[Milsurplus] Wireless Set No.19 MK II Panel Markings
Ian Wilson
ianmwilson73 at gmail.com
Mon Jan 19 14:33:42 EST 2009
The variometer consists of two functional parts:
- variable inductor (plus capacitor for DC isolation)
- current transformer, rectifiers (for AE current metering)
The function of the variometer is to allow the use of antennas
that are electrically short (i.e. capacitive at the operating frequency),
for example, vehicular whip antennas.
Any inductor of reasonable Q and sufficient power handling
capacity would perform the same function as the variometer
(but wouldn't be nearly as cool).
If you are going to operate with a 50 ohm antenna you will need
to match or transform it so that it presents a radiation resistance
of a few ohms to the 19 Set. Combining this with a lowpass
characteristic would be a good idea from the point of view of
harmonic suppression.
The AE current measurement part is optional. From the point
of view of RF matching, it doesn't exist.
73, ian K3IMW
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