[1000mp] 1000mp menu 9-1 settings revisited

[Mark Shaum]

The following scratchpad notes from last night are offered for any of
interest on the list.  I hope the space-delimited tables come through
clear.

I recently felt my 1000mp has been a bit stingy on S-meter readings on
the lower frequencies for a while, although copy is just fine.  The main
and sub receiver s-meters have been within one bar of each other for
quite some time, I use dual receive often.  So I brought out a signal
generator, and after verifying its output at 100 and 1000 uv was within
10% of an unofficial standard on a couple of my available HP rf
voltmeters, I took some measurements.  The effect of tuned vs. flat mode
preamp is plainly visible across the bands in the first set of
measurements.  Microvolt levels were noted for S1 and S9 main s-meter
readings on various bands.

IF gain setting had been changed a bit over
the years.  Sometimes I would fiddle with it to
suit at-the-moment receiving conditions.
The original late 1997 factory setting
was 13.  It was dropped to 11 after installing the
original Inrad IF preamp.

Menu 9-1 IF gain=11

Readings are microvolts taken just as S1 and S9
meter bars became illuminated

Front end=Tuned

F    S1    S9
1.8   9   500
3.5  10   500
7.0   8   500
14    3   200
21   2.5  170
28   0.7   60

Font end=Flat

F    S1    S9
1.8  N/A  240
3.5  N/A  200
7.0  N/A  230
14   N/A  180
21   N/A  140
28   N/A  130

Definitely a stingy S-Meter. A bit of Art Collins
influence has stepped in.  (I believe Collins tended
to use 100 uv as a S9 reference rather than the more
common 50 uv).

I chose to adjust the menu 9-1 gain to set 100 uv
as the S9 point on 14 mhz.  This was achieved with
a menu 9-1 setting of 15. Results on 3.5 and 14 mhz
are as follows, with preamp type set to flat:

F   S1   S9
3.5 1.5 100
14  1.6 100
28  1.0  90

MDS was not checked.  My URM-25F generator isn't the
best for MDS checks on sensitive receivers, and I didn't
want to haul the HP 606 in from the outbuilding shack.
My QTH is fairly noisy anyway, and band noise is generally
well above the MDS level.

I find it interesting that my menu 9-1 setting is now 15, 2 above the
original factory setting, and 4 above the setting I arrived at when
installing the original Inrad IF preamp.   The sub-receiver s-meter now
averages 3 bars below the main s-meter reading as a point of interest.
It read a bit below the main meter when new, although I didn't record
the details at the time.

After seven years, I'm thinking its time for a full realignment to
re-establish some base level performance.  I'm not looking forward to
the time this is going to require although I'm sure I'll learn a few
things during the process.

------------------------------------------------------------
Mark Shaum K9TR
email: k9tr at dtnspeed.net
http://www.qsl.net/k9tr
------------------------------------------------------------