Evan brought up a good point. MY information was regarding an
unmodified L-4B. Quite likely an open diode.
But there are a lot of amps that have been modified to work with the
wimpy relay or transistor VOX switches in newer rigs.
And I doubt you'd be the first guy to bump the ALC knob in and not
notice it until AFTER you posted a note asking for help!
73, Garey - K4OAH
Glen Allen, VA
John Hudson wrote:
Guys come on, notice I've been operating the amp for a while with multiple
rigs.. Clearly that's not the problem, I'm suspecting a diode.. But we'll see.
De WA6HYQ
-----Original Message-----
From: [email protected] [mailto:[email protected]] On
Behalf Of Garey Barrell
Sent: Wednesday, August 18, 2010 12:00 PM
To: [email protected]
Subject: Re: [Drakelist] L4B KEYING CIRCUIT FAILURE
Evan -
Good point! I assume too much....
73, Garey - K4OAH
Glen Allen, VA
K9sqg wrote:
John,
For the VOX connector/circuit to work, the ALC pot switch must be in
the out position.
-----Original Message-----
From: John Hudson<[email protected]>
To: [email protected]<[email protected]>
Sent: Wed, Aug 18, 2010 2:26 pm
Subject: [Drakelist] L4B KEYING CIRCUIT FAILURE
A simple question (as if there really are any) about the Keying
circuit of an L4B. Because I use several radios to drive the L4B I
have a relay connected to the amplifier keying circuit that really
only grounds the leads, that has now failed to work. I looked at the
schematic and it appears there could be voltage on the VOX pins and
it’s actually referenced in the manual that if you have the pins
reversed the plate current will go up and to reverse the pins. There
is no voltage present!
· Saying all that, what voltage should I see if any on the keying
circuit when not keyed?
· Has anyone experienced this before and if so what did you find?
Yes, before anyone says it, I know ultimately I have pull the unit out
of line and take it apart to trouble shoot but I also know symptoms
can provide a path to repair and a place to start.
Thank you (in advance),
John N. Hudson III, WA6HYQ
“C” line, TR4C, RV4C, L4B, MN-2000, TR-6 Owner-Operator.
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