[Premium-Rx] HP 8649B?

[Carcia, Frank A. HS]

John,
I would be interested in how you reduce intermodulation. I have a pair I use
for
dynamic range testing. I only have 6 dB pads around my power combiner but
have noticed the isolation could be better.
My combiner is homebrew with about 26 dB of isolation. I let them warm up
for a couple hours when I want do anything serious. fc

-----Original Message-----
From: John Wilson [mailto:johnwilson at freezone.co.uk]
Sent: Wednesday, August 20, 2003 1:27 PM
To: Alberto di Bene
Cc: premium
Subject: RE: [Premium-Rx] HP 8649B?


I run an EMC Test House in UK and check every signal generator that comes
through my hands. I use a Rohde & Schwarz SMY and an SMH in EMI testing and
neither of them compares with the 8640B. At home I have two good 8640Bs
which I use (with modifications to reduce generator intermodulation) for two
signal testing, and I also have an H-P 8648B and 8657A. The 8640B beats all
of them for close-in phase noise. I would like to try an 8662 but can't
afford the price tag, even second hand. Problems I have observed with the
8640B are a frequency "wobble" which can be caused by vibration from the
cooling fan in earlier units, and of course the nylon gears which everyone
knows about. I sadly have not experienced an SMDU but I have good
relationships with R&S so maybe I can borrow one to test. I'll let you know.
John

-----Original Message-----
From: premium-rx-bounces at ml.skirrow.org
[mailto:premium-rx-bounces at ml.skirrow.org]On Behalf Of Alberto di Bene
Sent: 20 August 2003 19:44
To: premium-rx at ml.skirrow.org
Subject: Re: [Premium-Rx] HP 8649B?


Has anybody ever compared the HP 8640B with the Rohde  & Schwarz SMDU ?
I have just bought the latter on eBay for a good price, but I don't have
an 8640B
to compare it with.  Functionally they are similar, though with a very
different look,
but how do they compare as far as phase noise or shielding are concerned ?
Thanks.

73  Alberto  I2PHD




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