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JD
I think Andrew suggested that capacitors may be the issue. There are
two
large smt capacitors in the filter section after the PA section. I
removed
these and measured them. The result is as follows:
C327 = 942 nF
C972 = 811 nF

These are rated at 680 nF and measure 20 to 30% high in value.

I will check other caps in the path before the driver.

Any thoughts?

Tommy




On Wed, Jan 29, 2025 at 1:02?PM J.D. Barron via groups.io
<jeter.d.barron=
[email protected]> wrote:

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 groups.io

<jeter.d.barron=

[email protected]> wrote:

Take a good look at RL801

On Wed, Jan 29, 2025, 11:06?AM Tommy Wooten via groups.io <kf4rwg=
[email protected]> wrote:

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 groups.io
<jeter.d.barron@...> wrote:

(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)

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

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).

I would verify that the VR14 voltage is present first and then -

if

present

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.

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).

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.

Just my best guess without making some measurements, but this is

where

I would start.

Good luck and best regards.

JD
KE4MD