"Jay in the Mojave" wrote in message
...
Hello DR. Death:

R4 and D2 make up the Bias voltage and current that is feed to the
base's of RF Amplifier Transistors Q3 and Q4.

The resistance value of R4 will be a dead nuts on requirement. But may
not really need to be a exact value, within a certain range. R4
resistance value was probably called out 47 Ohms as this will work.

I would use 4 each, 2 watt resistors wired in a parallel/series way to
make a 8 watt resistor, as a 6 watt resistor is needed.

My simple diagram shows 4 each, 47 ohm resistor wired in a series
parallel method. This allows the resistor to have the same value as a
single resistor but 4 times the power rating.


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http://www.communication-concepts.co...63300sharp.pdf

Jay in the Mojave



DR. Death wrote:

I received the board today along with the Motorola engineering bulletin
and
a list of construction hints and ran across my first problem. The
bulletin
lists R4 as 33 ohms. The construction hints lists it as 82 ohms. The web
site resistor package lists it as 47 ohms. Hopefully they can clear this
up
for me. I'll post the results when I get a reply.


The bulletin uses a 1N4997 diode for D2 and a 33 ohm for R4. The
construction hints uses a MJE243 Transistor for D2 as they state the 1N4997
is no longer available and R4 as 82 ohms. The 63R resistor parts set has it
at 47 ohms. So the choice I think would be either the 47 or 82 ohm.
I was able to find a 1N4997 replacement NTE5800 and might try it with the 33
ohm as the MJE243 will be a bit harder to install as it goes between the PCB
and heat sink and has to have a spacer. Thanks for your input, if the 1N4997
doesn't work like expected I'll give the series parallel a try.