[Collins] 4D32 question

[jeremy-ca]

Thanks Gerry, thats about what I figured but didnt know if there was a 
particular issue with the seals. Havent had a rig with one since 1960 which 
was a Viking I; just got another last week.
That tube is all over the place lately, even way over priced places like 
Surplus Sales and Gold Co have it down to $20.

Carl
KM1H


----- Original Message ----- 
From: "Dr. Gerald N. Johnson" <geraldj at storm.weather.net>
To: <collins at mailman.qth.net>
Sent: Sunday, August 05, 2007 4:52 PM
Subject: Re: [Collins] 4D32 question


> On Sat, 2007-08-04 at 07:48 -0400, jeremy-ca wrote:
>> I'm wondering if those USAF surplus tubes that have been showing up are 
>> OK.
>> My concern is with gas and vacuum deterioration.
>>
>> Carl
>> KM1H
>>
>>
> The only thing would be to first cook them with filament/heater power
> alone for a day or two or longer. Then build a gas checker and see if
> the gas is low enough to be usable. Lots of leads to be sealed could
> mean that the getter can't clear up the gas. A fading getter deposit
> would hint its all used up. And warming the getter deposit by some heat
> more than the heater may speed up its action.
>
> Its unlikely the seller has done any of these things to the tubes so it
> wouldn't be smart to pay much for them.
> -- 
> 73, Jerry, K0CQ, Technical Advisor to the CRA
> All content copyright Dr. Gerald N. Johnson, electrical engineer
>
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