[ARC5] Fwd: SCR-274N Antenna Matching

[Dennis DuVall]

Begin forwarded message:

> From: Dennis DuValll <w7qho at aol.com>
> Subject: Re: [ARC5] SCR-274N Antenna Matching
> Date: August 22, 2014 10:41:57 AM PDT
> To: Arc5 at mailman.qth.net
> 
> 
> This seems to be a perennial discussion topic on this thread.    In my LONG term experience (60+ years) with these little beasts a simple series cap is sufficient for matching a 50/75 ohm load, 100pf for 80/75 and 50pf for 40M.  Cut in the variable link to about 25 %, peak the dipped PA current with the roller inductor and then finally adjust the link to the desired (dipped) plate current.  Also  a good idea to add a short shaft extension to the PA padder cap out through the access opening on the side of the chassis to facilitate keeping  the PA properly dipped.  Also, using the same capacitor values an "L" network can be formed with the roller inductor which provides a fine match into a half-wave end fed wire.
> 
> In the recent thread the use of series caps along with an UNUN is described and, alternately, a series cap along with a shunt cap to ground.  Apparently the roller inductor is not included in either circuit arrangements?  Not clearly stated……  Also, don't understand the fascination with UNUNs and their toroidal relatives.
> 
> Enuf...
> 
> Dennis D.  W7QHO
> Glendale, CA
> 
>