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Post by 2600 on Feb 17, 2023 1:08:21 GMT -5
This radio uses a relay to transfer circuits between receive mode and transmit.
Does it go "click"? Can you see the lever inside the relay move when you key the mike?
Is the 345 Volt reading on V601 pin 6 while receiving, or while the mike is keyed?
Next place I would look are V601 pin 3. Should be around 105 Volts receive, around 55 Volts transmit. This one is important. If it's too low, the relay will never energize.
V601 pin 7 is where the mike socket's transmit pin is wired. This should drop to zero when you key the mike.
73
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389
Mudduck
Posts: 39 
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Post by 389 on Feb 17, 2023 1:30:20 GMT -5
Yes relay is operating, and it is a brand new one from Greg. Also put a rebuilt Bal mod board in , that was working great in my other d201a.
V601 Pin 6 shows 341v on RX and 326v on TX. Pin 3 has 32v rx and 31v TX.
V600 (you mention v601, but did you mean v600 ?) pin 3 is 370v
rx and 52v tx. pin 6 is also the same area as 3 in voltages for tx/rx. Pin 7 has 12.6v rx and 0v tx (as you said grounding the relay tube).
So there voltages are not as expected.
I have replaced R626, R625, R624, R646, R635, R3 & R4, C8 and C610.
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389
Mudduck
Posts: 39
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Post by 389 on Feb 17, 2023 3:09:09 GMT -5
Update, I now have modulation, ssb and am , I thought 'heck lets replace these 6GH8A audio/relay tubes again' re; recently previously replaced v600.601.601 n audio board I got from gobble75 on ebay, now today with some new K5SVC tubes, and now modulation am and ssb. The mod led dances along as expected on am. However still very little power. Showing 1 w on meter on ssb voice peaks, so making progress but need to get the power back  So cannot always trust trhe tubes these guys sell. *** Update, at the finish line T700 was way off, and now, a 3 watt carrier and good 12w swing 15w pep at least on ssb. I think we are good. Will test and see, Thankyou Chris., Always appreciate your input. Looking forward to fitting your AA board base plug kit to the other d201a here that has occasional whiny sessions. New BA board and everything else so I am suspecting the AA connections. |
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Post by 2600 on Feb 18, 2023 23:47:25 GMT -5
Way cool! Good to hear you got a result. Congrats for sticking with it.
73
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So cannot always trust trhe tubes these guys sell.