Carl, that was a price quoted by Freeland Products, a tube rebuilder in the
New Orleans LA area. New tubes were around $6K from Richardson Electronics
the last time I checked. There will be no new TH347 tubes in my future!
I have seen pulls for around $200 in Europe but they typically will run a
maximum of 1.2A plate current where a good tube will run 1.9 to 2 A. Even at
1.2A they will output 1500W or more so a pull my be ok depending on what
you are looking for.
A recent batch of four pulls yielded one tube that did 2000W out, one that
did 1500W out, one that did 900W out and one that arced and sparked, not
recoverable.
At this rate, a good pull is worth $400 to $800 depending on how good it
is.
I have, as suggested, considered running the tube with low filament voltage
when off. My operating style may keep me away from 1296MHz for several
weeks at a time so I am not sure I would get a benefit from the low voltage.
Too many bands, not enough time!
73,
Gerald K5GW
In a message dated 8/28/2009 4:53:45 P.M. Central Daylight Time,
km1h@jeremy.mv.com writes:
Gerald, have you considered running the filament black when not in use as
suggested by Siemens?
Is that $2500 in Germany or the USA?
And what is the going price for a decent one in Europe? My #2 son just got
confirmation of his Germany assignment today.
Carl
KM1H
----- Original Message -----
From: <TexasRF@aol.com>
To: <jtml@vla.com>; <amps@contesting.com>
Sent: Friday, August 28, 2009 5:33 PM
Subject: Re: [Amps] TH347 filament ramping
> Fortunately one was used and the other was a rebuilt tube. The filament
> went open like a bad light bulb when they failed.
>
> The price of rebuilt tubes has doubled over the past few years. They were
> around $1200 with a discount coupon now about $2500. While this sounds
> like
> a very high price, the tube is very capable of 3KW plus at 1296 MHz. If
> the
> filament issue is resolved, one can expect a lifetime of use at amateur
> power levels. This makes the $2500 price a bit more acceptable.
>
> So far so good with the relay scheme. That has been in use for a couple
of
> years now.
>
> 73,
> Gerald K5GW
>
>
>
>
> In a message dated 8/28/2009 4:04:14 P.M. Central Daylight Time,
> jtml@losalamos.com writes:
>
> Gerald, that's unfortunate, I hope you didn't pay list price for those
> tubes and have them fail like that.
> Your relay scheme seems like it would have prevented problems. Did the
> filaments burn out or did they just short to grid and stick there?
> 73
> John
> K5PRO
>
>> I lost a couple of good TH347 tubes due excess filament current at turn
> on.
>> I thought there was sufficient turn on current limiting but apparently
>
>> not.
>>
>
> ----
>> 73,
>> Gerald K5GW
>
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