On 2013-02-22, at 11:14 AM, Jim Thomson wrote:
>
>
> ## eddy, toss the books. Spend 5 mins with the GM3SEK PI software instead.
> The L PI is the ticket, but it can take many variations. With higher
> amounts of L in the plate lead ( anywhere b4 the tune cap)
> you require less L in the main 10m coil..and vice versa. You can see that
> effect right away in the software. There is NO reason to have to switch
> that coil out of the circuit, why bother ?
Because the tuning on the lower bands was radically altered with it in, far &
away removed from quoted "text book specs" for a pair of 813s in GG...
>
> ## and why would you want to switch the coil in the plate lead at the plate
> caps ? You shoulda just put the coil AFTER the plate block caps, and b4
> the tune cap. Then it wouldn’t have any B+ on your switching contacts.
> The way you have done it, you have both B+ and RF voltage on it. When
> driven full bore, the anode..and your mercury relay contacts...will have
> almost twice the key down B+ voltage on it. The RF in the tank circuit
> is AC. And AC will back feed through the plate block caps... and onto the
> anode..and eveything in its path.
Makes sense---good idea. Guess I shoulda considered that before incorporating
the scheme...as I recall, I simply copied the methodology used in the ARRL
literature...
>
> ## remove your popsicle stick, mercury relay, etc... and toss em. Insert
> your L coil between plate block caps and tune cap. If no room insert in
> plate lead. Toss any parasitic suppressor, the amp doesn’t
> need it on any band.
No---I don't think so. The thing works well enough for me now, as it is...why
fix it, if it ain't broke, right...?! :o)
~73~ de Eddy VE3CUI - VE3XZ
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