Basically yes. 12volts comes up from the 12v supply and feeds the ALO board.
If all is good it sends -2v to the relay. The ALO board interrupts that in a
fault so just bypass it to the relay.
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On Wednesday, November 1, 2023, 6:55 PM, wb0gaz@yahoo.com <wb0gaz@yahoo.com>
wrote:
So remove 12V going into the ALO/Meter board (that came from the xmt/stby
switch), leave the two meters and associated resistors in place (they're
passive), and send the now-removed 12V that went to the ALO/Meter board back to
the relay stuff... Sound right?
On Wednesday, November 1, 2023 at 04:50:42 PM MDT, gudguyham@aol.com
<gudguyham@aol.com> wrote:
The board trip simply cuts out the 12v to the antenna relay board. I just cut
the 12v line and connect it to the line out to the relay. End of story.
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On Wednesday, November 1, 2023, 6:33 PM, wb0gaz@yahoo.com <wb0gaz@yahoo.com>
wrote:
Thanks! That is consistent with my thought - with 3-500Z tubes, there's nothing
to be gained as long as the op pays attention...
If I can identify the PCB-end connectors in use, that will reduce the hassle of
pulling them, but your comment adds fodder to the idea that the board wouldn't
likely be of future use anyway...
On Wednesday, November 1, 2023 at 04:26:44 PM MDT, gudguyham@aol.com
<gudguyham@aol.com> wrote:
Dave, the ALO boards on these amps are for the most part worthless. They
don’t trip on the important factors anyway. When they go bad I usually just
bypass them. Not worth the effort to repair them unless it’s something
obvious. The LK550 HD as 3 3-500 tubes. As long as your meters are working
properly you don’t need any trip circuits. With the LK800 amps the ALO board
has a timer on it to hold off RF until the cathodes warm up, there it’s a must!
But even still I don’t believe it trips on grid overload. If you are
concerned about real protection most tubes benefit from a simple grid trip
circuit which is a lot less complicated than the ALO board. Some ALO boards do
have grid shunt series resistors that will occasionally open up with tube arcs.
They usually can be seen as bad when inspected closely.
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On Wednesday, November 1, 2023, 5:29 PM, wb0gaz via Amps <amps@contesting.com>
wrote:
Thanks (Dave) for insight on the panel meters.
Arriving to the point (on LK550) that the ALO/Meter board is suspect - either
was damaged or caused damage in it's prior life. Several traces handling 12V
path were badly overheated, one to the point of destruction, and the board
(with a couple of previously added jumpers to bypass two of the smoked traces)
is still dragging the 12V DC control power supply (simple half-wave rectified
off the low voltage transformer) down to near zero when amplifier is enabled
(XMIT on the XMIT/STBY switch.)
Now intend to delete ALO/Meter and rewire as if it were a LK500 or other model
without ALO/Meter (hence why I wanted to understand the nature of the two panel
meters.)
Next step is to find pair of nylon 6-pin connectors (equal to what are
currently on the ALO/Meter board); they are physically polarized and a search
through digikey hasn't found anything equivalent so far. Although could remove
the connectors from the (suspect) ALO/Meter board, would rather set it aside
as-is for now and source replacement connectors (on the PCB, the two connector
housing are female, and the (6) pins are male.) My supply of pins doesn't
include any that are the same dimension as the one used on the PCB (else I'd
just stuff equivalent pins into the needed positions on the end-of-wire
connectors and call it a day.)
Thanks again for the hand-holding through this saga!
Dave
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