[Amps] Alpha 76 PI-EL modification for WARC bands

[Tom Rauch]

>I would recommend a home made choke wound on a teflon 
>former with a
> length of ferite rod inside. It is quite easy to obtain 
> some 500
> microhenries of inductance with resonance around 700 kHz 
> (really, medium
> wave!). Try some 100 turns 18 AWG on a teflon former of 1" 
> dia. Drill a


I just measured a choke sent to me by some ham that used a 
ferrite or iron core and it was terrible. Came from some KK5 
or K5 design on the web.

It had a ton of inductance, far more than needed, but the 
lowest series resonance was just above 80 meters. On any HF 
frequency the Q was significantly  lower than a regular 
choke. Over much of HF the equivalent impedance was 3000 
ohms or less with hundreds of ohms ESR.

I can't imagine why anyone would want to stick a lossy 
material like ferrite in a choke that has to hold off 
thousands of volts.

73 tom