[AMRadio] Pi-Net vs Link Couple


W5OMR/Geoff w5omr at satx.rr.com
Thu Sep 22 20:13:04 EDT 2005


Byron Lichtenwalner wrote:

> Geoff
>
> Don't have the tube characteristics here, but from your description 
> your changing the operating point of the amp by changing L/C ration.  
> Or the "transformer effect"  (turns ratio of link to plate coil) gives 
> a better match to the antenna)
>
> If you have a 1000 pf that will take the voltage, start there.  If you 
> loading to an untuned link,  I bet you can load that thing like your 
> using a bucket of bricks. 


That's the idea, Byron - to use a capacitor in series with the output of 
the link to the load (antenna).

I my case, it's a relativly short run (10 ~ 15' of RG-8) to the input of 
a Heathkit 2060, which the open wire line output feeds 450 ohm ladder 
line, that feeds a full-wave delta loop on 75m.

With the capacitor in series (someone else suggested an air variable 
broadcast tuning cap out of an old receiver) I can tune the link to load 
the final a bit heavier.

1000pF would probably be a good place to start.

Thanks!

--
73 = Best Regards,
-Geoff/W5OMR






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