[Premium-Rx] Clean LOs

[Carcia, Francis A HS]

    Brian,
What would you consider a good synthesizer? I agree the layout of the 6830
synthesizer needs some help. I have not found the correct setting of the
analog compensation. Also The phase noise gets worse when the AUX output is
connected. I suspect the grounding of the VCO connectors and
cables need termination to the case. I plan to build my own VCO. I have a
mini circuits VCO running
4X that I might try. I would use local voltage regulation. I have checked a
number of receivers and yet to find one better. The closest was the old WJ
8718.   fc 
-----Original Message-----
From: Brian D. Comer [mailto:bcomer at cox.net]
Sent: Friday, February 11, 2005 10:26 PM
To: premium-rx at ml.skirrow.org
Subject: FW: [Premium-Rx] Clean LOs


 
 
-----Original Message-----
From: Brian D. Comer [mailto:bcomer at cox.net] 
Sent: Friday, February 11, 2005 4:00 PM
To: 'Michael O'Beirne'
Subject: RE: [Premium-Rx] Clean LOs
 
I do not support the idea that frequency synthesizers are necessarily a
problem and would not consider the using of anything else for a high
performance receiver today. That is not to say that they are necessarily
good and I find the ones in the RA 6830 an example of a bad design or at
least bad implementation. There are of course may other very poor
synthesizers out there.
 
On the great HP 8640, many years ago I had access to one when it had only
just been released to the market. I took it home and used it as an LO for a
home brew 2 meter transceiver. The reports that I received were that I had
very bad FM on the my signal. The HP 8640 uses a frequency locked loop which
can very easily be frequency modulated by strong signals, so take care when
use it as an LO.
 
73 Brian
 
KF6C/G3ZVC
 
-----Original Message-----
From: premium-rx-bounces at ml.skirrow.org
[mailto:premium-rx-bounces at ml.skirrow.org] On Behalf Of Michael O'Beirne
Sent: Friday, February 11, 2005 1:49 PM
To: Premium-Radio
Subject: [Premium-Rx] Clean LOs
 
Dear All,
 
One quick idea to see what a really clean LO can do for a receiver might be
to disable the internal synthesiser and feed in some RF from a good HP8640B
genie or similar from R&S.  G3OSS (Angus McKenzie) did this at VHF with a
professional VHF receiver and was much impressed.
73s
Michael
G8MOB
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