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Re: [Amps] SB220 tune capacitor

To: "'Joe Subich, W4TV'" <lists@subich.com>
Subject: Re: [Amps] SB220 tune capacitor
From: "Martin Sole" <hs0zed@csloxinfo.com>
Date: Tue, 19 Oct 2010 12:48:33 +0700
List-post: <amps@contesting.com">mailto:amps@contesting.com>
Thanks again Joe,

Very informative , though I swear my archive searches fail to turn up such
nuggets, must be my search terms hi hi! The original part is a 26-131, says
so on it, and I'm confident that the replacement is a 26-164. Given the
improved voltage rating and relatively easy replacement it seems I'm in luck
so far. Have located SB-221-2 bulletin which details the change and parts so
looks like I will be good to go with the new part when the time comes.

Martin, HS0ZED


-----Original Message-----
From: Joe Subich, W4TV [mailto:lists@subich.com] 
Sent: 19 October 2010 12:22
To: Martin Sole
Cc: amps@contesting.com
Subject: Re: [Amps] SB220 tune capacitor


Martin,

 > I might be looking for the special end plate then, or at least some  >
pictures to see if I can fabricate one.

I had to do some review but now that I looked at some SB-220 pictures, it
seems that what they did was use a threaded stand off between the tuning
capacitor end of the 10 meter coil and the lug on the end of the coil.  The
coil remained in position but a 1.5" or so aluminum stand off filled the
space to the plate.

Here is a link to the archives of "Amps" that describes the change:
http://lists.contesting.com/archives//html/Amps/2006-06/msg00118.html

 From memory the stand-off "DA" was either 6-32 or 8-32 (which ever matched
the screw holding the 10 meter coil to the bracket with the blocking
capacitor) x 1.5."

73,

    ... Joe, W4TV


On 10/18/2010 10:43 PM, Martin Sole wrote:
> Thanks Joe,
>
> I might be looking for the special end plate then, or at least some 
> pictures to see if I can fabricate one.
>
> 73
> Martin, HS00ZED
>
>
> -----Original Message-----
> From: Joe Subich, W4TV [mailto:lists@subich.com]
> Sent: 19 October 2010 09:22
> To: amps@contesting.com; hs0zed@csloxinfo.com>>  Martin Sole
> Subject: Re: [Amps] SB220 tune capacitor
>
>
>   >  Did the tune capacitor change during the life of the SB220 or>  
> perhaps with similar amplifiers? SB200 HL220 etc.
>
> Yes, later SB220 had a higher voltage breakdown (wider space, more 
> plates) capacitor that was longer.  It generally came with a special 
> end bracket for mounting the 10 meter coil.
>
> 73,
>
>      ... Joe, W4TV
>
> On 10/18/2010 10:07 PM, Martin Sole wrote:
>> Perhaps a question for the Heathkit history buffs.
>>
>>
>>
>> Did the tune capacitor change during the life of the SB220 or perhaps 
>> with similar amplifiers? SB200 HL220 etc.
>>
>>
>>
>> I have received a replacement capacitor, well it's in UK awaiting 
>> onward shipment. From a picture of the actual part sent to me it 
>> appears to have two differences with the original part, these being 
>> that the ceramic insulators are mounted outboard of the aluminium end 
>> plates whereas on the original they are inboard and secondly that the 
>> number of fixed / moving vanes is 21/22 as opposed to 18/19 on the 
>> original part. I am awaiting confirmation of mounting hole spacing 
>> which might be the most significant issue, assuming the min C is not 
>> now
> too high.
>>
>>
>>
>> Any thoughts?
>>
>>
>>
>>
>>
>> Thanks
>>
>> Martin, HS0ZED
>>
>>
>>
>>
>>
>>
>>
>>
>>
>> _______________________________________________
>> Amps mailing list
>> Amps@contesting.com
>> http://lists.contesting.com/mailman/listinfo/amps
>>
>
>

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