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

Jim W7RY w7ry at centurytel.net
Sun Oct 19 15:49:58 EDT 2014


Most SWR indicators in modern solid state radios are very accurate. With a 
20 degree index band switch, sometimes the input and output switches can get 
slightly out of sync.

Try to change to the desired band from the other direction. In other words, 
try switch to 40 from 80, or from 20 and repeat your test.

There is a coupling between the tank and the tuned input that may have 
loosed up.

73
Jim W7RY




-----Original Message----- 
From: Gerald Williamson via Amps
Sent: Sunday, October 19, 2014 7:21 AM
To: va3uma at gmail.com ; amps at contesting.com
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 at 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 at gmail.com>
Date: Sun, Oct  19, 2014 at 9:24 AM
Subject: Re: [Amps] Ten-Tec Titan 425 - input SWR  high
To: wl7e at arrl.net


Roger that, Joe. Will let you  know.

73,
Prem.

On Sun, Oct 19, 2014 at 9:12 AM, Joe  <wl7e at 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 at 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 at contesting.com
>>  http://lists.contesting.com/mailman/listinfo/amps
>>
>
>
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