Jesse,
While your method may work, it likely won't be clean; not ever a good
thing, especially where a repeater transmitter is concerned. The Micor
VHF transmitter, like most FM transmitters, uses Class C RF
amplification. When a Class C amplifier is under-driven, or turned down
below about 50 or 60% of its capability, it can become unstable -
spurious. It is much better to select the number of stages, and
properly drive them to create the amount of power output required. This
also results in the best efficiency, and since you won't have excess
power to burn in a solar situation, the method I suggest is likely better.
Jesse Lloyd wrote:
That PA mod is awesome. I was considering knocking down the power out
of the exciter to 20 mW by increasing the value of a couple resistors,
and then feeding it into a 40 Watt M100 PA. From there I have the
ability to vary the output power from 5-40 watts (ish).
Jesse
On 8/22/07, *Kevin Custer* <[EMAIL PROTECTED]
<mailto:[EMAIL PROTECTED]>> wrote:
Jesse,
You can put a toggle switch on the B+ line going to the Audio PA,
this will cut several hundred mA of current draw from the Class AB
audio section, and allow it to be connected/turned on when service
is required.
Since you are working on a VHF unit, you can review the mods on
this site where I took a 110 watt PA, hack-sawed it in half, and
made a 5 to 12 watt PA that is very power efficient:
http://www.kuggie.com/ahra/hmftinfo.html
I've also been successful in doing the same with only one
transistor (the controlled stage) and created a .5 to 2 watt PA.
