[Amps] 50 Ohm Loads

[Jim Tonne]

Guys:

If a .01 uF cap was used in series with a load
to tune it to 1 MHz,  then the load had an inductance
of 2.533 uH.  The return loss would be 20 dB or
better over the range of 750 kHz to1320 kHz.  I
find these numbers believable.  If you use such a
load in a hamband application I spose it would be 
quite good over one band but surely not a wideband
load for general testing.

If you use that 50 ohm resistor with its 880 uH
inductance you will need to tune it to 1 MHz with a
capacitor of 28.78 pF.  The 20 dB return loss 
bandwidth will be plus and minus 3200 HERTZ!
Don't even THINK about using that resistor in a
dummy load at ANY frequency!

That resistor must have a huge number of turns on
it;  couple of hundred or more?

By the way, those VLF transmitters used by the
Navy have antennas that have huge values of
capacitance in their equivalent circuit.  So they
are brought to resonance using similarly-huge
values of series inductance.  Result:  truly narrow
bandwidths, just barely adequate for narrow-shift
teletype.

Oh yes.  If it was "Gates" personnel that tuned the
dummy load, then the frequency units were 
probably cycles per second, not Hertz.   :-)

- JimT