"Doing a low drive mod on Alpha 76CA. Saw five 470 ohm 2W composition carbon as
recommended, hard to find. Will modern carbon film or metal film resistors work
or are the inductive enough to screw things up?"
Carbon comp resistors are not good long term choices. They change resistance
just sitting on the shelf (years), absorb moisture and more importantly change
resistance when they are run near their rating. Many years ago, I wanted to
use some 2 watts resistors in a commercial product and made tests to see if I
could "age" them to become more stable. In open air, I took 2 watt resistors
and ran them at 2 watts for 1 minute, then cooled them down. The resistance
changed permanently. So, I ran the same test again, with the resistor changing
to a new value after it had cooled down. I kept running the test and the
resistor kept changing value, although at some point it started going in the
opposite direction.
Many of the resistors made today have the resistance on the surface and
material is removed in a spiral manner, so they can have inductance. However,
it is often very slight and will vary depending upon value. The manufacturer
will have the information available.
In the value you need for the Alpha, you can make up the required assembly then
check it on something like the MFJ vhf bridge. See if the resistance changes
with frequency. A network analyzer or more sophisticated device is better, but
may not be necessary.
73, Colin K7FM
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