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

Sun Oct 19 13:39:57 EDT 2014

Pull one tube and stuff a rag in the hole. Go to 20M and drive with 20-30W 
and use the Tune and Load controls to peak the output at no more than 30ma 
Grid current. Write down the maximum power out.

Swap tubes and do it again.

This will tell you the condition of the tubes and new or very good used will 
do at least 700-750W even with the input and output mismatch as long as the 
exciter doesnt fold back.

Carl
KM1H

----- Original Message ----- 
From: "Prem" <va3uma at gmail.com>
To: "Louis Parascondola" <gudguyham at aol.com>
Cc: <amps at contesting.com>
Sent: Sunday, October 19, 2014 10:49 AM
Subject: Re: [Amps] Fwd: Ten-Tec Titan 425 - input SWR high

> Thanks Louis.
>
> I'll try to get a good-known spare set of tubes.
>
> Note to Gerald: Roger that, sir. The SA test was only for the LPF alone -
> not in situ - just to find out the characteristics of all the elements on
> that board.
>
> I've already told my friend to get hold of a some know-good pulls.
>
> Thanks to all.
>
> 73,
> Prem
> www.qsl.net/va3uma
>
> On Sun, Oct 19, 2014 at 10:31 AM, Louis Parascondola <gudguyham at aol.com>
> wrote:
>
>> 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 at contesting.com>
>> To: va3uma <va3uma at gmail.com>; amps <amps at 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 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,
>> Premwww.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
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>> >>
>> >
>> >
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