Fingers slipped... meant SB-220 instead of SB-200.
( but you alreay knew that ... right ?? )
Don W4DNR
Quoting Glen Zook <gzook@yahoo.com>:
> How are you going to use an SB-200 as a "tube checker"? The 572B
> tubes used in the SB-200 are 4-pin "medium" and the 4-400A and
> 3-500Z tubes use a 5-pin "large"! Then there is problem of the
> filament voltage. The 572B has a 6.3 VAC filament and the 4-400A
> and 3-500Z have a 5.0 VAC filament!
>
> Glen, K9STH
>
>
> Website: http://k9sth.com
>
>
> ________________________________
> From: "donroden@hiwaay.net" <donroden@hiwaay.net>
> To: amps@contesting.com
> Sent: Thursday, December 8, 2011 4:26 PM
> Subject: Re: [Amps] Replacing 3-500Z tubes with 4-400A tubes
>
> 4-400s will work in an SB 200 , but you cant slide it back in its case.
>
> ( tube checker only !!! HV EXPOSED !! )
>
> Don W4DNR
>
>
>
> Quoting Bill Fuqua <wlfuqu00@uky.edu>:
>
>> Well, it does blow some air on the socket but not up thru the socket to the
>> seals.
>> In some 4-400A tubes the pins are connected by smaller conductors from the
>> socket and
>> do not themselves conduct a lot of heat. That is why the sockets and tubes
>> have holes
>> in them and the shields as well. The air is supposed to blow up thru the
>> holes and hit the
>> seals and then out the sides holes in the metal shield.
>> The 3-500z tube do not have the metal shield and the side flow does hit
>> the seals and
>> along with the pin cooling they stay cool enough.
>> You may get by anyway with the 4-400As because they will be running at
>> lower power and
>> they are running in either CW or SSB modes. But if you were running full
>> bore RTTY you
>> may have a problem.
>> The tubes were designed to run with the plates red 24/7 and which is
>> unlikely in
>> a SB220. This is why I was wondering if someone had some real experience.
>> A very interesting seal cooling mechanism is the one that was used in
>> the EIMAC
>> 1000T. The tube was the same size as a 450TH but lots more power. They
>> provided small
>> metal tubes that carried low pressure air straight to the seals on the base
>> and the grid.
>> I guess they were intended to be used as a upgrade for 450T transmitters
>> using same sockets
>> and physical size.
>>
>> 73
>> Bill wa4lav
>> At 04:32 PM 12/6/2011 -0500, Carl wrote:
>>> The SB-220 cools the filament pins.
>>>
>>> Carl
>>> KM1H
>>>
>>>
>>> ----- Original Message -----
>>> From: "Bill Fuqua" <wlfuqu00@uky.edu>
>>> To: "John King" <k5pgw@yahoo.com>; <amps@contesting.com>
>>> Sent: Tuesday, December 06, 2011 9:15 AM
>>> Subject: Re: [Amps] Replacing 3-500Z tubes with 4-400A tubes
>>>
>>>
>>> > One possible issue with the 4-400A is that it has a metal shield around
>>> > the glass seals on the base.
>>> > The cross flow cooling used in some amplifiers does not work well and an
>>> > additional fan
>>> > may be need to cool the seals.
>>> > Maybe someone can comment on this that have had personal experience
>>> > making the conversion.
>>> > 73
>>> > Bill wa4lav
>>> >
>>> >
>>> >
>>> > At 04:20 PM 12/4/2011 -0500, John King wrote:
>>> >>I have several very good 4-400 A tubes and have replaced a pair of bad
>>> >>3-500Z tubes with a pair of 4-400A tubes in a Heath SB 220 amp.
>>> >>
>>> >>I have noticed much lower resting current being drawn when keyed up. I
>>> >>have noticed about 200 watts less power output with 100 watts drive. The
>>> >>4-400A tubes are as new.
>>> >>
>>> >>I made no changes to bias or other parameter adjustment. I would
>>> >>appreciate the benefit of your knowledge and experience
>>> regarding the tube
>>> >>substitution. Thanks and 73, John, K5PGW
>>> >>_______________________________________________
>>> >>Amps mailing list
>>> >>Amps@contesting.com
>>> >>http://lists.contesting.com/mailman/listinfo/amps
>>> >
>>> > _______________________________________________
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>>> >
>>> >
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>>
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>
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