Re: QSX 10W HF Linear PA kit
Observations on this Kit, mechanical.I have been assembling this kit today and noticed a couple of things, mechanically, when building. (yet to power up) The drilled tapped holes in the heat-sink, seem to be 'inaccurate '.? When mine is assembled, the IRF510's have to be skewed a little to fit. ie not fitting parallel to the edges of the PCB and heat-sink.? It's most easily noticable by looking at the IRF510 screws are not in the centre of the PCB holes. It would appear the hole holding down the BS170's is not centred in the heat-sink. I'm guessing it varies from heat-sink to heat-sink. Not a deal breaker. The use of the large nut under the BS170's means the PCB does not fit parallel to the heat-sink. ie the large nut end is much lower than the IRF510 height. I 'fixed' this by turning up a new spacer from aluminium rod. I drilled the centre hole to 3mm so that the rubber tube spacer is not required.? Height of the spacer is approx 5.7mm and the diameter is 9.5mm. (The supplied nut is ~4.4mm high.) Another 'fix' would be? a suitable flat washer, on the heat-sink side,. Glenn? vk3pe Pic shows supplied spacer/nut height is lower than the IRF510's height. Pic below, new spacer: Pic below, even height now of the PCB to heat-sink.
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Re: RX trouble Low / BAD Boards?
Ant is OK and already have an off board audio amp, but thanks.? Plan to add AGC after getting hte stock board working... Fixing my freq counter moved ahead of mor ubitx work... Woody -? KZ4AK On 10/26/2018 1:57, Curt via Groups.Io wrote: Woody
check to see if you did not mix up the ground and signal connections at the antenna, as I did at first.
also, if you have an outboard device with an audio amplifier, like the NESCAF here or an amplified speaker - see if that can bring up your audio.
I will share that since the rig does not have AGC -- signals can go from being very loud requiring minimum audio gain to very low requiring all the audio gain.
it does take some patience to get this thing wired correctly - don't ask how many issues I had in integrating the uBITX board into the case from . I am hopeful you will find it is something simple to correct (but not simple to find).
73 Curt
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Re: RX trouble Low / BAD Boards?
thanks for sharing ?but like i said when in cw mode it works like it should in lsb/usb ?and in reverse no sound?
Woody
check to see if you did not mix up the ground and signal connections at the antenna, as I did at first.?
also, if you have an outboard device with an audio amplifier, like the NESCAF here or an amplified speaker - see if that can bring up your audio.?
I will share that since the rig does not have AGC -- signals can go from being very loud requiring minimum audio gain to very low requiring all the audio gain.?
it does take some patience to get this thing wired correctly - don't ask how many issues I had in integrating the uBITX board into the case from .? I am hopeful you will find it is something simple to correct (but not simple to find).?
73 Curt
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Re: RX trouble Low / BAD Boards?
Woody
check to see if you did not mix up the ground and signal connections at the antenna, as I did at first.?
also, if you have an outboard device with an audio amplifier, like the NESCAF here or an amplified speaker - see if that can bring up your audio.?
I will share that since the rig does not have AGC -- signals can go from being very loud requiring minimum audio gain to very low requiring all the audio gain.?
it does take some patience to get this thing wired correctly - don't ask how many issues I had in integrating the uBITX board into the case from .? I am hopeful you will find it is something simple to correct (but not simple to find).?
73 Curt
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Most BITX microphone amp stages are designed for 45 mv to 50 mv input.?
It is possible to change the emitter resistor and emitter bypass to accommodate
variations in microphone output.? Over the years most reasonably priced
Electret mikes have been found to provide this voltage in the BITX circuit.
Arv _._
Also, its a large db span, the one I think I've received. And, much smaller. There are huge differences in microphones and Baofeng and perhaps Ashhar are trying to be extremely economical with their choices.? It would make sense for Ashhar to design the microphone amp "around" the microphones he had samples of and when satisfied order a ton of them. I've got a noise generator and scope and thought of designing a measurement jig for some time. And, remembering that the 70 cent one is most likely about 5 cents in quantity.?
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A - 24 db electret will likely be enough to have plenty of average power without mods. I use the stock element but have made the one resistor mod at the mic input and for me it works well. The stock element might be cheap but when I tried a 4USD and - 44db I have had less power output. I certainly have had a much worse experience with the IC-7000 stock microphone rather than the allegedly cheap stock ubtix element.
Il 25/ott/2018 20:51, "barry halterman" < kthreebo@...> ha scritto: My stock elemet does nothing unless? I blow into it or whistle. pretty lame.
Also, its a large db span, the one I think I've received. And, much smaller. There are huge differences in microphones and Baofeng and perhaps Ashhar are trying to be extremely economical with their choices.? It would make sense for Ashhar to design the microphone amp "around" the microphones he had samples of and when satisfied order a ton of them. I've got a noise generator and scope and thought of designing a measurement jig for some time. And, remembering that the 70 cent one is most likely about 5 cents in quantity.?
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Re: RX trouble Low / BAD Boards?
Jim, Thanks for checking your levels. Pretty close to what I have when re-measured (below).
Looks like I will need to do more detective work.? I was misled by my not so great teat equipment.? Visited a RF engineer friend (N4UA) and we checked with his 100 MHz scope. TP 12, 15, & 18 all measured 700 mV P-P. ? Don't know what is normal -? Perhaps lower than I would have guessed, but present and agrees with Jim.
He wondered if the problem may be in the 12 MHz crystal filter. We agreed that a problem with it could cause the symptoms.? I can say that the filter is rather microphonic.?? Lightly tapping the crystals produced sound in the audio output.? Hard to be certain, but 2 of them seemed more sensitive than the others.
Also...
A signal could be heard on 40M with a 1 uV signal to the antenna port.? Not too bad, but the low audio, tuning and narrow bandpass issues remain.
Need to do more signal tracing and check the center, loss, and bandwith of the filter.? Unfortunately, my frequency counter died a few days ago, so will have to? fix it before I can sweep the filter.
So, the uBITX trouble shooting is going to be on hold until I repair my frequency counter.?? I will be back with a solution (or more questions) when the counter is working and I have more measurements.
Thanks again for all the suggestions - Good to have the support!
For now, this tread is on hold....
Woody,? KZ4AK
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Re: RX trouble Low / BAD Boards?
Ok ...So checked levels with TEK 2215a w/ P6100 probe: TP 12 ....0.78 V P/P ...TP 15 ....0.8 v P/P @ 9.8 Mhz? 0.72 v P/P @ 10.8 Mhz? ....TP 18?? 0.6 v P/P
?into 7A13 SA ....TP 12? -10 dbm ...TP 15?? -5 dbm @ 33 Mhz/ -10 dbm @ 57 Mhz? ...TP 18?? -0 dbm @ 12 Mhz
( the SA 50 ohm input loads the pads down )
0.8 Volts P/P is about 280 mV RMS .,,? (your SG is output is rms so your rf probe is calibrated to rms also)
Jim
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My stock elemet does nothing unless? I blow into it or whistle. pretty lame.
Also, its a large db span, the one I think I've received. And, much smaller. There are huge differences in microphones and Baofeng and perhaps Ashhar are trying to be extremely economical with their choices.? It would make sense for Ashhar to design the microphone amp "around" the microphones he had samples of and when satisfied order a ton of them. I've got a noise generator and scope and thought of designing a measurement jig for some time. And, remembering that the 70 cent one is most likely about 5 cents in quantity.?
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Also, its a large db span, the one I think I've received. And, much smaller. There are huge differences in microphones and Baofeng and perhaps Ashhar are trying to be extremely economical with their choices.? It would make sense for Ashhar to design the microphone amp "around" the microphones he had samples of and when satisfied order a ton of them. I've got a noise generator and scope and thought of designing a measurement jig for some time. And, remembering that the 70 cent one is most likely about 5 cents in quantity.?
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Yes, and why would Ashhar use a -60 when the least expensive possibility might be the same as the 70 cent one at digikey, which is a -44 db .? But, its all a guess until we here something definitive from Ashhar.?
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Re: RX trouble Low / BAD Boards?
Jim, I checked with the RF voltmeter (good to VHF+).? Not sure how accurate it is, but ran my Measurments sig gen into it set to 50,000 uV out.? Voltmeter read 10mv at 58 MHz.? Sig gen set to 100K uV, read 40 mv.?? If the sig gen is still near cal, indicates the Rf voltmeter is reading low at these low levels. Cross checked the sig gen into my log RF power meter...? 100K uV = -10 dbm (70 mv) & 50K uV = -15 dbm (40 mv).?? Sort of close...? The voltmeter diode detector may not be getting turned on well at these levels (?).? The log pwr meter is 50 ohms.? For a point of reference TP18 is reading -47dbm (1 mV) into a 50 ohm load; expect it is loading down the TP.? Wish I had high dollar test gear!? With that in mind, and not knowing how much the voltmeter probe loads the circuit, got these readings... TP 12, Clk2 - 180 mV TP 15, Clk1 - 180 mV TP 18, Clk0 - 300 mV Considering the voltmeter may be rather low, might translate to 400 mV, 400 mV, and 600 mV.? Don't know what the spec is, but seems on the low side.? Will try to measure with a friend's faster scope and report back. Raj, It does transmit OK, both in CW and SSB, but the pwr out is low. Now getting 1 watt on 40M, CW and 4 watts on 20M CW.? Cross checked the dummy load meter against my Elecraft K2.? It is indicating 10 watts from the K2, so should be pretty close.? RX RF sensitivity (and audio out level) are also both low. Still trying to figure this out.?? Thanks for all the suggestions. Woody,? KZ4AK On 10/25/2018 14:16, Woody wrote: Good point Jim.? It is rated within 3db at 35 MHz.?? Didn't expect an accurate reading at 45, but did expect to see something.? Will double check with my RF voltmeter...
Woody? -? KZ4AK
On 10/25/2018 5:07, jim via Groups.Io wrote:
Maybe a dumb question but its gotta be asked ...how fast is your scope?
Clk 0 is 12 Mhz or so
Clk 1 is 45 +/- 12 Mhz (33/57 Mhz)
Clk 2 is 45 Mhz to 75 Mhz
TP1 is directly off the antenna (think microvolts)
Jim
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I have tried different electrets, and one rated at - 44. They are all similar. However the stock element provides more output, I would say around 1-2db more looking at the output power speaking normally. The stock can't be a - 60db .
Il 25/ott/2018 18:11, "Michael Shreeve" < shreevester@...> ha scritto: Also, the on small 30-44 db microphones have arrived and there much smaller than the ones Ashhar supplies, I'd safe half the diameter.?
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Also, the on small 30-44 db microphones have arrived and there much smaller than the ones Ashhar supplies, I'd safe half the diameter.?
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If you look at gain charts, say at Digikey for instance, you will see that -24 db is a very high gain electret element, much higher than most. The average typical element is around -40 db,? the most sensitive is -24db and there are three (by using the term "electret" as the only search term) . It would be nice to know the actual sensitivity and or part number, or have a spec sheet on the original used by Ashhar. I put the question to him, he said he would talk to "his guy" and hasn't gotten back. Bulk from China, that's all we know. One fellow said "-60db" and that would be one of the least sensitive out there. Not sure how he determined that.? No correlation in price, so, perhaps actual flatness and distortion values make a difference. Also, knowing Ashhar does try to purchase inexpensive parts, and pennies make a difference when your selling 10 to 100 k of units, the least expensive , at least at Digikey, were -44 db units. 70 cents. The most expensive, and I'm not including ones without a photo because I can't tell if they are the same physical design, is around $4 for one, and -35dbm . Noise figures vary a lot.? I'm assuming the lowest numbers are the best but do not know. The chart is here .?
I have purchased some "deals" from ebay, and I'll be trying to determine how well they work. One so far, -52db, another,?30-44dB Electret Condenser Microphone High Sensitivity Pickup .?
Haven't tried either yet. Thinking a switched system would be smart for immediate comparisons. Also have the better compression module, and other things. Have had such a powerful signal on 80m that I just haven't felt a high priority need to mess with this. Antennas really make a difference.?
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Re: RX trouble Low / BAD Boards?
Good point Jim.? It is rated within 3db at 35 MHz.?? Didn't expect an accurate reading at 45, but did expect to see something.? Will double check with my RF voltmeter...
Woody? -? KZ4AK
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On 10/25/2018 5:07, jim via Groups.Io wrote: Maybe a dumb question but its gotta be asked ...how fast is your scope?
Clk 0 is 12 Mhz or so
Clk 1 is 45 +/- 12 Mhz (33/57 Mhz)
Clk 2 is 45 Mhz to 75 Mhz
TP1 is directly off the antenna (think microvolts)
Jim
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Re: RX trouble Low / BAD Boards?
Yes, have the v4 with discrete transistor amp.? Will check out the amp info.? Audio was so low at the vol wiper that hardly anything audible when tapped the off board amp from it as an experiment. OTOH, the bigger problem is no (or VERY) low level on CLK 1 & CLK2 from the Raduino.? So low I am surprised it received anything. Woody,? KZ4AK On 10/25/2018 0:56, Skip Davis via Groups.Io wrote: Woody do you have the version 4 board with the discreet audio amp? If so checkout the archives or Wiki page for a fix/mod for the amplifier. There were some builders that had distorted audio output and to me your recordings sound like that audio distortion. If you can inject a carrier input compare your audio signals at the high side of the volume control and then your output. You can also look at the collector of Q71 which should be the same as the volume control only a larger level.
If you have the IC amplifier then the chip maybe bad.
Skip Davis, NC9O
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Re: RX trouble Low / BAD Boards?
Woody does this board transmit OK ?
Try both SSB and CW.
Raj
At 25-10-18, you wrote:
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Will give that a try, but
suspect it is not the source of the problem.?? The speaker out feeds
the top of a 500 ohm potentiometer.?? Adjusting the drive level to
the off board amp with the pot?? (wiper) affects volume available,
but doesn't affect the audio quality.
Attached, FWIW, are two mp3 clips.??
"compare 2 noise" is with the antenna attached, but no signal.
First is the ubitx, followed by the K2. Note: I do have a bit of power
line noise.??
"compare 2" is of a 40M QSO.?? Ubitx first, then the K2.
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Tried the off board amp, tapping into earlier audio stages.?? Input
level so low, could not hear the output
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Still scratching my head!? ?? Compared the ubitx to my Elecraft K2
by switching the antenna to each on a S5 (on K2) signal.?? The RF
sensitivity is not as good as the K2 and (still) shows some
distortion.
WELL, WELL,
WELL...
Pulled out the o'scope and made some measurements.?? I think I have
a bad ubitx.?? I can only get a measurable signal from CLK 0 - TP18
reads 1.3 v PP.? ?? TP15 (CLK 1) and TP12 (CLK 2) are below what I
can measure with a 5mv scale with 10x probe.?? It is a wonder I hear
anything!!!?? Also may explain the super low audio when I do hear
something.?? Probably why the BFO adjustment is really weird
too.
Here is a list of the TPs I have checked (no antenna):
TP 1?? -?? Zero (zero = below readability)
TP 12 -?? Zero?? (CLK 2) No signal either side of R100
either.
TP 14 -?? Zero
TP 15 - Zero?? No signal either side of of R106 either.
TP 18 - (CLK 0)?? 1.3 v PP
Note that "Zero" may have some signal, but below my scope's
measurement capability.
Measured the Raduino directly where it plugs into the main board.
Confirms what I saw above.?? Pin 19 (CLK 0), lots of signal.??
Pin 16 (CLK 1), no signal.?? Pin 13 (CLK 2) no signal.
Looks like I need to contact HFsignals.
Woody, KZ4AK
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I have this done now and it appears to be "all good". But I did it by tweaking until I got it right on. Gordon's advice about using a viewer was good, and I did use the WSJT X software viewer.
This must be about the worst method of aligning a Tx/Rx I have ever seen. Perhaps it wouldn't be so bad if there was some instruction sent with the rig from the factory. It appears there are several methods that might or might not work.?
My next task is to make it CAT capable....
The old TS120S now has a new lease on life. Despite all the talk of the Tranmission being dirty I have not yet see any sign of that practically. I think this is because I use a very low drive level by changing RV 1 to a 50 Kohm pot and limiting output to 100 watts. The TS 120 amplifier has inbuilt filtering too.?
Thanks for your interest.
73 Roger ZL2RX ?
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Re: RX trouble Low / BAD Boards?
Maybe a dumb question but its gotta be asked ...how fast is your scope? Clk 0 is 12 Mhz or so Clk 1 is 45 +/- 12 Mhz (33/57 Mhz) Clk 2 is 45 Mhz to 75 Mhz
TP1 is directly off the antenna (think microvolts)
Jim
On Wednesday, October 24, 2018, 6:00:58 PM PDT, Skip Davis via Groups.Io <skipnc9o@...> wrote:
Woody do you have the version 4 board with the discreet audio amp? If so checkout the archives or Wiki page for a fix/mod for the amplifier. There were some builders that had distorted audio output and to me your recordings sound like that audio distortion. If you can inject a carrier input compare your audio signals at the high side of the volume control and then your output. You can also look at the collector of Q71 which should be the same as the volume control only a larger level.? If you have the IC amplifier then the chip maybe bad.? On Oct 24, 2018, at 16:51, Woody < mailme@...> wrote:
Will give that a try, but suspect it is
not the source of the problem.? The speaker out feeds the top of a
500 ohm potentiometer.? Adjusting the drive level to the off board
amp with the pot? (wiper) affects volume available, but doesn't
affect the audio quality.
Attached, FWIW, are two mp3 clips.? "compare 2 noise" is with the
antenna attached, but no signal. First is the ubitx, followed by
the K2. Note: I do have a bit of power line noise.?
"compare 2" is of a 40M QSO.? Ubitx first, then the K2.
--------------
Tried the off board amp, tapping into earlier audio stages.? Input
level so low, could not hear the output
-----------------
Still scratching my head!?? Compared the ubitx to my Elecraft K2
by switching the antenna to each on a S5 (on K2) signal.? The RF
sensitivity is not as good as the K2 and (still) shows some
distortion.
WELL, WELL, WELL...
Pulled out the o'scope and made some measurements.? I think I have
a bad ubitx.? I can only get a measurable signal from CLK 0 - TP18
reads 1.3 v PP.?? TP15 (CLK 1) and TP12 (CLK 2) are below what I
can measure with a 5mv scale with 10x probe.? It is a wonder I
hear anything!!!? Also may explain the super low audio when I do
hear something.? Probably why the BFO adjustment is really weird
too.
Here is a list of the TPs I have checked (no antenna):
TP 1? -? Zero (zero = below readability)
TP 12 -? Zero? (CLK 2) No signal either side of R100 either.
TP 14 -? Zero
TP 15 - Zero? No signal either side of of R106 either.
TP 18 - (CLK 0)? 1.3 v PP
Note that "Zero" may have some signal, but below my scope's
measurement capability.
Measured the Raduino directly where it plugs into the main board.
Confirms what I saw above.? Pin 19 (CLK 0), lots of signal.? Pin
16 (CLK 1), no signal.? Pin 13 (CLK 2) no signal.
Looks like I need to contact HFsignals.
Woody, KZ4AK
On 10/24/2018 16:27, Richie Chambless wrote:
Woody?
I just listened to your sound clips and I heard distortion that¡¯s
usually produced when a source signal overdrives the next stage.
Where are you connecting your outboard amp? I would think that you
would get distortion if you connected it to the speaker out (8 ohm
impedance). I would tap the audio at the volume pot (top lug) if
you haven¡¯t already.?
<compare 2 noise.mp3>
<compare 2.mp3>
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Michael Shreeve
Raj vu2zap