Hello, Chuck

Put an Ohmmeter between the center pins of the input and output
coax connectors of the amplifier, and check for continuity.
If open, suspect the "back" contacts of the T/R relay need cleaning.
A bit of rubbing alcohol on an index card, pulled
through the contacts while you carefully hold them shut
should clean the contacts. Don't use an emory board
or sandpaper. A burnishing tool is also good, if you can find one.

Also look at the coax jumper cable you use between your rig
and the amplifier. Look for continuity between center pins,
and no short across the coax. (It is easy for a strand
of the coax shield to short out a connector, if the coax braid
wasn't tinned before assembling the PL-259.) Flex the coax
while you are doing the ohmmeter check, to look for
an intermittant short.

73,
Ed Knobloch

Chuck W. KB5GC wrote:

Just picked up a Dentron GLA-1000. Filaments come on in standby, (1100
volts) and the t/r relay seems to be working. However when I put the
amp inline patched with coax between my transceiver and my antenna, I
lose reception as if the receiver can't "see" the antenna anymore.
Even if the amp is turned off. So I won't even try and tune the thing
of course!