RL801 may not be making good contact. You can check the levels with your scope. I would use SSB and whistle in the Mike for tracing to keep the power dissipation low.
On Wed, Jan 29, 2025, 11:51?AM J.D. Barron via <jeter.d.barron=
[email protected]> wrote:
Take a good look at RL801
JD
I was able to access each of the relay leads from the top side of the PA board.? I found that each relay had the 14VR supplied at the relay coil.? The voltage is 10.5V and falls to 9.2V when tx is activated.? I verified that L1 thru L7 leads were 10.5V and dropped to 130mV (gnd) when activated by the appropriate band selection.? PHT8 at RL801 acted same when tx is activated.
All gnd readings were 130mV except RL941 read 363mV as an observation.
All relays seem to click appropriately when each band was selected.
I cannot access IC981 since it is on the bottom side of PA.? But from the info above it indicates it is working correctly.
This does not explain why I was able to see 6W at the output of L305 but I see negligible power when it passes through the filters.? There must be a short or open in path.
No smoking gun yet!
I won’t stop until I find the issue or tear something up.
Thanks
Tommy?
On Tue, Jan 28, 2025 at 5:45?PM J.D. Barron via <jeter.d.barron=
[email protected]> wrote:
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(PA 1) The RF comes from L305? through HF03 to RL-801 (PA 2) (changes from orange to blue and out through (A). to?
(PA 3) the bandpass filters. There are a pair of relays that have to be energized for each frequency band. The input relays are controlled by L1 - L7 (Bus line 3) from the (PA 3) Q980 - Q987 by the outputs from IC981. (Powered by 3R3V)
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14 VR provides the operating voltage for these relays and the output relays. (At this point I have to say I have not looked long enough and hard enough to understand how the output relays are activated but they must be.) as each band is selected by L1 - L7 going low.
VR14 comes from RL701 output through L981 and resistors R1002 (150 ohm) and 1003 (180 ohm) (paralleled). This line also provides power to RL801 which would also stop the RF power from getting to the bandpass filters HF03 (Orange) to A (Blue). If R1002 and R1003 were open this would cause this problem as well. One of the anti-flyback diodes shorted could take out these resistors
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I think that as each L1 - L7 goes low that low is transferred via the blue line to the normally closed contact on the relay below to ground on the unenergized relay (I think).
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I would verify that the VR14 voltage is present first and then - if present
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I would look for the L1 - L7 signals being pulled low by Q980 - Q987. end then If switching I would look to?
The outputs on IC981.
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I believe you will find the problem in this area as you are drawing current indicating power being produced (unless the current is not in the 1-3 Amp range in SSB no modulation idling current).
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Since the power is not going through L961 the FOR / REV (SWR) transformer and being read by IC060 (JFOR) the RF drive is going to the point of current limit and cannot be adjusted in any carrier mode with the power adjustment.
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Just my best guess without making some measurements, but this is where I would start.
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Good luck and best regards.
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?JD
KE4MD
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