On Sun, 2008-05-18 at 16:24 +0200, Werner 'Joe' Jochem DK7VW wrote:
> Thanks to VE1BN and K1FK who gave me valuable advice via email.
>
> After having checked the problem again, I have to correct my fault
> description:
>
> In fact these are no typical key clicks but it is a broadband hiss in
> the rhythm of CW. When using lowest output power possible I can hear it
> practically all over the bands with a second RX. This occurs on all
> bands from 160 to 10 mtrs.
>
> 73 Joe DK7VW
>
Sounds like phase noise which can be as much a receiver problem as a
transmitter problem. The biggest source of phase noise from the
transmitter should be the VFO synthesizer. Be sure the receiver input is
well protected by good shielding and an attenuator with 60 dB or more
loss when checking the transmitter with a second receiver in the shack.
If the PLL loop filter in the VFO synthesizer has a failed capacitor
(might even be a miniature electrolytic) that could increase phase noise
a whole lot, as could a receiver with lots of inherent phase noise. It
is difficult to separate transmitter and receiver effects when the
transmitter signal overloads the receiver RF and mixer stages. Reducing
the signal drastically with an attenuator helps that separation a whole
lot, providing the receiver has adequate shielding so it can't detect
the strong local signal without antenna.
73, Jerry, K0CQ
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