[1000mp] if mod installed

[Tom Rohlfing]

For what it's worth...  Last December I brought home from work a Hewlett
Packard HP E 4432B calibrated RF signal generator.  I used this to perform
some careful measurements of the S-meter calibration (or rather, lack
thereof), and also to measure the minimum detectable signal (MDS).  I made
these measurements near the bottom of the CW portion of each band.  (They
say some hams use the phone part of the band too.)  For each frequency I
measured 8 conditions:  4 IF bandwidth settings, and then Flat or Tuned,
making 8 total.  Note that I have the stock MP filters, plus an Inrad 400
KZ. in the 455 IF, and a pair of Inrad 250s in the 250 position.

If you are not familiar with these MDS numbers, they are absolute power
measurements, in dBm.  So -141 means 141 dB smaller than a 1 milliwatt
signal, assuming a 50-ohm system.  For reference, S9 is often defined to
be -73 dBm.

Note that the Flat/Tuned setting doesn't make any difference on 30M, 20M,
17M, and 15M.  But interestingly, the tuned setting makes it more sensitive
in the upper bands, and less sensitive in the lower bands.  No doubt there
is some good reason for this.  Perhaps it is related to the higher amount of
atmospheric noise in the lower bands.

For the sake of trying to be objective, I adjusted the RF signal generator
at each setting to the level which just barely started to show a
recognizable line on my sound card waterfall spectrum display (like the
PSK31 programs that are all around these days).  I think that made it more
consistent than just making the adjustments by ear.

                      FLAT                            TUNED
IF BW   6      2.4   0.5   0.25         6     2.4   0.5   0.25

FREQ
  1820 -141 -143 -144 -143      -133 -137 -137 -136
  3520 -141 -144 -144 -143      -125 -129 -129 -129
  7020 -137 -140 -140 -140      -132 -135 -136 -135
10120 -140 -143 -143 -143      like flat like flat like flat like flat
14020 -140 -143 -144 -144      like flat like flat like flat like flat
18080 -141 -143 -143 -143      like flat like flat like flat like flat
21020 -142 -143 -143 -143      like flat like flat like flat like flat
24910 -140 -143 -143 -142      -147 -146 -146 -146
28020 -141 -143 -143 -143      -147 -147 -146 -147

If you are interested in the S-meter stuff, Greg Ordy, W8WWW was kind enough
to include my results in his very fine web page about S-meters.
http://www.seed-solutions.com/gregordy/Amateur%20Radio/Experimentation/SMete
rBlues.htm.  Click on the link that says Yaesu 1000MP:  More Data

Hope this is helpful.  Having said all that, I actually don't know whether I
am using Tuned or Flat for each individual band.

73,
Tom / W7GT

From: "Phil ON4VP" <emailgroups@wanadoo.be>
To: <1000mp@mailman.qth.net>
Sent: Monday, September 23, 2002 1:32 PM
Subject: [1000mp] if mod installed


> Hello,
>
> I've received the IFmod today.
> I installed the board as described.
>
> 1) My default menu 91 setting was '12'
>     To what number have people here reduced this ?
>     the manual states 1 or 2 clicks ...
>
> 2) To what setting have people here set ther front end preamp ?
>     'Flat' or 'Tuned' ?
>
> Thanks for filling this in ...
> Phil ON4VP
>
>
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