[ARC5] Fw: Varying oscillator frequency. re: Anode voltage on tank coils ...

[WA5CAB at cs.com]

Henry,

Yes, both the oscillator and the PA tank coils in all three Command Set 
transmitter variants have powdered iron cores for tracking adjustments.  And 
yes, the permeability of iron cores varys with flux density.  How much in this 
case I couldn't say.  But the DC flowing in the oscillator coil is the 1626 
filament current (mainly) which shouldn't vary much.  

I've always assumed that the reason for the shift from series to shunt feed 
in the ARC-5 PA was to reduce the peak voltage on the tuning and padder 
capacitors.  Maybe to raise the safe operating altitude or something like that.

In a message dated 4/17/2011 7:26:17 AM Central Daylight Time, 
meils at get2net.dk writes: 
> I wasn't referring to inductors having metal (metallic) cores
> BUT don't the Command set transmitter oscillators use a
> powdered ferrite adjustment core? Shouldn't a DC current
> influence the core mU and thus coil inductance? Though assumedly
> not even approach saturation under normal transmitter operating 
> conditions.
> (As far as I can see, Magnetrons/Klystrons operate on entirely
> different principles so I suppose my comparison was irrelevant.)
> 
> Henry
> 
> 
> 
> ----- Original Message ----- 
> From: "Henry Mei'l's" <meils at get2net.dk>
> To: <arc5 at mailman.qth.net>
> Sent: Sunday, April 17, 2011 12:08 PM
> Subject: Varying oscillator frequency. re: Anode voltage on tank coils in 
> the GF-11 and SCR-274N series Command transmitters
> 
> 
> >Pretty sure I've read that DC coil current flow is actually used to vary 
> >oscillator frequency.
> >I don't know if this is remotely relevant to klystron and/or magnetron 
> >burst pulse operation.
> >Back to the theory books for me or maybe some internet research unless 
> >someone like
> >Dennis, John, Ken, Les, and many more here .... can fill me.
> >(BTW if any are tired of my "witty comments" - what about me: I have to 
> >hear them
> >everywhere I go!  Maybe Mark Twain somehow sneaked into my family tree.)
> >
> >Henry
> >oz3o (oz1uf)  n2nr
> 

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