[evlatests] P band, 4 band and power levels

[Paul Harden]

Barry Clark wrote:
> But 15 dB sounds too much - it will decrease the headroom 
> available to the P band.

In the 4/P Converter, the 4- and P-band signals are combined just prior 
to the mixer.  Attenuating the 4-band signal would not affect the P-band 
power to the mixer.  The mixer is the limiting device that determines 
overall gain headroom.  At present, the higher power at 4-band causes 
the mixers to go into gain compression about 10 dB before P-band.

It would seem that by attenuating the input power at 4-band *only*, this 
would improve the 4-band headroom and leaves the P-band headroom as it 
is (about 36dB).  The 4-band attenuation would equalize the two bands to 
about the same power level, and the same headroom.

I agree that 15dB sounds too much and could start interfering with the 
noise figure.

Paul H.