Trying a different amp could rule it out.
John KK9A
To: "'Ham - Tower Talk'" <towertalk@contesting.com>
Subject: Re: [TowerTalk] TH7-DX 15M problem
From: "David Robbins" <k1ttt@arrl.net>
Date: Thu, 27 Aug 2015 11:19:54 +0000
No, running the amp into a dummy load won't rule out the amp. A high swr
like
that caused by the amp is because the amp starts detuning and generates
harmonics, it?s the harmonics that would be reflected causing the high
reverse
power. Running into a dummy load would likely not show that unless there
were
a good lowpass filter in between to reject them.
David Robbins K1TTT
-----Original Message-----
From: TowerTalk [mailto:towertalk-bounces@contesting.com] On Behalf Of Robert
Harmon
Sent: Wednesday, August 26, 2015 21:32
To: Ham - Tower Talk
Subject: Re: [TowerTalk] TH7-DX 15M problem
Hans,
I would have suspected the 15 meter traps too.
I would start doing the process of elimination to narrow down the culprit.
Disconnect the coax feeding the TH7 in the shack and put a coax jumper to a
dummy load and run the amp full bore on 15 and see if the SWR stays ok.
I know you think the amp is OK, but this will rule it out.
Then reconnect the TH7 coax and go up to the TH7 and disconnect the coax from
the TH7 connection terminals. Connect the coax to the dummy load again.
Back to the shack, load it up on 15 again and see what happens. If you still
have the swr anomoly, then you have ruled out the amp and the feedline.
It is in the antenna.
I had a similar problem with a KLM KT34XA one time and went thru this, then
lowered the antenna down to sawhorses in the back yard and cleaned, and
reconnected every element connection point and found a connection to one
of the
linear loading tubes that was squirrely. Put the antenna back up and all was
good.
Bob
K6UJ
_______________________________________________
_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk
|