Re: Topband: Heater Choke Value

["ZR" <zr@jeremy.mv.com>]

Typical reactance rule of thumb is 5 to 10X the input impedance of the 
tube(s).
In some cases it is much less and the 160M input network is modified to 
compensate.
#18 or 20  enamel wire would be suitable for 4A and be a lot easier to wind 
than 12 and require a lot less ferrite.
Carl
KM1H


> Mike(W5UC) & Kathy (K5MWH)
> Sent: Wednesday, January 09, 2013 4:37 PM
> To: topband@contesting.com
> Subject: Topband: Heater Choke Value
>
> Hello Fellow Topbanders:
>
> I have just started the process of converting a MLA-2500 amplifier from 
> it's
> original 8875 tubes to Gi-7b tubes.  Current;y I can run only abut
> 400 watts on Topband, (not from the MLA=2500,  I have no tubes for it) The
> conversion requires a RF Choke in the filament lines.  I have searched the
> Handbook, and looked at several schematics with no luck.
>
> Please, can someone out there advise the value of reactance required for
> this effort.  Most construction articles recommend #12 wire, which in this
> case, appears to be significant over kill, as the heater current is only 4
> amps total.
>
> Thanks & 73,
> Mike, W5UC
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Topband Reflector