[Elecraft] Gamma Research Very Small Switching Power Supply

[Leigh L. Klotz, Jr.]

I just did a noise test and found either no noise or almost no noise on 
all bands.

I hooked the Gamma Research supply to my K2, along with the internal 
battery.
I disconnected all other connections (RS232, key, antenna).
I set the mode to USB and the Preamp=ON and spot checked the bands from 
160 to 10m.
For each band, I turned the power supply off and on, and then the power 
supply was on, switched off the internal battery.
This kept the rig from ever being off.
When the power supply is off, the rig is running off the 5 paralleled 25 
F capacitors and the internal battery.
I also did the same test but additionally removed the DC coax plug from 
the K2 power jack.

I noticed a slight increase in noise floor on 14.060, but I could not 
reliably reproduce it, nor did it show up on the S meter.
All other bands I could not find a difference in noise floor or birdies 
between off and on.

Leigh/WA5ZNU

>>    The Q of a 5 Farad capacitor is not good. It will carry the peak 
>> current from a SSB transmitter but it will not control RF noise. This 
>> comes from the high frequency chopping of the input 120 Volts. MFJ 
>> has some inductors and low value caps in their power supply to 
>> control RF noise.
>>
>>    A 5 Farad cap is not cheap. I guess that is why it is more expensive.
>>
>