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Ham Radio Circuits and Repair / Re: Kenwood TS-140s strange receive audio issue has me confuzzled.
« on: October 13, 2017, 10:05:12 PM »
Lookie what I found on the signal trace going into K6. Hmmmm interesting .....
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Ham Radio Circuits and Repair / Kenwood TS-140s strange receive audio issue has me confuzzled.
« on: October 11, 2017, 11:59:47 PM »
I have an issue in my Kenwood TS-140s that has me a bit puzzled. Whenever I tune to anything between 4.000Mhz and 7.499Mhz, the radio has very low audio. The weird thing is that if I tap the PTT or turn the send/recieve switch on/off, the audio comes up and usually stays up until I go to another band and come back.
Tonight I started digging and believe I've narrowed it down to something funky with the signal path through K5 and K6 on the filter board. The notation on the schematic indicates that these relays switch on the frequency range of my problem.
Voltages at the source (IC1 on the signal board), connectors, and relays are all good and match voltages measured on the other relays. But i know that does not necessarily mean the relays are latching.
Something else that I noticed is that when I touch any of the even numbered relays (output side) including K16, the audio sometimes changes either up or down but this does not happen on the odd numbered (antenna side) relays. Also lightly touching the board with my finger in random places will change the audio. All of this only happens when tuned between 4.000 and 7.499.
I'm thinking about pulling the board and swapping K5 and K6 with K7 and K8 (one at a time) and see if the problem follows the relay(s). If it does, I'll order the relay(s), but if not, what else should I check? Or is there something els I should check before trying a relay swap?
Filter unit schematic is attached for reference.
Tonight I started digging and believe I've narrowed it down to something funky with the signal path through K5 and K6 on the filter board. The notation on the schematic indicates that these relays switch on the frequency range of my problem.
Voltages at the source (IC1 on the signal board), connectors, and relays are all good and match voltages measured on the other relays. But i know that does not necessarily mean the relays are latching.
Something else that I noticed is that when I touch any of the even numbered relays (output side) including K16, the audio sometimes changes either up or down but this does not happen on the odd numbered (antenna side) relays. Also lightly touching the board with my finger in random places will change the audio. All of this only happens when tuned between 4.000 and 7.499.
I'm thinking about pulling the board and swapping K5 and K6 with K7 and K8 (one at a time) and see if the problem follows the relay(s). If it does, I'll order the relay(s), but if not, what else should I check? Or is there something els I should check before trying a relay swap?
Filter unit schematic is attached for reference.
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Other Electronics and repair / Weird signal received on my ham radio(s)
« on: August 03, 2017, 08:01:09 PM »
Here's something weird. A while back my daughter bought a device that cures "gel" nail polish using LED light. Weird right?
anyway, the night she bought it I started getting a click tick click tick click tick click tick click tick click tick in my radio on every band, both antennas and every HF radio I could find. Anyway, I tracked it down to this nail dryer thing and as soon as I unplugged it the noise stopped. The noise happens when the device is just plugged in and idle. When the button on it is pushed, the LEDs light up for 10-45 seconds and the click goes away for that amount of time.
anyway, the night she bought it I started getting a click tick click tick click tick click tick click tick click tick in my radio on every band, both antennas and every HF radio I could find. Anyway, I tracked it down to this nail dryer thing and as soon as I unplugged it the noise stopped. The noise happens when the device is just plugged in and idle. When the button on it is pushed, the LEDs light up for 10-45 seconds and the click goes away for that amount of time.
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Test Equipment / RCP Tube and set tester
« on: July 21, 2017, 09:55:33 PM »
Just got this back up and running. New cord and one wax cap and she's ready to go.
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Electronic Video Blog / Re: #107 Email Q&A FT 747 problem - Which scope to get
« on: April 06, 2017, 03:10:18 PM »
Now for my next question .... What's your opinion on these USB digital scopes like the OWON or Hantek? At the moment I only have the single channel Leader, but I'm getting to where I need 2 channels. Plus it would be nice to have some of the digital scope features. But as usual, I don't have a lot of cash to lay out for a scope.
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Electronic Video Blog / Re: #107 Email Q&A FT 747 problem - Which scope to get
« on: April 06, 2017, 03:05:43 PM »
Not sure if I told you, but this problem is solved. In the end, it was the four 0.5uf 1.5KV caps in the HV rectifier that fixed it. Thanks for the help.
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Equipment Review / Re: Transel Transalyzer MarkIII
« on: March 31, 2017, 05:08:29 PM »
Looking closer at the documentation it does outline calibration procedures and gives a block diagram. There's no schematic, but I should be able to manage.
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Equipment Review / Re: Transel Transalyzer MarkIII
« on: March 31, 2017, 09:08:22 AM »
Either an intermittent problem or operator error 
. I was at my brother's house at the time and didn't spend a lot of time troubleshooting at that time.
Now it's time to recap.
. I was at my brother's house at the time and didn't spend a lot of time troubleshooting at that time.Now it's time to recap.
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Equipment Review / Re: Transel Transalyzer MarkIII
« on: March 30, 2017, 09:00:35 PM »
Here's a YT video but it's pretty dark
https://www.youtube.com/watch?v=JEf3L2XsPWM
Strange thing, it seems to work now ... all I did was began tracing through the signal with my scope.
Anyway I'm still looking for more documentation if I can find it.
https://www.youtube.com/watch?v=JEf3L2XsPWM
Strange thing, it seems to work now ... all I did was began tracing through the signal with my scope.
Anyway I'm still looking for more documentation if I can find it.
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Equipment Review / Transel Transalyzer MarkIII
« on: March 29, 2017, 12:38:54 AM »
Hey, Buddy,
Jon here. Last weekend I became the proud owner of a Transel Transalyzer MarkIII. I just have to repair a couple tube CB amps in exchange for it. Pretty good trad if you ask me.
Anyway, I hooked it up to a couple different radios and all I get is the watt meter will swing, but the scope just remains a straight line trace. It doesn't seem to be sensing the carrier or modulation at all. I opened it up and had a peek, but without any kind of schematic or service manual, I'm a little bit lost. The only documentation I've found is the instruction manual for the MarkIIIa in the bama archive. Any ideas where to find a schematic or better documentation?
Jon here. Last weekend I became the proud owner of a Transel Transalyzer MarkIII. I just have to repair a couple tube CB amps in exchange for it. Pretty good trad if you ask me.
Anyway, I hooked it up to a couple different radios and all I get is the watt meter will swing, but the scope just remains a straight line trace. It doesn't seem to be sensing the carrier or modulation at all. I opened it up and had a peek, but without any kind of schematic or service manual, I'm a little bit lost. The only documentation I've found is the instruction manual for the MarkIIIa in the bama archive. Any ideas where to find a schematic or better documentation?
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Electronic Video Blog / Re: #107 Email Q&A FT 747 problem - Which scope to get
« on: March 13, 2017, 04:24:41 PM »
I sort of suspected this due ti the age, but wanted a second opinion from someone with experience. Looks like I have some caps to buy. Thanks for the reply.
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Electronic Video Blog / Re: #107 Email Q&A FT 747 problem - Which scope to get
« on: March 13, 2017, 12:18:48 AM »
Speaking of scopes ... I picked up a leader LBO502 a few months ago, and it has a problem. It seems to work OK for 30-45 minutes then the trace goes dim or completely disappears. Then I can turn up the intensity a little and the trace comes back for a while then goes away again. This cycle repeats until the intensity is turned all the way up and the trace goes away for good until I turn it off and let it have a nap.
The filament seems to be OK, and the sweep circuit seems to be ok since I always have a good waveform. So I'm suspecting something in the HV power circuit or the CRT is going. I don't have a HV probe, so how would you suggest attacking this?
73,
Jon
The filament seems to be OK, and the sweep circuit seems to be ok since I always have a good waveform. So I'm suspecting something in the HV power circuit or the CRT is going. I don't have a HV probe, so how would you suggest attacking this?
73,
Jon
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Electronic Video Blog / Re: #90 1965 Fender Deluxe Restoration Tips And Comments Part 2
« on: January 01, 2017, 02:27:44 AM »
I'm going to be building a Fender Champ clone soon. No I don't play, I've just always wanted to build a tube amp.
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Electronic Video Blog / Re: Heathkit IG-1271 trouble shoot and repair video
« on: January 01, 2017, 02:13:06 AM »
Well, I found that R25 and R28 (both 8.2k 1/4 watt) are reading .925K and 1.285k. Tomorrow I'll look and see if I have any 8.2k resistors in my stash and see if that has any effect.
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