Topband: amp tripping on 160

[Ian Fugler]

I'm afraid that I as soon as I saw the email header I guessed there would be mention of an Expert amp.  If you have the opportunity to borrow a more reliable amp and try that, I would be interested in your results, please.

73, Ian G4iiY



-----Original Message-----
From: Topband [mailto:topband-bounces+zen90387=zen.co.uk at contesting.com] On Behalf Of Jose_Carlos
Sent: 29 October 2021 16:17
To: WW3S; FZ Bruce
Cc: topband at contesting.com
Subject: Re: Topband: amp tripping on 160

My old friend  N8PR(SK) had a similar problem. Peter QTH was few miles for a AM station. The SPE amp is very sensitive, the signal from the AM station was strong enough to trip the amp. The solution was a 2 KW high pass filter to attenuate 30 db the signal from the AM station. Keep attenuation only as necessary to avoid the amp to trip and keep insertion loss very low.. You can use few  10W 10db  attenuator to figure out now much attenuation you need. If it is external signal coming in, you don’t need to transmit, the amp will trip just actuating the PTT.

73’s
JC
N4IS

Sent from Mail for Windows

From: WW3S
Sent: Friday, October 29, 2021 11:06 AM
To: FZ Bruce
Cc: topband at contesting.com
Subject: Re: Topband: amp tripping on 160

I have toroids on all the cables….and even started pulling cables out of the shack to see if it made a difference….im beginning to wonder if the amp has a fault….

Sent from my iPad

> On Oct 29, 2021, at 10:57 AM, FZ Bruce <k1fz at twc.com> wrote:
> 
> It is likely RF traveling into the amp via multiple wires, cables. Recommend you put RFI cores on the coax between the radio and amp, and on the antenna coax near the amp. 
> 
> ( also possible getting on power supply connections)
> 
> 73
> Bruce-K1FZ
> 
> -----------------------------------------
> 
> From: "WW3S" 
> To: "topband at contesting.com"
> Cc: 
> Sent: Friday October 29 2021 10:44:39AM
> Subject: Topband: amp tripping on 160
> 
> After two great nights of being able to receive, I am beyond frustrated,
> as I cannot transmit....something happened recently, and I cannot figure
> it out... I suspect its RFI, but not sure why.....as soon as I transmit
> on my Inverted L, my SPE 1.3KFA amp trips, saying SWRT exceeds
> limits.....yet the SWR displayed is 1.46 to 1.....new to me, but not
> new to this season is my tower which holds my Inverted L.....it was 50'
> of Rohn 25, with a Hazer, its now a Alumnatower 48', with a
> wonderpole.......but.....that setup did work, as I worked S9OK and
> 3DA0RU with it....I added a second receiving loop in the front yard, so
> thought that was it, but I took those cables out from the shack and
> still have a problem....yesterday morning, I found the short piece of
> coax had a nick in it, from the mower I guess, so replaced it, and
> shortened my L a bit to bring the SWR a bit further up the band.....I
> tested yesterday morning and it was great, low , mid and high power,
> even 1300 watts of RTTY, no failure, I tried several times during the
> day and all was great until darkness, and as soon as I keyed the amp,
> failure.....I pulled out what little I have left of my hair trying to
> figure this out......the wonderpole is grounded and I "assume" the tower
> is grounded thru that......should I separately ground the tower? Doing
> so will complicate tilting it over, plus I only have copper grounding
> attachments, I thought I read where I shouldn't use dissimilar
> metals.....but willing to try anything to get my 160 TX ability
> back...thoughts?
> _________________
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