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

To: TexasRF@aol.com, va3uma@gmail.com, amps@contesting.com
Subject: Re: [Amps] Fwd: Ten-Tec Titan 425 - input SWR high
From: Louis Parascondola via Amps <amps@contesting.com>
Reply-to: Louis Parascondola <gudguyham@aol.com>
Date: Sun, 19 Oct 2014 10:31:12 -0400
List-post: <amps@contesting.com">mailto:amps@contesting.com>
It does not take a "bad tube", it only takes a tube that is low in emission to 
throw off the input match.  Obviously the amp input is designed to be matched 
to tubes that are new.  The amp has plenty of head room and a marginal tube can 
still let the amp make 1500 watts yet "may" present a input imbalance.  NOT to 
be overlooked.  As someone who does extensive amplifier repairs of most tube 
amps, I always have "known" good tubes of all types to substitute into amps to 
eliminate tubes as being the problem.


Prem, if a tube was bad the power output would be much lower than the 1500w 
 you measured.





-----Original Message-----
From: Gerald Williamson via Amps <amps@contesting.com>
To: va3uma <va3uma@gmail.com>; amps <amps@contesting.com>
Sent: Sun, Oct 19, 2014 9:21 am
Subject: Re: [Amps] Fwd:  Ten-Tec Titan 425 - input SWR high


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!
 
72,
Gerald K5GW
 
 
 
In a message dated 10/19/2014 8:37:44 A.M. Central Daylight Time,  
va3uma@gmail.com writes:

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

- 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).

73,
Prem
www.qsl.net/va3uma

---------- Forwarded  message ----------
From: Prem <va3uma@gmail.com>
Date: Sun, Oct  19, 2014 at 9:24 AM
Subject: Re: [Amps] Ten-Tec Titan 425 - input SWR  high
To: wl7e@arrl.net


Roger that, Joe. Will let you  know.

73,
Prem.

On Sun, Oct 19, 2014 at 9:12 AM, Joe  <wl7e@arrl.net> 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  
culprit.
>
> 73,
> Joe WL7E
>
> On Sun, Oct 19,  2014 at 5:02 AM, Prem <va3uma@gmail.com> wrote:
>
>>  Friends, for a long time now, the input SWR on my friend's Ten-Tec  
Titan
>> 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 
to
>> 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 
exciter
>> 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
>> www.qsl.net/va3uma
>>  _______________________________________________
>> Amps mailing  list
>> Amps@contesting.com
>>  http://lists.contesting.com/mailman/listinfo/amps
>>
>
>
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