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

[Prem]

Thank you Jim. Yes, that is one simple test I missed. After reading your
mail, it does look like a possibility. Last night I had my friend turning
the band-switch as I sprayed De-oxit to the wafer switch in the LPF
compartment, however didn't pay any attention to any slippage. It looked
like it was turning in tandem.
Now that you pointed it out, I'll see if the coupling is OK.

Here's something interesting:
On 2 bands I measured the actual best match (least SWR, R ~50, X~0), and
here's what I found:

Band pos = 40
Best reading = 20

Band pos = 20
Best reading = 15

It looks like the LPF wafer is advanced by 20 Deg (next position ?).
I'll investigate further and keep you all posted.

73,
Prem.
www.qsl.net/va3uma




On Sun, Oct 19, 2014 at 3:49 PM, Jim W7RY <w7ry at centurytel.net> wrote:

> 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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