Having read the Yaesu and the contesting reflector for a while, it seems
that both the Yaesu FT1000D and the FT1000MP have a large number of users
in the contesting community. I tried to compare the receivers performance
based on reviews
in QST in 3/1991 and 4/1996, respectively. In many respects the 1000MP
seemed to come out in the short end of the stick. On closer examination,
it turns out that 250Hz filters were used in the 2 and 3rd IF for the 1000D
tested and only 500Hz filters were used in the 1000MP. This may account
for much of the difference. Details follow.
Minimum Discernible Signal: (dbm)
1000D (250Hz filters) -128 (Pre off, 80m), -126 (pre off, 20m) , -136
(pre on 80m), -137 (pre on 20m)
1000MP (500Hz filters) -128 (Pre off, 80m), -128 (pre off, 20m) , -135
(pre on 80m), -136 (pre on 20m)
Using a filter with half the bandwidth will reduce the noise energy by half
and so I expect the mds to improve by 3db.
After adjustment:
1000MP (adj. to 250Hz) -131 (Pre off, 80m), -131 (pre off, 20m) , -138
(pre on 80m), -139 (pre on 20m)
Blocking Dynamic Range: (dbm) |blocking level - mds|
1000D (250Hz filters) 138 (pre off, 80m) 143 (pre off 20m) 137
(pre on 80m) 154 (pre on 20m)
1000MP (500Hz filters) 140 (pre off, 80m) 142 (pre off 20m) 139
(pre on 80m) 137 (pre on 20m)
Using a filter with half the bandwidth might improve the blocking level by
3 db (less energy from the blocking signal, and
assuming that 20KHz away the energy level is propotional to bandwidth for
small bandwidths.) The MDS improves by
3db too. Hence the BDR might be expected to improve by 6db. Making these
adjustments:
1000MP (adj. to 250Hz) 146 (Pre off, 80m), 148 (pre off, 20m) , 145 (pre
on 80m), 143 (pre on 20m)
Third Order Intermod. Dynamic Range: (dbm)
1000D (250Hz filters) 98 (pre off, 80m) 98 (pre off 20m) 94 (pre
on 80m) 98 (pre on 20m)
1000MP (500Hz filters) 94 (pre off, 80m) 97 (pre off 20m) 91 (pre
on 80m) 94 (pre on 20m)
This is the one that really got me going on the project. The MP has PIN
diodes in the front end and should have
done better.
Using a filter with half the bandwidth might improve the intermod level by
3 db (less energy from the intermod signal, and
assuming that 20KHz away the energy level is propotional to bandwidth for
small bandwidths.) The MDS improves by
3db too. Hence the 3IDR might be expected to improve by 6db. Making these
adjustments:
1000MP (adj. to 250Hz) 100 (Pre off, 80m), 103 (pre off, 20m) , 97 (pre
on 80m), 100 (pre on 20m)
Third Order Intercept (dbm)
1000D (250Hz filters) 19 (pre off, 80m) 21 (pre off 20m) 5 (pre
on 80m) 10 (pre on 20m)
1000MP (500Hz filters) 12 (pre off, 80m) 14 (pre off 20m) 1 (pre on
80m) 5 (pre on 20m)
Adjustment for 3db narrower filter: While the desired signal output may
remain almost the same, the intermodulated
output would increase by 3db. Because of the difference in slopes, this
will shift the intercept point by 6db.
1000MP (adj. to 250Hz) 19 (Pre off, 80m), 21 (pre off, 20m) , 7 (pre on
80m), 11 (pre on 20m)
The Bottom line:
1. (comparing mds and intercept with pre on) The mp seems to have much
better preamps than the 1000 did.
Better mds and better intercept. With pre off, they are pretty much the
similar receivers.
2. (comparing 3IDR) 2 to 5db better, possibly because of pin diodes in the
front end.
I recently purhcased a MP.
Regards,
Rajiv Dewan, N2RD
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