provided by hfsigs will help, but better to use smaller diameter wire as that allows the wires to be closer together.  Twist a ground wire with the critical signal wire, perhaps one or two turns per inch.  In the case of the volume pot, could just twist all three wires together since we don't care if the two signal wires interact.


On Sat, Apr 8, 2017 at 12:45 pm, Jerry Gaffke wrote:

 The impedance (50 or 75 ohms) should not matter much

 


Re: uBitx Prototype (PCB)

Ion Petroianu, VA3NOI
 

I use PCBWAY.

I did a quick quote for a board the size of BitX and it works at $62/5 boards sipped to Canada by DHL.

I use them for all my boards needs as they have a regular price of $10/10 boards no bigger than 100X100 mm plus shipping.

I am a cheap bastard so I choose shipping by HK mail and it brings the cost to $23/set.

Now the boards can have multiple layouts on them.

For my PCB design of the BidiAmp I can fit 4 of them on each board so 40 BidiAmps PCBs for $23 if you wait 3 weeks or 40 PCBs for $35 and you have them in about 10 days.

The quality is very good and they are running right now a promotion, so 10 boards for only $5, or $18 shipped regular post, or $30 shipped DHL.
--
Ion

VA3NOI


Re: VFO/BFO selecting outputs

Ron VE8RT <ve8rt@...>
 

On the header connectors the contacts were extracted and re-used
with the RG178. As I had spare contacts on hand new ones were used if
required. The antenna and LO wires were both replaced with RG178. The
photo may give you an idea of how small it is.

Ron VE8RT

On Sat, 08 Apr 2017 13:02:31 -0700
"Jonathan Peakall" <jpeakall@...> wrote:

No, it's the raduino board. I probably wasn't very clear. All of the
clock outputs do go to the PCB holes for the SIP header. But only the
first 5 pins of the header actually have pins in them, the rest are
open. I'll have to find which is which (0,1,2) but one clock output is
in the middle of the 5 pins that are soldered into the PCB. The others
go to blank holes which I could easily solder into with the RG-174. Hope
that makes it clear as mud!

BTW, what coax is smaller and more flexible that RG-174? Got a number?

Thanks for the help!

Jonathan
--
Ron VE8RT <ve8rt@...>


Re: ubitx - stop press

selfy.dtp@...
 

Thank you Ashhar,

My 'observations' show that proper termination of the QER filter (and matching the crystals!) provides lower ripple in the pass-band together with lower losses. It really depends on what kind of crystals one is using. Mine required 150pF capacitors to ground to achieve 2.7kHz -3db pass-band and -4 dB loss @ 50 ohms at both ends.

My experience is limited only to Minima crystal filter. I modified the Rx part of the bidirectional amplifier to the original Wes/Kopski circuit with a gain of +24dB (theoretical). I am still fighting with the KISS mixer, but I guess I go into too much off topic here.

Thanks once again and 73!


On Sat, Apr 8, 2017 at 6:32 PM, Ashhar Farhan <farhanbox@...> wrote:
i have measurer the input impedance of these stages to be appox 50 ohms when terminated in the 220 resistor in the output. i made these measurements with a homemade return loss bridge and the sweeperino. 
the original wes/kopski amps uses separate resistors for bias and feeback, i used just one. if you want to experiment with different feedback resistors while keeping the bias the same, you could use the original block.
the noise figure should be 14 db. i say that because i havent measured it. i do not have calibrated noise source. this figure is based on the accumulated (measured) losses of the lpf, first mixer and the first if amps figure of 6 db.
connecting the antenna brings up the noise on all bands at my qth. i must, though admit that i havent had any contacts in 28 mhz at all.
- f

On 8 Apr 2017 7:52 p.m., <selfy.dtp@...> wrote:
Farhan,

Let me first thank you for the projects and experience you share with us. I am interested to find out how uBITX behaves in terms of selectivity and sensitivity?

I also support the idea, that if you want to cover all HF band a set of (at least) four LPF for the PA is a must.

Additionally, looking at the uBITX schematic, I couldn't help but notice the bidirectional amps slightly differ form the original idea of W7ZOI and K3NHI. You used different biasing approach, but it appears the input impedance is not 50 ohms. My LTSpice simulations show 90 ohms at 10MHz and 50 ohms at 45MHz. And the "gain" transistor is biased at 15mA. Would you, please, share with us what your idea was for doing these mods.

73 de LZ1NEF




Re: VFO/BFO selecting outputs

Ron VE8RT <ve8rt@...>
 

I'm using Harbour Industries M17/93-RG178 purchased from
www.therfc.com There are likely other sources for RG178

Ron VE8RT

On Sat, 08 Apr 2017 13:02:31 -0700
"Jonathan Peakall" <jpeakall@...> wrote:

No, it's the raduino board. I probably wasn't very clear. All of the
clock outputs do go to the PCB holes for the SIP header. But only the
first 5 pins of the header actually have pins in them, the rest are
open. I'll have to find which is which (0,1,2) but one clock output is
in the middle of the 5 pins that are soldered into the PCB. The others
go to blank holes which I could easily solder into with the RG-174. Hope
that makes it clear as mud!

BTW, what coax is smaller and more flexible that RG-174? Got a number?

Thanks for the help!

Jonathan





On 4/8/2017 12:45 PM, Jerry Gaffke via Groups.Io wrote:

All three Si5351 outputs are routed from the Si5351 to the Raduino's
P3 connector through 0.1uF DC blocking caps. You need those DC
blocking caps. Perhaps you are using a different Si5351 breakout
board? I believe the Bitx40 currently uses CLK2 for the VFO, leaving
CLK0 and CLK1 available. I suggest you use CLK0 for the BFO. I've
seen reports that there is more crosstalk between channels when using
CLK1.

You should be able to find skinnier and more flexible coax out there
than RG-174 if that's an issue. The impedance (50 or 75 ohms) should
not matter much at these frequencies for these frequencies (below 50
mhz) on coax pieces of just a foot or so in length. It's possible
that the volume control and microphone input could benefit from coax also.


On Sat, Apr 8, 2017 at 12:35 pm, Jonathan Peakall wrote:

Getting ready to convert over to using the si5351 for the BFO. I'd
like to use rg-174 for both the VFO and BFO lines. The Si5351 has
three outputs. The first is already routed on the PCB to the SIP
header making it inconvienent to solder coax to it. Is there any
reason that I can't use the two other Si5351 outputs that aren't
used? That would be easy to solder to.


--
Ron VE8RT <ve8rt@...>


Re: VFO/BFO selecting outputs

Jonathan Peakall
 

No, it's the raduino board. I probably wasn't very clear. All of the clock outputs do go to the PCB holes for the SIP header. But only the first 5 pins of the header actually have pins in them, the rest are open.  I'll have to find which is which (0,1,2) but one clock output is in the middle of the 5 pins that are soldered into the PCB. The others go to blank holes which I could easily solder into with the RG-174. Hope that makes it clear as mud!

BTW, what coax is smaller and more flexible that RG-174? Got a number?

Thanks for the help!

Jonathan





On 4/8/2017 12:45 PM, Jerry Gaffke via Groups.Io wrote:

All three Si5351 outputs are routed from the Si5351 to the Raduino's P3 connector through 0.1uF DC blocking caps.  You need those DC blocking caps.  Perhaps you are using a different Si5351 breakout board?  I believe the Bitx40 currently uses CLK2 for the VFO, leaving CLK0 and CLK1 available.  I suggest you use CLK0 for the BFO.  I've seen reports that there is more crosstalk between channels when using CLK1.  

You should be able to find skinnier and more flexible coax out there than RG-174 if that's an issue.  The impedance (50 or 75 ohms) should not matter much at these frequencies for these frequencies (below 50 mhz) on coax pieces of just a foot or so in length.  It's possible that the volume control and microphone input could benefit from coax also.


On Sat, Apr 8, 2017 at 12:35 pm, Jonathan Peakall wrote:

Getting ready to convert over to using the si5351 for the BFO. I'd like to use rg-174 for both the VFO and BFO lines. The Si5351 has three outputs. The first is already routed on the PCB to the SIP header making it inconvienent to solder coax to it. Is there any reason that I can't use the two other Si5351 outputs that aren't used? That would be easy to solder to.

 



Re: The Users User Manual

Jerry Gaffke
 

John,

Good first stab at this, thanks for doing this.

Regarding this statement:  

>  Calibration will get you transmitting on the same frequency as the signal you are hearing.

Calibration just makes the display show the correct frequency, if left uncalibrated it may be off by a few hundred Hz.  If you adjust the frequency till you clearly receive some other ham's SSB signal, your transmitted signal will be exactly on that same frequency.  Even if the rig has not been calibrated.


On Sat, Apr 8, 2017 at 12:25 pm, John Smith wrote:

Calibration will get you transmitting on the same frequency as the signal you are hearing.

 


Re: VFO/BFO selecting outputs

Jerry Gaffke
 

All three Si5351 outputs are routed from the Si5351 to the Raduino's P3 connector through 0.1uF DC blocking caps.  You need those DC blocking caps.  Perhaps you are using a different Si5351 breakout board?  I believe the Bitx40 currently uses CLK2 for the VFO, leaving CLK0 and CLK1 available.  I suggest you use CLK0 for the BFO.  I've seen reports that there is more crosstalk between channels when using CLK1.  

You should be able to find skinnier and more flexible coax out there than RG-174 if that's an issue.  The impedance (50 or 75 ohms) should not matter much at these frequencies for these frequencies (below 50 mhz) on coax pieces of just a foot or so in length.  It's possible that the volume control and microphone input could benefit from coax also.


On Sat, Apr 8, 2017 at 12:35 pm, Jonathan Peakall wrote:

Getting ready to convert over to using the si5351 for the BFO. I'd like to use rg-174 for both the VFO and BFO lines. The Si5351 has three outputs. The first is already routed on the PCB to the SIP header making it inconvienent to solder coax to it. Is there any reason that I can't use the two other Si5351 outputs that aren't used? That would be easy to solder to.

 


VFO/BFO selecting outputs

Jonathan Peakall
 

HI All,

Getting ready to convert over to using the si5351 for the BFO. I'd like to use rg-174 for both the VFO and BFO lines. The Si5351 has three outputs. The first is already routed on the PCB to the SIP header making it inconvienent to solder coax to it. Is there any reason that I can't use the two other Si5351 outputs that aren't used? That would be easy to solder to. And if so do I change the sketch like:

#define VFO_A 0
#define VFO_B 1

to

#define VFO_A 1
#define VFO_B 2

I've never done Arduino before, but that looks like it to me. Anything else?

Jonathan - KK6RPX


The Users User Manual

John Smith
 

The wire up instructions are pretty good down to a certain point. 

When you get to the section of Alignment of the BITX40. Notice #5 is blank. Why it is blank is unknown. But this is where you can adjust R136 (a flat silver trimmer you can adjust with a small blade screwdriver, on the same edge of the board at the PA) to obtain the slightly over 1 amp mentioned in step #6. 

Calibrating the Raduino frequency offset will also require you to download a fixed copy of someone's sketch version found in the files section on the left side if this page. Like mine for example. which has other fixes and tweaks to how it tunes and displays the frequency. Here is a link- https://groups.io/g/BITX20/files/John_s_Raduino_code_fixed2.ino Some others may have posted one too with what was important for them to share. Just try to get the one you like from a reliable source. Getting all the libraries in your Arduino IDE for these sketches is likely to give you some compiling errors at first. After that the IDE gives you clues as what to fix. This part could be a whole other section for the newcomer without a working code at the beginning of the build, or when it get's erased like mine did from a shorted wire.

Calibration will get you transmitting on the same frequency as the signal you are hearing. A higher or lower pitched voice means you are not on the same freq. Once you put it in calibration mode you will need to tune around for that signal you were listening to, and adjust the freq until it sounds normal to you. Then turn off the switch, or disconnect the RED wire. Wait for it to indicate SAVED. Then you can reboot it. You can do it again if other frequencies have signals that don't sound like the one you were using to set your calibration. Sometimes others are deliberately not on a 5khz spacing and will sound strange to you if you are expecting them to be on a set freq.

Some folks have had trouble with wiring tuning or volume pots.

The flat diagram near the top of the wire up page-http://www.hfsigs.com/bitx40v3_wireup.html -shows the parts like they are laid out on the table with the shafts pointing up.

With photos like this one-http://www.hfsigs.com/raduino_tuning_pot.jpg - Just hold the pot with the pins facing you, and the shaft facing down. Then follow with Green, Violet, Yellow.And the ceramic cap connects to the same pin as Violet, and Yellow. The two on the right.

Stopping at the 8 pin connector when just only three wires are used slipped past me. I missed the part going to the 5 pin connector, and kept going with wires from the 8 pin set. Fortunately I double checked my work before giving it juice. 

These are my first thoughts on getting people past the first hiccups that seem common in the beginning. As well as that missing #5 instruction that keeps people wondering why they are not getting the expected readings on their meters. 

Are there any more important things to add, or correct?

Next time I'll post about the stereo audio jacks wire up.


Re: ubitx - stop press

Jerry Gaffke
 

Off topic, just feeling my way through on this specan stuff.  

The AD8310 is spec'd for a maximum input of +/- 2 volts pk-to-pk, or 4 dBV.  So I'd want at least enough gain after my level 7 mixer to be able to drive the AD8310 to that maximum without having appreciable distortion crop up in the mixer.   That should give the instrument the 95dB dynamic range available from the AD8310.

More gain than that is a good thing, allows us to see lower level signals.  Can always use a step attenuator when looking at large signals.  But at some point the front end is generating enough noise that more gain does not buy anything.

Correct me if I've missed something here.



On Sat, Apr 8, 2017 at 06:50 am, Jerry Gaffke wrote:

really have to build a basic spectrum analyzer.   Perhaps just an Si5351 breakout board, a 50mhz lowpass filter, a level 7 mixer, a PX1002 86.85mhz SAW filter, an MMIC gain stage, and an AD8310 into a Nano's ADC.    Or do I need more gain stages for this to be useful?

 


Re: Adding speech compression.

Jerry Gaffke
 

Should work as expected if you increase the gain of the microphone amp:  https://groups.io/g/BITX20/message/24437

Assume you raise the signal coming out of the microphone amp by 3dB (double the power).  Assume the diodes conduct pretty severely on any voice peaks, and reduce them by a factor of 2, so your peak power into the crystal filter is back down to where you started out.  But the quieter parts of your voice (for those of us that have any) have not been clipped back, and remain at twice the power.  


On Sat, Apr 8, 2017 at 11:14 am, John Smith wrote:

I showed the schematic from Allard to someone, and he said the two diodes are shorting the AC signal to ground, and would result in a lower quieter signal.

 


Re: ubitx - stop press

G1KQH
 

This was always tricky when building multiband homebrew, that's why many went for single band design, building up a bank of boxes one for each band.

Good luck Ashhar.

73 Steve


G1KQH




Re: Adding speech compression.

John Smith
 

I listened to it. Everything I have read and heard, all are the same. It's great to help being heard through QRN or QRM, There are different ways to do it like audio clipping or RF clipping. And lots of caution about using it poorly, or it amplifies all room noise, or so and so forth.

Bottom line- If you got it, try it. If it helps, great. Otherwise, leave it alone.

I showed the schematic from Allard to someone, and he said the two diodes are shorting the AC signal to ground, and would result in a lower quieter signal.

It's still a mystery to me how that would work. I am going to try out that circuit I posted a link to when I get the transistor it uses. Or maybe sub the part. 


Re: ubitx - stop press

Craig Wadsworth <cwadsworth@...>
 

Ash,

I'm still gathering parts for my first build of your uBitX (and your Specan!) and have not even started to draw the boards, so adding filters and tweaking the code for switching bands appears trivial.

" . . . replaced the two filter harmonic filters with four filters . . . it works."

You saved us some grief and perhaps FCC fines by telling us about your tests. We grumble, we complain, and we argue, but I believe most of us are having fun and accidentally learning some good stuff along the way.

Other than encouraging fellow hams to purchase from HFSigs, let us know how we can help you.

73 de w9ctw


Re: ubitx - stop press

Ashhar Farhan
 

i have measurer the input impedance of these stages to be appox 50 ohms when terminated in the 220 resistor in the output. i made these measurements with a homemade return loss bridge and the sweeperino. 
the original wes/kopski amps uses separate resistors for bias and feeback, i used just one. if you want to experiment with different feedback resistors while keeping the bias the same, you could use the original block.
the noise figure should be 14 db. i say that because i havent measured it. i do not have calibrated noise source. this figure is based on the accumulated (measured) losses of the lpf, first mixer and the first if amps figure of 6 db.
connecting the antenna brings up the noise on all bands at my qth. i must, though admit that i havent had any contacts in 28 mhz at all.
- f

On 8 Apr 2017 7:52 p.m., <selfy.dtp@...> wrote:
Farhan,

Let me first thank you for the projects and experience you share with us. I am interested to find out how uBITX behaves in terms of selectivity and sensitivity?

I also support the idea, that if you want to cover all HF band a set of (at least) four LPF for the PA is a must.

Additionally, looking at the uBITX schematic, I couldn't help but notice the bidirectional amps slightly differ form the original idea of W7ZOI and K3NHI. You used different biasing approach, but it appears the input impedance is not 50 ohms. My LTSpice simulations show 90 ohms at 10MHz and 50 ohms at 45MHz. And the "gain" transistor is biased at 15mA. Would you, please, share with us what your idea was for doing these mods.

73 de LZ1NEF



Re: ubitx - stop press

philip yates
 

Wow... Impressive, cannot wait for this.

Am following closely the uBitx. Better get space cleared for it.

Thanks Ashhar


Phil-G7BZD


Re: ubitx - stop press

Ashhar Farhan
 

with the 4 filters you get 3.5, 5, 7,10,14,18,21,24.9 and 29 mhz

- f

On 8 Apr 2017 5:05 p.m., "philip yates" <phil@...> wrote:

How many bands will this cover, and does selecting 80m rather than 40m make a difference.

Still very interested.


Phil G7BZD