Thank you Carl (and all the others too).
For a split second, I wondered why you wanted me to put some rag in the
hole :-)
It quickly occurred to me.... of course, to get the blower air through the
working-tube chimney - and not through the gaping hole. Yes, I'll try that
sir.
73,
Prem
www.qsl.net/va3uma
On Sun, Oct 19, 2014 at 1:39 PM, Carl <km1h@jeremy.qozzy.com> wrote:
> 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@gmail.com>
> To: "Louis Parascondola" <gudguyham@aol.com>
> Cc: <amps@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@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@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,
>>> Premwww.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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