[AMRadio] Re: Need list of good AM radios to start lookingfor.


John Lawson jpl15 at panix.com
Wed Nov 16 21:01:38 EST 2005



On Wed, 16 Nov 2005, ne1s wrote:

> On the Ranger accessory plug are available LV B+ (~300V), HV B+, and each 
> secondary lead from the mod tranny. You can simply rewire a new plug to hook 
> the "bottom" of the mod xfmr secondary to LV B+, or, you can do as I did: 
> mount the plug in an aluminum minibox along with a SPDT switch rated for the 
> voltages involved to switch the bottom of the mod xfmr secondary between LVB+ 
> and HV B+. The entire minibox assembly splugs into the acessory plug on the 
> back of the Ranger. Make sure you ground the minibox to the ground pin on the 
> accessory plug, for safety's sake. 
> Works FB, got the idea of using the LV B+ from Timtron. 
> Ranger puts out ~12-15W of carrier when running the PA on LV B+, perfect for 
> driving an amp, and no power wasted in a big honking resistor. 
> 73,
> -Larry/NE1S



   For my Ranger / amp situation, I originally looked at doing exactly 
this.  I have a couple of reservations - first is that the LV Supply will 
have to stand the additonal load over the long haul, and second that I'd 
really rather the mod section be running at "10 on the knob".

   Also, the resistor, if variable (even the 'slider' type) allows one to 
adjust the output as needs be - I want to run RTTY which is even more 
severe than AM in terms of overall duty cycle , and I want to spare my old 
amp (an Ameritron AL-80) as much as possible.

   Then again, I have the schematics for the "attenuator" as Johnson called 
it - to go between the Ranger output and linear input.



  And of course there a lots of topologies that will accomplish the task of 
lowering the output of a tetrode or beam-power RF section without 
upsetting the relative current balances.

   Mebbe I oughta should by a junker Ranger... Just In Case...   ;}


Cheers

John  KB6SCO




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