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Re: [Amps] Fwd: Ten-Tec Titan 425 - input SWR high

Subject: Re: [Amps] Fwd: Ten-Tec Titan 425 - input SWR high
From: Gerald Williamson via Amps <>
Date: Sun, 19 Oct 2014 10:21:27 -0400
List-post: <">>
Prem, if a tube was bad the power output would be much lower than the 1500w 
 you measured.
The spectrum analyzer does not have enough drive power, same as the MFJ  
Analyzer, to test input vswr.
The unchanged plate tune and load settings suggest the amplifier is working 
 properly as well.
Happy hunting!
Gerald K5GW
In a message dated 10/19/2014 8:37:44 A.M. Central Daylight Time, writes:

Good  morning gentlemen, and thanks to all for the quick and concise  

- One of the tubes being bad: Will see if spares are  available
- LPF caps going bad: My plan was to analyze the cut-off freq for  each band
(@ Z=50R) on my Spec-analyzer/tracking-gen - but left this option  to the
last, and also wanted to hear of other 'easy' methods from the gurus  who've
already worked on this Amp.
- Plate/Load settings: The actual  numbers match the ones in the manual
(surprisingly - even after all these  years).


---------- Forwarded  message ----------
From: Prem <>
Date: Sun, Oct  19, 2014 at 9:24 AM
Subject: Re: [Amps] Ten-Tec Titan 425 - input SWR  high

Roger that, Joe. Will let you  know.


On Sun, Oct 19, 2014 at 9:12 AM, Joe  <> wrote:

> Prem,
> I would be  interested in what you find out. I am having the same trouble.
> I am  now replacing the tubes in my Alpha as that seems to be the  
> 73,
> Joe WL7E
> On Sun, Oct 19,  2014 at 5:02 AM, Prem <> wrote:
>>  Friends, for a long time now, the input SWR on my friend's Ten-Tec  
>> 425 is very high (average > 2 on all bands) - when  measured with a MFJ
>> analyzer at the input - with a 50R dummy-load  at the AMP output.
>> So long, he's used an ATU between  the exciter and the 425, but I'd like 
>> find out if there's way  to fix this SWR problem (no slug-tuning. fixed L
>> and C in the i/p  LPF).
>> I've already checked/assessed the  following:
>> 1- Amp gives full o/p of 1500W pep on a DL with an ATU  between the 
>> and the amp (so, tubes should be OK  ?)
>> 2 - The vacuum relay contacts test 100% OK with a multi-meter  continuity
>> test.
>> 3 - No visual or smell indication of  any burns/arcing/toast - in the I/P
>> LPF or in any other circuit  elements.
>> 4 - Band switch contacts look good. Cleaned with De-Oxit  - just to be on
>> the safer side.
>> 5 - Ig and Ip are as  per specs
>> Any help/lead is  appreciated.
>> 73,
>> Prem
>>  VA3UMA
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