a different antenna, like I think you said a 40m V, might not reflect harmonics
as well as the traps on a yagi would.
Aug 27, 2015 10:02:03 AM, kzerohb@gmail.com wrote:
Don't have a second amp, but the amp plays just fine on a different antenna.
__73, de Hans, K0HB
"Just a Boy and His Radio"™
On Thu, Aug 27, 2015 at 8:51 AM, john@kk9a.com wrote:
> Trying a different amp could rule it out.
> John KK9A
> To: "'Ham - Tower Talk'"
> Subject: Re: [TowerTalk] TH7-DX 15M problem
> From: "David Robbins"
> 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
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