I had two RA 6830 receivers one a -JD and the other marked –516.
I
noticed when I first received the first, the –JD, that the phase noise was not
good for CW reception. Both of the receivers had linear power supplies. I have
made one mod
to the -JD receiver adding additional capacitance across R3 on A2.
A
requirement came up to operate the –JD from a portable supply. A battery pack
was built to enable this. The battery pack also enables one to look at the phase
noise of the receiver without the problems introduced into the frequency
synthesizer by what appears to be a ground loop within the receiver.
The following are pictures show the close in phase noise on both receivers and in the case of the –JD when operating from batteries (-24V, +12V, +18V, +24V).
The -516 has had an additional LM7805 regulator added to separately supply A6 at sometime.
RA6830-JD,
powered by built in linear power supply, phase noise (synthesizer noise) in 1
KHz span.
RA6830-JD, powered by built in linear power supply, phase noise (synthesizer noise) in 10 KHz span.
RA6830-JD, powered by external battery pack, phase noise (synthesizer noise) in 10 KHz span.
RA6830-JD, powered by external battery pack, phase noise (synthesizer noise) in 1 KHz span.
RA6830-516, powered by built in linear power supply, phase noise (synthesizer noise) in 10 KHz span.
RA6830-516, powered by built in linear power supply, phase noise (synthesizer noise) in 1 KHz span.
