Date   
uBITX - super touchy low end volume #ubitx-help #ubitx

Rob French (KC4UPR)
 

Super excited, just put together my uBITX and love it, though I haven't successfully managed any 2-way QSOs yet.  I've got a few spots on RBN, so I know something's getting out... Anyway...

I've noticed that the volume control (I'm using the stock potentiometer) is super sensitive at the low end.  i.e. As soon as I turn it on, I never turn it more than about 1/4 turn.  And if I go more, it distorts super quickly.  Very small adjustments of the knob change the volume pretty drastically.  I actually wondered if I wired the pot backwards!  But, I checked against the schematic and also this page ( https://ubitx.net/wiring-up-the-volume-control/ ), and as far as I can tell, I've done it right (green, orange, yellow, from L to R).  Any other thoughts?

Thanks!
Rob KC4UPR

Re: Issues with ordering the BITX40

Gordon Gibby <ggibby@...>
 

Fantastic!!!    


On Aug 2, 2019, at 20:52, Ashhar Farhan <farhanbox@...> wrote:

I think that paypal has tweaked something and the old style button had stopped working. I will fix the raduino too.
- f

On Sat 3 Aug, 2019, 3:17 AM Jerry Gaffke via Groups.Io, <jgaffke=yahoo.com@groups.io> wrote:
While you are at it, include a way to buy a Raduino.
That option seems to have disappeared from hfsignals.com

On Thu, Aug 1, 2019 at 07:21 PM, Ashhar Farhan wrote:
Yup,  'Group, we have a problem'. I will fix this Paypal trouble in 24 hours. Aah, the joys of Paypal customer service, here we go again...
- f

Re: Cool cheap oscilloscope for troubleshooting

Tom, wb6b
 

On Fri, Aug 2, 2019 at 01:08 PM, Mark Hatch wrote:
take a look at EspoTek Labrador.
That is an interesting little board. I may buy one when I budget out an interesting gadget buy.

On a related note:

Here is another "universal" lab tool (maybe a little more RF focused) in the same style as the "Analog Discovery" module. But it is not cheap.
https://www.redpitaya.com

Was reminded of this when I was following another thread on the Software Controlled Ham Radio group.
https://groups.io/g/SoftwareControlledHamRadio/messages

Tom, wb6b

Re: amatureradiokits enclosure question #ubitx-help #ubitx

Dexter N Muir
 

Looks like a board hand-redrilled for correction post-manufacture: quality-control rework? or are they all hand-drilled? J2 pin 4 and the centre pin of J5 are out of line, too.
ZL2DEX who used to prototype PCBs with NC Driil.

Re: amatureradiokits enclosure question #ubitx-help #ubitx

Mark Hatch
 

I didn’t have to cut any pins in my two kits...  strange how those holes are not aligned...


I agree with Dexter,  looks like this was done by hand.

73
mark

Re: amatureradiokits enclosure question #ubitx-help #ubitx

Ian Reeve
 

Some are out of alignment on my boards but all the holes are there.Just bear in mind that on my boards I had to add a jump link to give both channels on the headphone socket.As it stands you will only get audio on one side..


From: BITX20@groups.io <BITX20@groups.io> on behalf of Mark Hatch <mark2382@...>
Sent: Saturday, August 3, 2019 7:21:25 AM
To: BITX20@groups.io <BITX20@groups.io>
Subject: Re: [BITX20] amatureradiokits enclosure question #ubitx #ubitx-help
 
I didn’t have to cut any pins in my two kits...  strange how those holes are not aligned...


I agree with Dexter,  looks like this was done by hand.

73
mark

Re: Cool cheap oscilloscope for troubleshooting

David Wilcox
 

Tom,

I guess I need more hand holding and pictures.  A friend came over with his new Rigol scope to help me once and and had a slew of attenuators, tees, and other stuff so he didn’t wreck his scope.  I will need a list of these things to prevent damaging a new scope too. The few basic scope videos and books I have read assume I know how to hook it up. The only one that makes sense is Hans video on using the 200 kHz pocket scope for checking the audio circuits on the QCX.  but that was very low power and no risk of damage.  I want to check RF output as well as other things.

Will look through the Digilent manual with more attention.  I was looking for an A, B, C this is how you do this kind of book for 3 rd graders.....Ha!

Thanks.

Dave K8WPE

David J. Wilcox K8WPE’s iPad

On Aug 2, 2019, at 8:43 AM, Tom, wb6b <wb6b@...> wrote:

On Thu, Aug 1, 2019 at 02:39 AM, David Wilcox wrote:
 The reference manual reads like a college text book
Hi,

I've looked at the "Analog Discovery" Digilent scopes. I can understand why the manual would be a densely packed tome. The Analog Discovery is nearly a universal device and the whole universe of what is does as well as how to create those universes is likely covered in the manual. 

So for a beginner you have to take a big bite to get through it.

However, if you just pick out one thing, the simplest examples that hopefully exist in the manual of how to look at analog analog waveforms and go with that for now, likely you can have some success and fun learning how to use an Oscilloscope. Even though the scope first requires you to understand how to make the circuitry in the Digilent device to "assemble" itself into an oscilloscope by doing something from the control software to upload the "scope circuitry" to the Digilent device.

If you stick with the "Analog Discovery" module it looks like you can get a lot of mileage out of it as you learn more.  Hopefully, there are videos that users of the device have put up in an effort to help others use it. Once you get through that you should be able to relate the instructions/videos on more generic scopes to what to do on the Digilent scope.

Tom, wb6b

Re: KD8CEC - Nextion Display - IAN questions

MVS Sarma
 

After Very long gap, i had observed this noise. 
I placed a 2.2mH rf choke in series to 5v line going to nextion . At nextion 5v and Gnd terminals i placed 220uF. The noise reduced to just10%.

Re: uBITX - super touchy low end volume #ubitx-help #ubitx

Edward Reynolds
 

I’d look at the picture on the HFsignals site uBITX wire up section for volume control and compare your connections with picture. Otherwise no answer other than a bad volume controller. Good luck
Ed de N7SNT 


On Aug 2, 2019, at 6:32 PM, Rob French (KC4UPR) <robert@...> wrote:

Super excited, just put together my uBITX and love it, though I haven't successfully managed any 2-way QSOs yet.  I've got a few spots on RBN, so I know something's getting out... Anyway...

I've noticed that the volume control (I'm using the stock potentiometer) is super sensitive at the low end.  i.e. As soon as I turn it on, I never turn it more than about 1/4 turn.  And if I go more, it distorts super quickly.  Very small adjustments of the knob change the volume pretty drastically.  I actually wondered if I wired the pot backwards!  But, I checked against the schematic and also this page ( https://ubitx.net/wiring-up-the-volume-control/ ), and as far as I can tell, I've done it right (green, orange, yellow, from L to R).  Any other thoughts?

Thanks!
Rob KC4UPR

Re: uBITX - super touchy low end volume #ubitx-help #ubitx

kg9hfrank@gmail.com
 

Audio taper needed?
de Frank KG9H

On Aug 3, 2019, at 7:26 AM, Edward Reynolds via Groups.Io <n7snt@...> wrote:

I’d look at the picture on the HFsignals site uBITX wire up section for volume control and compare your connections with picture. Otherwise no answer other than a bad volume controller. Good luck
Ed de N7SNT 


On Aug 2, 2019, at 6:32 PM, Rob French (KC4UPR) <robert@...> wrote:

Super excited, just put together my uBITX and love it, though I haven't successfully managed any 2-way QSOs yet.  I've got a few spots on RBN, so I know something's getting out... Anyway...

I've noticed that the volume control (I'm using the stock potentiometer) is super sensitive at the low end.  i.e. As soon as I turn it on, I never turn it more than about 1/4 turn.  And if I go more, it distorts super quickly.  Very small adjustments of the knob change the volume pretty drastically.  I actually wondered if I wired the pot backwards!  But, I checked against the schematic and also this page ( https://ubitx.net/wiring-up-the-volume-control/ ), and as far as I can tell, I've done it right (green, orange, yellow, from L to R).  Any other thoughts?

Thanks!
Rob KC4UPR

Re: amatureradiokits enclosure question #ubitx-help #ubitx

Edward Reynolds
 

I read this blog for information and you just provided something new about the audio board I was unaware of, the fact that the headphone circuit on the board lacked a trace to provide audio to both sides of a stereo headset. In final stages of uBITX construction so would have found it eventually, thanks for the heads up
Cheers
Ed de: n7snt 


On Aug 3, 2019, at 1:19 AM, Ian Reeve <ian.radioworkshop@...> wrote:

Some are out of alignment on my boards but all the holes are there.Just bear in mind that on my boards I had to add a jump link to give both channels on the headphone socket.As it stands you will only get audio on one side..


From: BITX20@groups.io <BITX20@groups.io> on behalf of Mark Hatch <mark2382@...>
Sent: Saturday, August 3, 2019 7:21:25 AM
To: BITX20@groups.io <BITX20@groups.io>
Subject: Re: [BITX20] amatureradiokits enclosure question #ubitx #ubitx-help
 
I didn’t have to cut any pins in my two kits...  strange how those holes are not aligned...


I agree with Dexter,  looks like this was done by hand.

73
mark

Re: uBITX - super touchy low end volume #ubitx-help #ubitx

Rob French (KC4UPR)
 

Yeah, I thought about that, but from what I can tell, the stock pot is audio taper.  I measure it at a few points w/ my multimeter and it seemed to fit a log profile. 

uBITX finals get hot very fast #ubitx-help #ubitx #v5

Rob French (KC4UPR)
 

I've got a new uBITX v5.  I've only been using it for CW so far (haven't gotten around to wiring up the mic yet), but I've noticed that, after calling CQ a half dozen times, the finals get way hot... too hot to hold my finger on for more than a second or so.  

As far as I can tell, my antenna is good to go... according to my antenna analyzer, < 2:1 SWR across 40 meters, which is where I'm using it currently.  I guess I could try doing the same thing into a dummy load to verify that it's not due to an SWR problem.  

Other than loading the KD8CEC firmware and making some firmware configuration settings, I have not deviated from the stock configuration--same finals, same heatsinks, no change to PA bias settings.  

I'm assuming this is not normal.  Any thoughts on resolution?  I'm using a metal case that doesn't quite let me mount the board close enough to back to bolt the finals to the back panel, but I've thought of making a hole in the back panel to accomodate bolting on a larger heatsink.  But I'm also thinking that there may be bigger underlying problem that I address, regardless of whether or not I add a bigger heatsink, fan, etc.

Things I'm thinking I should do:
- Recreate my CQ calling into a dummy load, see how hot they got (does anyone have any metrics for key-down time versus temperature?)
- Measure the current draw on transmit, and/or perform the PA bias calibration from the HF Signals web site
- Build one of those LED SWR meters to back-up my antenna analyzer
- Any other thoughts?

Re: uBITX finals get hot very fast #ubitx-help #ubitx #v5

Clark Martin
 

What is the idle current into the PA with the mic PTT pressed (or the equivalent)?  It should be 400 mA max.  That’s measuring the power just into the PA section.  The radio as a whole should be 500mA max.

How much power out are you getting on CW?



Clark Martin
KK6ISP

On Aug 3, 2019, at 7:50 AM, Rob French (KC4UPR) <robert@...> wrote:

I've got a new uBITX v5.  I've only been using it for CW so far (haven't gotten around to wiring up the mic yet), but I've noticed that, after calling CQ a half dozen times, the finals get way hot... too hot to hold my finger on for more than a second or so.  

As far as I can tell, my antenna is good to go... according to my antenna analyzer, < 2:1 SWR across 40 meters, which is where I'm using it currently.  I guess I could try doing the same thing into a dummy load to verify that it's not due to an SWR problem.  

Other than loading the KD8CEC firmware and making some firmware configuration settings, I have not deviated from the stock configuration--same finals, same heatsinks, no change to PA bias settings.  

I'm assuming this is not normal.  Any thoughts on resolution?  I'm using a metal case that doesn't quite let me mount the board close enough to back to bolt the finals to the back panel, but I've thought of making a hole in the back panel to accomodate bolting on a larger heatsink.  But I'm also thinking that there may be bigger underlying problem that I address, regardless of whether or not I add a bigger heatsink, fan, etc.

Things I'm thinking I should do:
- Recreate my CQ calling into a dummy load, see how hot they got (does anyone have any metrics for key-down time versus temperature?)
- Measure the current draw on transmit, and/or perform the PA bias calibration from the HF Signals web site
- Build one of those LED SWR meters to back-up my antenna analyzer
- Any other thoughts?

Re: uBITX finals get hot very fast #ubitx-help #ubitx #v5

Curt
 

Numerous opinions here, I run my v4 on cw or ssb without updates. I will add a small fan before doing digital modes, whether its needed or not.

Wait until you discover the hot regulator on the raduino. If your PA heatsink is less warm, I suggest things are okay. If it is warmer, then check out bias current, carefully follow instructions.

Curt

Re: uBITX finals get hot very fast #ubitx-help #ubitx #v5

Tom, wb6b
 

Hi,

I found when running digital modes, particularly WSPR, that a fan was a necessity. 

Tom, wb6b

Re: Cool cheap oscilloscope for troubleshooting

Tom, wb6b
 

On Sat, Aug 3, 2019 at 02:01 AM, David Wilcox wrote:
had a slew of attenuators, tees, and other stuff
Hi,

As long as you are sticking to QRP levels (12 wats or less) like the uBITX you should be able to probe the RF circuits with a 10X scope probe. That would be about 35 volts P-P at the output into a 50 ohm dummy load. Probing the PA Mosfets might be iffy. 

I have some generic P6100 (100 Mhz) probes available on eBay and such. The voltage rating (RMS?) rapidly drops from 600VAC to around 30VAC above 1 Mhz.

The scope probe will cause some loading to circuits that could affect them at RF frequencies.

For anything above a Mhz or so you want to always use the scope probe in the 10X mode. In the 1X setting scope probes only have a few Mhz bandwidth, while in the 10X mode the have the rated bandwidth (in this case 100Mhz).

What may seem interesting to some is that scope probes handle frequencies of 100 MHZ or more and they seem to violate all the rules about transmission lines and impedance matching. So how does a scope probe work at 100Mhz when it is not terminated at the impedance of the coax cable that runs from the probe to the input of the scope? The scope probably is terminating the probe cable at 1M ohm, not 50 ohm, for example. 

The secret is the center wire in a scope probe cable is a thin high resistance wire. The resistance of the wire, as it runs through the center of the cable, provides a distributed damping of the reflections that would normally be present in a normal coax cable. It may have been some genius engineer at Tektronix that figured this out. If you measure the scope probe resistance from the probe tip to the center conductor of the BNC connector you will measure 100 ohms or more. So much for scope probe trivia.

As you are just starting out, you may want to begin by trying out the low frequency, low voltage examples you mentioned before venturing off the the RF power stages of your radio. On receive, go for it. Probe the IF stages, mixers, audio, output of the frequency synthesizers, whatever you want. Even at 10X the probe may put enough of a load to detune something, or lower the amplitude of a signal, but most likely it will be fine. You will not be able to accurately measure signals above the frequency capability of the scope.

Tom, wb6b

Elmer Needed

mtngentleman@...
 

Hi All
I have been following this group for some time and have begun assembling a Britx 40
I am sure I will encounter problems and have questions.
Rather then bother the whole group is there someone with experience I might contact directly?

Tks
Shep AA7MH

Re: Cool cheap oscilloscope for troubleshooting

JohnR
 

Dave 
I know meny hams that are looking for the same thing. I know that I could benefit from a simple how to use a scope manual or youtube and it would really help in building and tuning circuits. If you ever find it please post so all us non electronic techs can learn to.
73
John kg4vhv

--

“A single light can banish the darkness”

Lux e tenebris 

"A fool stares at the finger that points at the moon"
I Ching



Re: uBITX finals get hot very fast #ubitx-help #ubitx #v5

Rob French (KC4UPR)
 

All good questions!  So, I don't have a power meter, but I do have a QRP Labs dummy load that has a diode for rudimentary RF power measurements with a voltmeter.  I'll try with that, which will also help me verify that the PA's heat up similarly with the dummy load.

I'll measure the overall current consumption of the transceiver as well as the PA section.  

However, one thing I've discovered... I'm using an old Micronta 12V power supply (that's what the front panel says).  When I checked the back panel, it says 13.8VDC output on the spec label, and measured, it's actually like 14.4V.  (I'll double-check that under load.)  So I imagine the higher supply voltage could also be contributing? 

I'm going to wire up a couple diodes in series with the power supply to bring the supply voltage down to ~12V, and see how that affects things.  Then I'll look at the PA section.

Thanks!
-Rob