[Moon-net] Advise on bifilar choke for 8877 filament

[Leif Asbrink]

Hi Ed,

> I'm winding coils for my 2m-8877 PA (classic-W6PO design) and am 
> wondering if I might use insulated #12 solid copper wire in place of 
> enameled #12?  I will have to buy a complete spool of the enameled 
> wire mail-order if that is necessary.  It appears to me that 
> insulation in the bifilar choke is for dc voltage so insulation would 
> likely only shift the inductance some.  I can check that with a MFJ-269.
> 
> So what's the opinion on this?
> The remaining coils are all #14 copper which can be found locally.

I do not know the original description, but generally, to feed
the heater of a grounded grid amplifier I would use many enough 
of the enameled wires at hand in parallel and twist the bunch 
of 4, 8 or whatever strands with a drilling machine so they form 
a nice "cable" which can then be used to wind a coil with extremely 
high mutual inductance (and capacitance) between the two resulting 
inductances. Polyimide enamel is non-solderable and low loss :-)

73

Leif / SM5BSZ