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Old May 13th 07, 05:50 PM posted to rec.radio.amateur.homebrew
Jimmie D Jimmie D is offline
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First recorded activity by RadioBanter: Feb 2007
Posts: 287
Default How to reduce two-way radio's power output?


"W3JDR" wrote in message
news:hgD1i.6186$1X1.1174@trndny02...
Locate the trace that feeds switched battery voltage to the final
transmitting stage. Cut this trace somewhere between the transmit
switching circuit and the final amp stage. Insert a few rectifier-type
diodes (1N400x) in series across the cut point. Each diode in series will
lower the voltage to the final amp stage about .7V or so. For each halving
of voltage to the final stage, the output power (and consequently the
power load on the battery) will drop by 4:1. All of this assumes that the
final amplifier is well-behaved under reduced voltage conditions, which
should be true but is not guaranteed.

Joe
W3JDR

wrote in message
ups.com...
Nowadays two-way radios are getting more and more powerful, coverage
up to 8, 10 12 or more miles. Ironically, it is even harder to buy one
with only 2-mile distance.

I want to use a two radio just for short distance, for example, only
within 1000 feet. How to modify the circuit (generally speaking) so I
can extend the radio's powerful consumption? As I do not need it to
communicate for longer distance, I want it to reduce power output, so
I can use it for longer time. I know it is difficult to illustrate
without a schematics, but just in general terms, what kind of options
or in what areas can I do the modification?

One of my applications is to use 2-way radio as baby monitor for
longer distance than normal baby monitor does.




A lot of the time both the final and the driver are fed from the same source
so just one diode may have a considerable effect.

Jimmie