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I just got the ubitx and wired it up.
I was able to use a signal generator to hear a signal on 7.150MHZ that sounded good.? But listening to a station that sounded good on my regular radio I could hear it clearly but ubitx on the same antenna it was a bit weaker signal and hard to understand.
I noticed it use about 150ma just powering up for the smoke test which isn't within the documented limits.
I noticed base of Q12 has more than the documented voltage at a little over 10 volts which is above what is expected.
The two antenna pins I noticed only have about 1.8 ohm resistance not sure if that is normal, continuity tests show that as basically shorted to ground.
I noticed the K3 relay seems different than the other relays pin 9 seems shorted to pin 5.? (K3 Pin 9 Seems like the only pin of all the relays that is grounded)
K3 pins 5 and 3 seem shorted as you would expect.
I noticed all of the other relays: 12 and 5 shorted, 14 and 3 shorted and 16 and 1 show shorted but on K3 12 and 5, 14 and 3 and 16 and 1 aren't showing as connected? (they show about 10k resistance except for 16 and 1 that don't show connected at all.
Is there a K3 relay issue here perhaps or is that normal for that relay?
Any other ideas for receive strength improvement/checks?
Thanks.
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Dave
Listen to a few more signals. Ubitx has no AGC. Weak signals require cranking the volume up. Also a good antenna will beat a piece of short wire. Try headphones and several signals. Its a nice receiver, just different than commercial norm.
Its possible bfo might need adjustment, mine did. But get some more data.
Curt
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Thanks giving it a try.? Tuning around can't really get a decent signal on 40 meter or 20 meter.? I tried using a full half wave fan dipole on 40m/20m.? ?Testing at 5 watts from my nearby radio it's ubitx gets a strong? signal its intelligible but very muddy.
Weak signals are all pretty weak and hard to copy.? I'll try a bit more and maybe give the BFO a try.
Thanks.
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Hi Dave,
Check the schematics. The antenna terminal has a DC short to ground through an inductor. I have not looked at the other items you listed there but I would not be surprised to find the windings of an inductor across those too. Those relay terminals wouldn't happen to be the relay coils would they? If not, then look where they connect forother inductors or small resistors.
If you were able to receive signals at all then your antenna terminal and others are not shorted to grouns (for rf).
73,
Bill KU8H
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On 12/15/18 2:28 PM, Dave Space wrote: I just got the ubitx and wired it up.
I was able to use a signal generator to hear a signal on 7.150MHZ that sounded good.? But listening to a station that sounded good on my regular radio I could hear it clearly but ubitx on the same antenna it was a bit weaker signal and hard to understand.
I noticed it use about 150ma just powering up for the smoke test which isn't within the documented limits.
I noticed base of Q12 has more than the documented voltage at a little over 10 volts which is above what is expected.
The two antenna pins I noticed only have about 1.8 ohm resistance not sure if that is normal, continuity tests show that as basically shorted to ground.
I noticed the K3 relay seems different than the other relays pin 9 seems shorted to pin 5.? (K3 Pin 9 Seems like the only pin of all the relays that is grounded)
K3 pins 5 and 3 seem shorted as you would expect.
I noticed all of the other relays: 12 and 5 shorted, 14 and 3 shorted and 16 and 1 show shorted but on K3 12 and 5, 14 and 3 and 16 and 1 aren't showing as connected? (they show about 10k resistance except for 16 and 1 that don't show connected at all.
Is there a K3 relay issue here perhaps or is that normal for that relay?
Any other ideas for receive strength improvement/checks?
Thanks.
--
bark less - wag more
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Ah you are right I do see that short to ground through the inductor.? ? I can receive signals but they are so low they are almost unintelligible and hard to sound centered on.? Tried the BFO but its as good as it gets on the default.? I tried some different earphones but still no luck? signal either can't be heard or if it can be it's hard to hear.
Tried hooking up a speaker but don't hear anything out of it (have to check if it's hooked up right or drive.)? It sounds to be like there is not enough RF gain perhaps though the noise level is already pretty high so no sure if more gain would make it easier to hear.
I've listened to some folks with their ubitx on youtube and they can send crystal clear and loud enough but mine doesn't seem to have those qualities.? Mostly hard to pick up anything, even on the strongest remote signals not very clear.? Trying with a close radio at 5 watts its a lot louder as expected and clearer but still pretty muddy but intelligible.
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If you have a version 4 board low audio seems to be a standard. You can make, or buy a small audio amp or use this fix:?
Iam not started my build yet but I do read a lot.
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Dave,
Your issues are similar to mine.? Low and distorted audio and lack
of RF sensitivity.?? I never fully resolved the situation.? Tried
tracing the receive signal with a good scope, but there was too
much garbage (no matter where I grounded the probe) to observe
changes in the RX signal.? My solution was brute force...?
Audio:? I bypassed the audio PA section and fed the volume pot
wiper to an opamp preamp, then to a ~2 watt audio PA chip.? Plenty
of not too distorted audio now.
RF:? Built a preamp with attenuator (for AGC).? Used a low noise
MMIC for the amp followed by a pin diode (pie) attenuator.? The
attenuator works great on a manual control pot.?? Have it working
with an audio derived AGC amp now, but that really needs more work
since it attacks a bit slowly and has some pumping on very strong
signals. I long for one of the old, discontinued Plessey AGC ICs.?
I have one in an old homebrew rig and it is great.?
I posted more info on the RF amp / Attn. several days ago...?
Subject: ? ? 
Good Luck,
Woody
On 12/15/2018 21:31, Dave Space wrote:
Ah you are right I do see that short to ground through the
inductor.? ? I can receive signals but they are so low they are
almost unintelligible and hard to sound centered on.? Tried the
BFO but its as good as it gets on the default.? I tried some
different earphones but still no luck? signal either can't be
heard or if it can be it's hard to hear.
Tried hooking up a speaker but don't hear anything out of it (have
to check if it's hooked up right or drive.)? It sounds to be like
there is not enough RF gain perhaps though the noise level is
already pretty high so no sure if more gain would make it easier
to hear.
I've listened to some folks with their ubitx on youtube and they
can send crystal clear and loud enough but mine doesn't seem to
have those qualities.? Mostly hard to pick up anything, even on
the strongest remote signals not very clear.? Trying with a close
radio at 5 watts its a lot louder as expected and clearer but
still pretty muddy but intelligible.
_._,_._,_
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Also did a careful calibration and BFO adjustment - several times ;) Woody On 12/15/2018 21:31, Dave Space wrote: Ah you are right I do see that short to ground through the inductor.? ? I can receive signals but they are so low they are almost unintelligible and hard to sound centered on.? Tried the BFO but its as good as it gets on the default.? I tried some different earphones but still no luck? signal either can't be heard or if it can be it's hard to hear.
Tried hooking up a speaker but don't hear anything out of it (have to check if it's hooked up right or drive.)? It sounds to be like there is not enough RF gain perhaps though the noise level is already pretty high so no sure if more gain would make it easier to hear.
I've listened to some folks with their ubitx on youtube and they can send crystal clear and loud enough but mine doesn't seem to have those qualities.? Mostly hard to pick up anything, even on the strongest remote signals not very clear.? Trying with a close radio at 5 watts its a lot louder as expected and clearer but still pretty muddy but intelligible.
--
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Hi,
How did you do with the "calibration" process?
73,
Bill KU8H
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On 12/15/18 4:31 PM, Dave Space wrote: Ah you are right I do see that short to ground through the inductor. I can receive signals but they are so low they are almost unintelligible and hard to sound centered on.? Tried the BFO but its as good as it gets on the default.? I tried some different earphones but still no luck signal either can't be heard or if it can be it's hard to hear.
Tried hooking up a speaker but don't hear anything out of it (have to check if it's hooked up right or drive.)? It sounds to be like there is not enough RF gain perhaps though the noise level is already pretty high so no sure if more gain would make it easier to hear.
I've listened to some folks with their ubitx on youtube and they can send crystal clear and loud enough but mine doesn't seem to have those qualities.? Mostly hard to pick up anything, even on the strongest remote signals not very clear.? Trying with a close radio at 5 watts its a lot louder as expected and clearer but still pretty muddy but intelligible.
--
bark less - wag more
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I agree with Curt, the BFO might need adjustment.? Here is the link to HF Signals reccommended tune up page:
To check on the relays, I would refer back to the schematic in the circuit description:
Hope this helps
73 Evan AC9TU
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Just checking something,
Woody and Dave, when you do your BFO adjustment, you know you to adjust both the BFO and the tuning of the receiver?? You can't just stay on one exact frequency as you adjust it, you need to fine tune a bit with each move of the BFO freqency to see how clear each setting is.
Another way to adjust it at the start is to do it "by ear".? Just tune to background static only. ? If the background static is low pitched, muffled and hollow sounding, the BFO is set too close to center.? If the background static consists of only very high pitched sounds, then it is too far away.? Aim for something in between to start with.
A really good method is just putting the receiver on a frequency with no signal again, record the background static, then use Audacity to analyze the spectrum. This will show you where the BFO bandwidth is set.? You want it around 300Hz to 2700Hz.
I think the "Spectrogram" program can do this live, instead of having to make a recording each time.
73,
Mark.
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Thanks didn't know that but retried. Still signals seem very faint/garbled.? Even tuning around things don't get better.? Seems like it just can't pull the signals out of the noise.
I can tune something on my regular rig and it's clear as day and using the same antenna hear nothing on the ubitx.
I can't do the mic tuning part yet I didn't get my mic hooked up yet.
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Thanks, interesting.? May have to think about something like that since it just doesn't want to hear much at the moment.
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I used a 'random noise source' and Spectrogram? (maybe still? available on ELECRAFT K2 website)
On Saturday, December 15, 2018, 3:36:16 PM PST, Mark McNabb <n7eku@...> wrote:
Just checking something,
I think the "Spectrogram" program can do this live, instead of having to make a recording each time.
73,
Mark.
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This is a great idea/process when used with the CEC sw and memory manager.? One thing I did do was find an offline program:
Was real easy to use a usb mic as input to the program on Windows 10.
Really improved the receive quality for my v4 ubitx.? Right after I was able to contact Florida from Chicago using only a OCFD in my attic.
73
Evan
AC9TU
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Does any one have their oscilloscope peak to peak volts measurements for the receive transistors (with a specific signal generator volts/ of of course)???
Q10,11,12 base and collector and Q30,31,32?
I can measure and post mine.? I noticed their is very minimal gain at Q10 and Q30, almost so small my scope can't really see much difference.
(My scope only goes down to 20mv/div I think)
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Pretty much according to the instructions...? Set the CAL to zero beat against my 20 MHz reference standard.? Then adjusted the BFO until got a good RX signal.? First used a signal from another local SSB rig tuned to the same freq.? Then tweaked a bit more listening to on the air signals...
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On 12/15/2018 22:48, Bill Cromwell wrote: Hi,
How did you do with the "calibration" process?
73,
Bill? KU8H
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That should be 'good enough'. You might have to pay a little more attention if you want to use the rig in a frequency measuring contest. That isn't necessary for just everyday operating.
73,
Bill KU8H
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On 12/16/18 11:37 AM, Woody wrote: Pretty much according to the instructions...? Set the CAL to zero beat against my 20 MHz reference standard.? Then adjusted the BFO until got a good RX signal.? First used a signal from another local SSB rig tuned to the same freq.? Then tweaked a bit more listening to on the air signals...
On 12/15/2018 22:48, Bill Cromwell wrote:
Hi,
How did you do with the "calibration" process?
73,
Bill? KU8H
--
bark less - wag more
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Format: No Signal,(comma) Signal peak to peak volts (i.e. 1 mv (no signal) , 2mv signal generator on)
Input 7.150MHZ signal 1khz deviation 30 mv at antenna direct connection
Q10??
b 70mv, 70 mv
c 8mv,? 10mv
~50MHZ
Q11
b 12mv, 14mv
c 100mv, 108mv
Q12
b 16mv, 12mv
c 114mv, 120mv
Q30
b 64mv, 130mv
c 24mv, ? (have to go back and measure)
6-35MHZ
Q31
b 24mv, 32mv
c 75mv, 220mv
?11-32MHZ
Q32
b 22mv, 22mv
c 88mv, 230mv
6-50MHZ
Q71 was interesting could see a double helix sine wave on one of the terminals
b 430mv, 15 volts
c 32mv, 65mv
32-50MHZ range
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Hi Dave,
Did I miss something? Deviation is an FM measurement unit. I didn't notice that you are using your uBitx for FM. Are you doing that with SDR software?
73,
Bill KU8H
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On 12/16/18 1:22 PM, Dave Space wrote: Format: No Signal,(comma) Signal peak to peak volts (i.e. 1 mv (no signal) , 2mv signal generator on)
Input 7.150MHZ signal 1khz deviation 30 mv at antenna direct connection
Q10
b 70mv, 70 mv
c 8mv,? 10mv
~50MHZ
Q11
b 12mv, 14mv
c 100mv, 108mv
Q12
b 16mv, 12mv
c 114mv, 120mv
Q30
b 64mv, 130mv
c 24mv, ? (have to go back and measure)
6-35MHZ
Q31
b 24mv, 32mv
c 75mv, 220mv
?11-32MHZ
Q32
b 22mv, 22mv
c 88mv, 230mv
6-50MHZ
Q71 was interesting could see a double helix sine wave on one of the terminals
b 430mv, 15 volts
c 32mv, 65mv
32-50MHZ range
--
bark less - wag more
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