[Amps] Filament transformer for SB-220 needed

[Carl]

A couple of 10 Ohm WW resistors across the secondary will create a virtual 
CT at the center.

That goes back to the 30's and is another possibility Ive used in the past 
when confronted with very cheap non CT iron versus the alternative of 
spending real money.

Carl
KM1H


----- Original Message ----- 
From: "Gary Schafer" <garyschafer at comcast.net>
To: "'Jim Mullen'" <kk1w.jim at gmail.com>; <amps at contesting.com>
Sent: Monday, February 28, 2011 11:24 AM
Subject: Re: [Amps] Filament transformer for SB-220 needed


> If you don't want to buy a new filament transformer you can use a small 6
> volt or 12 volt filament transformer in parallel with the one in the 
> SB220.
> Use the center tap on the small transformer just as you would from the
> original transformer. Only do not connect any leads on the primary side of
> the new transformer to anything. Be sure to insulate those primary leads 
> as
> they will have 50 to 100 volts on them.
>
> 73
> Gary  K4FMX
>
>> -----Original Message-----
>> From: amps-bounces at contesting.com [mailto:amps-bounces at contesting.com]
>> On Behalf Of Jim Mullen
>> Sent: Sunday, February 27, 2011 5:28 PM
>> To: amps at contesting.com
>> Subject: [Amps] Filament transformer for SB-220 needed
>>
>> The subject pretty much says it all. My SB-220's filament transformer
>> decided to quit during the ARRL DXCW contest last week. An odd failure,
>> the
>> center tap of the 5V winding is no longer 'tapped'. I pulled the
>> transformer
>> hoping the connection would be visible after taking off the end bell but
>> no
>> joy.
>>
>> The transformer is in fine shape except for non-tapped CT. Windings look
>> good, no signs of overheating, both primaries and the other secondary
>> are
>> good too.
>>
>> I know Harbach has new ones but if I could scrape up a used one for less
>> $$
>> that would be great.
>>
>> '73...
>>
>> Jim/KK1W
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>
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