[Amps] Fil transformer

[MU 4CX250B]

Kelly, I'm afraid I don't understand your comment. When I look at the
schematic of the Clipperton L, it appears the RF is fed symmetrically
to each side of the filaments, through .01 µF caps.

On the other hand, the DC operating bias is inserted on one side of
the filament transformer secondary, so perhaps that is what you are
referring to. I agree that, ideally, it would be best to feed the bias
through a center tap on the filament. transformer. However, it seems
pretty complicated to add another transformer just to balance the bias
insertion point. I'm wondering if a bit of extra filtering, or perhaps
inserting the bias on the downstream side of the filament chokes would
be an easier solution.
73,
Jim w8zr

Sent from my iPhone

> On Aug 10, 2017, at 9:50 AM, Kelly Taylor <ve4xt at me.com> wrote:
>
> Hi Russ,
>
> Thanks. Just to be clear, I do not require a transformer for providing filament power: it's to fix a design flaw in the Clipperton L, which lacks a centre tap for the filament windings and instead feeds the filaments with RF on one side only, introducing hum.
>
> The fix is to parallel a centre-tapped 6v transformer secondary with the filament windings on the main transformer and move the RF input to the new centre tap.
>
> The Hammond 166j6 is ideal, as it can be added with no metalwork, and you simply cut off and tape the primary windings.
>
>
>
> 73, kelly, ve4xt,
>
>
> Sent from my iPhone
>
>> On Aug 10, 2017, at 11:33, Radio WC6W <wc6w_amps at yahoo.com> wrote:
>>
>> Hi Kelly,
>>   I have a Stancor P-6134 that should do for that.
>>
>>   http://qsl.net/wc6w/wc6wfsw/index.html?fr36.html
>>
>>   Though shipping to Canada may be a dealbreaker.
>>
>> 73 & Good morning,
>>  Marv WC6W 310 649 3111
>>
>>
>>
>> --------------------------------------------
>> On Wed, 8/9/17, Kelly Taylor <ve4xt at me.com> wrote:
>>
>> Subject: [Amps] Fil transformer
>> To: amps at contesting.com
>> Date: Wednesday, August 9, 2017, 11:35 AM
>>
>> Hi all,
>>
>> Seeking a six-volt filament
>> transformer. Must be centre-tapped. To fix the AC hum
>> problem on my Clipperton L.
>>
>> Must be about the size of a Hammond
>> 166j6, about 3 inches wide (to fit without metalwork).
>>
>> If you have something, let me know. If
>> I can't find what I need used, will just buy new from
>> Mouser.
>>
>> 73, kelly, ve4xt
>>
>> Sent from my iPhone
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