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Test Equipment / Re: Marconi
« Last post by Paulsbox on July 02, 2018, 11:02:10 PM »
Failing all test 1ís
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This is a video by Alan w2aew on the Tektronix 465B trigger controls

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Test Equipment / Re: Marconi
« Last post by Radio Tech on June 30, 2018, 08:32:35 AM »
I cannot recommend anyone that works on these at a fair price.
But what selftest is it failing?
Sometimes pulling boards and cleaning the connectors will fix the problem.
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Test Equipment / Marconi
« Last post by Paulsbox on June 28, 2018, 06:02:41 PM »
I have a Marconi 2955, cosmetics not that good, fails some self test. Anybody work on these reasonably?
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Ham Radio Circuits and Repair / Kenwood TS-140S Power Down
« Last post by Electrofrying on June 21, 2018, 02:53:33 PM »

Does anybody have any tips to diagnose a apparently dead Kenwood TS-140S?
This is a newly acquired radio that checked out when i bought it. Send and receive was working, I made contact on the noontime net on the 40M band at the time I picked it up.
I took it home and  I was attempting to make phone contact on the 10M band to a local known contact who i was also on the telephone with.
I was transmitting at 10W with reflected power reading between 0 and 1:1 on my MFJ949D tuner's meter
He said he could hear me key but no voice modulation.
I saw that my MIC GAIN was at MIN so I turned it up to 50% and as soon as I pressed the mic key the unit powered down and is apparently dead now, will not power up at all.
There were no bad smells or sounds.
I tried the reset sequence with no success.

I have experience with tube audio circuits but not much RF anything.
Does anybody have any suggestions where to start with this?
I have some test gear, meters. power supplies, scope, signal generator, etc and I have the service manual but could use some guidance.

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Test Equipment / Old equipment info needed -wartime signal generator?
« Last post by Johntweety on June 20, 2018, 11:26:58 PM »
I am working on getting info on a piece of test equipment to rescue it from the junkyard.
It has a metal radio box with coil speaker in the back. It powers up but has no tubes because they were valuable, probably a rectifier and four 6v6ís. I donít know model or schematics but I can see the power  and output trans label. Wiring looks good and factory with old caps. Any info would be great, thanks. JR
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New member welcome / Re: Hi From North Carolina
« Last post by Radio Tech on June 19, 2018, 05:06:15 AM »
Hi and welcome to the forum.
I am in North Carolina. I see you are in North Wilkesboro, not that far away.
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Ham Radio Circuits and Repair / Yaesu FT-920 has two issues
« Last post by ke4cij on June 18, 2018, 10:03:04 PM »
I recently traded for the Yaesu FT-920 pretty much figured it would have issues as some older rigs do. The Rig came from an outstanding ham, he has taken excellent care of the rig and appearance it's a 9 out of 10. That said it does come to me with 2 problems that are basically well over my pay grade.

1. the auto tuner is flaky, it does come on and tries to tune but doesn't tune down the swr well on an antenna or band that's well about 2 on desired frequency before being tuned. Best the thing well do is rattle a few seconds and pretty much settle on an SWR that's higher than it was when it started. It does the same thing on a dummy load...

2. This is annoying more than anything but it leads me to suspect this could lead to troubles down the road. When Keying the Mike and speaking, it feeds back into the speaker. NO THE STATION MONITOR IS TURNED OFF before someone suggests it's on. It's off, I repeat it's OFF. You can hear very clear difference when the monitor is on. It's clear and can be controlled by its controls.

It feeds back through the internal speaker but isn't nearly as noticeable on the internal speaker.  It feeds back on the head headphones. It also feeds back to an external speaker which is the SP-8. Someone suggested it was the mike, well I have changed the microphone to 4 different mikes, next it was the external speaker cable but yea I Changed it for giggles and nope it didn't solve the problem. Also suggested a grounding issue, well the rig does it grounded or not. So I suspect it's something internal. The feedback sounds like the montior is on but a very low volume and has some static present in the audio and it is some what distroted. It's low but loud enough to drive one batty!

That's where I am not sure what to check or where to check! Advice?

Any advice would be greatly appreciated and I know when something is over my head and will not cause damages. That said, I thought it might be something simple some of you guys had seen before, maybe a loose cable, a bad cap, diode or something simple that would be an easy fix before I send this rig out for repair. I can live with the auto tuner problem as I normally use a manual tuner when needed. But this speaker thing is annoying as the day is long!


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New member welcome / Hi From North Carolina
« Last post by ke4cij on June 18, 2018, 09:32:58 PM »
Hello everyone and hello from North Carolina. Been Watching The Radio Shop, love those repair videos! Just wanted to meet the guys who do the excellent work!
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Test Equipment / Re: RCA Senior Voltohmyst
« Last post by Radio Tech on June 17, 2018, 08:24:50 AM »
Hi Mark and Welcome.
If you want an original they show up on ebay at times.  The good thing is it is a simple design probe.  1 meg ohm resistor and a switch. I have built many of these using large sharpie pens.  Remove the end and pull the ink tube out.  I have also used pvc tubing as well.  Sometimes we have to get very creative.
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