TopBand: InRad FT1000MP Mod: Good for 160?

[Earl W Cunningham]

Tyler Stewart, k3mm@erols.com writes:
"This mod will do absolutely nothing for you on 160 meters."
=====
I vehemently disagree with that statement!  I also thought that the band
noise on 160m dictated weak signal readability rather than the receiver's
noise floor.

I was disappointed after spending more than $2500 for my new MP to find
that my 18-year-old TS-830S  still heard weak CW signals on 160m slightly
better than the MP.  I was elated to find that, after installing the
INRAD front-end mod in the MP, that the MP was slightly better than the
TS-830S.

 The fact is, and this has been verified by quick-switch tests of a
steady on-air weak signal source on 160m, the mod definitely improves
weak CW signal reception on 160 meters.  This might not be the case for
SSB signals (where BW necessarily must be 1500 Hz or more) on 160m, but
for CW when using 250Hz filters and the DSP 60 Hz filter (a *must* for
improving S/N for 160m weak signal work) the INRAD mod very definitely
improved the MP.  The tests were made using my transmit 160m phased array
as the receiving antenna.
=====

"The mentioned Capacitor mod is not an INRAD mod per se, but was
initiated by a 9 lander who had discovered that some early MP's had the
wrong capacitors installed on the audio board.  Both of mine, one of
which is fairly old already had the proper caps installed."
=====
My MP was manufactured in February 1998 and had the "wrong" capacitor
installed. The K9AN capacitor mod got rid of the annoying IF hiss in the
CW mode.  The INRAD front-end mod reduces this hiss (because you reduce
the IF gain), but correcting that audio filter network with the capacitor
is what really makes the difference in hiss.  The capacitor mod has no
noticeable effect on SSB.

There seems to be no sure way of knowing if your MP, old or new, has the
correct capacitor other than visually checking the values of audio filter
components R3018, R3019, C3015, and C3026 on the MP's audio board.

73, Merry Xmas, de Earl, K6SE (a veteran topbander)


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