Actually, being primarily an older portable (?) FM service monitor, the
Spectrum analyzer in the FM/AM 1100s is a bit crude. It
claims 2uv sensitivity 300kHz-999.9999MHz for the receiver section. There is
an internal 100w continuous dummy load with a 20db
port feeding an additional 60db of attenuation before the 1st mixer. There are
a couple of intervening relay contacts and Hi-side
injection is used (1200-2200MHz from the "MHz" VCO) 1st if is 1200MHz with a BP
filter, then mixed again with 1079-1080MHz "kHz" VCO
for a 120 MHz IF that is split to the Spectrum analyzer and receiver modules.
The actual Spectrum analyzer module is useable
MHz-1GHz with continuously adjustable dispersion from 1MHz - 10MHz span with a
fixed 18Hz sweep. Input level at one point was
calibrated to within +_ 1db of the graticule marks in the center of the scale,
but fall as much as 4db, 500kHz away and 10db, 5MHz
away at max dispersion. Signal resolution is 30 kHz so it doesn't tell you
much of anything of the signal except that it's there.
Dynamic range is spec'd at the antenna port as -30 to -100dbm. There is no
scan. Thumbwheel switches control the PLL's so you have
to manually flip up and down in 10MHz increments to search. No peak storage.
I'll have to upgrade someday soon, but at least it
works and nobody touches it but me.
Apparently there is something happening in the TX port path that doesn't happen
through the antenna port. One of the relays in that
path may be getting used up.
Jim, ac6tk
----- Original Message -----
From: "Tom Rauch" <w8ji@contesting.com>
To: "AMPS" <amps@contesting.com>; "J. Bradshaw" <ac6tk@cybertime.net>
Sent: Tuesday, January 02, 2001 02:48
Subject: Re: [AMPS] 6146 splatter help?
:
: > and went into the IFR's antenna port. So now with the CW input reduced to
: > 10 db below the top line, everything is fine clear down to the baseline.
: > Now it couldn't be overloading the TX port on a 100w CW signal, 5db below
: > the top line?
:
: What selectivity are you using on the IFR?
:
: What sampling or scan rate?
:
: Does the IFR have peak storage?
:
: If so how many sweeps is it making in a sample and how fast are
: they?
:
:
:
: 73, Tom W8JI
: w8ji@contesting.com
:
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:
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