Re: Market Value of TWT Amplifier?

From: Bill Janssen (billjNOTTHIS_at_ieee.org)
Date: 11/07/04 

Date: Sun, 07 Nov 2004 16:56:16 GMT

Ed Price wrote:

>
> "Mark & Mary Ann Weiss" <mweissX294@earthlink.net> wrote in message
> news:Iwdjd.7050$Gm6.3327@newsread3.news.atl.earthlink.net...
>
>>
>>>
>>> Before you list it, you need to find out more about it. Does the "LMA"
>>> indicate that it is an "L-Band Microwave Amplifier"? Can you find a
>>> manufacturer's web site or data ***? Have you tested it to verify it
>>
>> meets
>>
>>> specs and hasn't lost its vacuum?
>>>
>>> You may have noticed on E-Bay, that two like items can sell for quite
>>
>> different
>>
>>> prices, depending on how well the sellers present the items. By having
>>
>> good
>>
>>> backup data, and by mentioning Tucker's price for the identical
>>> item, you
>>
>> might
>>
>>> get more than by just describing it the way you did here!
>>>
>>> Fred
>>>
>>
>>
>> It will be quite difficult to list it properly, as I cannot locate the
>> manufacturer on the web. They don't appear to be listed on any search
>> engine. I cannot make direct comparison because no other TWT amp by this
>> manufacturer is selling on Ebay at this time.
>> All I have is a casual statement from the engineer that handed it to
>> me for
>> consignment sale, that it was working the last time he used it. I used
>> Tucker as a reference, though no identical item was listed. I compared
>> against other makes/models having 10W output like this unit, which
>> was the
>> closest match I could find.
>> Perhaps I could list it with a DOA garantee and be ready to accept
>> return
>> and refund in the event that the unit is not up to par. I really hate
>> selling equipment that I don't have the equipment to test (I'm geared
>> for AM
>> & FM commercial transmitter repair, not satellite), but at the same
>> time, I
>> don't want to blow it out for next to nothing. I'd like to protect the
>> interests of the owner, too.
>>
>>
>> --
>> Take care,
>>
>> Mark & Mary Ann Weiss
>
>
>
> Can the amplifier can do 10 watts CW, or is that peak, with a low duty
> cycle? Is it a narrow bandwidth, or a full octave or band model? Does
> it have remote control (like a GPIB port)?
>
> Even knowing these things, a TWT amplifier is a weird item to buy or
> sell. As other posters have noted, TWT's degrade, and their lifetime
> sometimes yields a lousy return on investment. I have had older
> Watkins Johnson 10 watt units that died with just a few 10's of hours
> on them, and I have had some HO 10 watt models that are 30 years old
> and still fine.
>
> I try to "baby" my TWT amps (never overdrive them, always use reverse
> power protection, and always give them a very long cool-down period.
> Is that important? Maybe, maybe not. But might a previous owner been
> as careful?
>
> Anyway, at the least, you should characterize the bandwidth and
> available power for your ad. I would imagine that a very clean, 10
> watt CW L-band TWT amp ought to be worth over $1500; OTOH, if it's
> bandwidth is only a few percent wide, or not continuous rated, then
> worth might be closer to $100.
>
> Ed
> wb6wsn
>
Good advice above, and in addition, if you can find out what it was used
for before it was removed
and why it was removed.. If it was a satellite up link then the band (C
,KU etc.) it was used for
would help. Also is the power supply with the amplifier? The power suppy
may be the most valuable
piece

Good luck
Bill K7NOM

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