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

[Prem]

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
> >>  _______________________________________________
> >> Amps mailing  list
> >> Amps at contesting.com
> >>  http://lists.contesting.com/mailman/listinfo/amps
> >>
> >
> >
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