Message-ID: <000201c27ee2$246c9640$ea3f7ad5@main>
From: "Alan Melia" <Alan.Melia@btinternet.com>
To: "LF-Group" <rsgb_lf_group@blacksheep.org>
Date: Tue, 29 Oct 2002 00:28:06 -0000
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Subject: LF: SPM-12 & PS12
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Hi all, well done Tracey...that sounds like a very reasonable price. I would
be interested.... if I had not already got a pair.

I presume they have the optional 25Hz filter and the synchroniser. I used
the PS-12 in locked mode to provide a reference signal when looking for
ZL6QH (the counter is not accurate enough so it was measured externally to
0.1Hz  with a calibrated counter)  After several hours warm up, I left the
system running  through the night and I think the drift of the locked source
was about 0.75Hz in 10 hours. The PS-12 will also 'key' via a 5-pin (270)
DIN socket on the rear apron. This is supposed to be soft switching of the
source for some of the S/N tests that one might want to do. I have not yet
determined what the time constant employed is but it should be adequate for
QRSS. Just one problem (once again not verified by experiment yet) but I
believe from looking at the circuit that the keying will be "upside-down"
i.e break for mark, and  make for space.

The locking of the PS-12  to the synchroniser in the SPM-12 is a lot easier
than the SPM-3 /  PS-3 combo where three 4mm plug leads ( or one of the
special patch leads ) is required. As Dick says you just connect a BNC coax
patch lead between the appropriate sockets on the rear panel of the two
units. The PS-12 senses the connection and kills its internal free-running
oscillator. You will need to do a calibration check if you are using the
25Hz filter to make sure the PS-12 is in the middle of the SPM-12
filter....there is a "twiddle" to correct this. As one might expect the
leveling is excellent and good to 0.1dB so one can sweep through a filter
and there is a DC output which is effectively the meter deviation which can
be sent to a plotter or A/D. The output is linear so you will have to record
the range (I am not sure, but there is probably an digital output of this)
The pair can also be swept with the aid of a WZ-6 (if anyone comes across
one) alternatively a sweep generator in the 14Mhz range will do almost the
same job. The usual way of sweeping is to leave the SPM-12 on "wide-band", I
believe.

Nice toys....enjoy them if you can find the space..... they are not small !!

Cheers de Alan G3NYK
alan.melia@btinternet.com