>Hi Rich, you mean that if I float the xfmr and bypass everything to the core
>of the xfmr, I assume with .01's, then I put
>a puny bifilar choke in the primary and I don't need ANY choke in the
>secondary?
>Sounds too good to be true.
This is the way commercial amp mfgs do it. For example, a triode with a
7.5v/160a filament is not easy to build a filament choke for unless the
choke goes in the 240v primary of the fil xfmr.
-- I would use a filament xfmr primary choke for a filament of more than
30 amperes (#10-gauge Cu).
> I am planning on locating thefil. xfmr
>down in the power supply area and bringing the 7.5V into the Rf deck thru
>two .2ufd feedthru caps. I also want to keep the CT down in the P.S.
>along with the bias resistor and meter circuitry.
>
Peter Dahl makes custom filament transformers that can be mounted under a
4"
' deep chassis. [photo of 7.5v/75A Dahl xfmr:
http://WWW.VCNET.COM/measures/pb.grid.gif ]
have fun, Bob
>----- Original Message -----
>From: "2" <2@vc.net>
>To: "Bob Maser" <bmaser@tampabay.rr.com>; " AMPS" <amps@contesting.com>
>Sent: Friday, January 03, 2003 8:23 PM
>Subject: Re: [Amps] Filament Choke Inductance
>
>
>
>
>>Can anyone tell me what inductance do I need in the filament choke for a
>>3CX3000A7 for 80M.
>
>The SB-220 uses 9uH. This even works well on 160m if c. 900pF is added
>to C-out in the 160m tuned input pi-network.
>
>>I built one back in the mid 90's and had to wind one
>>around 3
>>ferrite 1/2" rods in order to keep the AC out of the tube(or was it to keep
>>the RF out of the transformer?). I have some filament chokes wound made
>>with 10ga wire and they measure ±45uh. I guess I could always put 2 of
>these
>chokes in
>>series but they would take up more real estate under the chassis.
>>
>To save real estate and greenbacks. float the 3cx3000A7 filament xfmr on
>a G-10 insulating plate, bypass all leads/terminals to the core, and put
>a 3a, bifilar choke in series with the primary.
>
>>...
>
>cheers, Bob
>
>- R. L. Measures, a.k.a. Rich..., 805.386.3734,AG6K,
>www.vcnet.com/measures.
>end
>
>
>
>
>
- R. L. Measures, a.k.a. Rich..., 805.386.3734,AG6K,
www.vcnet.com/measures.
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