[CQ-Contest] FT-920 Performance Tests
w2vjn at rosenet.net
Mon Jun 23 07:53:52 EDT 1997
Recently the opportunity to check out an FT-920 presented itself. This is
not a complete run down, but it provides some of the test results that
don't normally show up in the magazines. Comparisons are shown for the
IC-765 as a reference.
FT-920 PERFORMANCE TESTS S/N 7F020105 6/12/97
Conditions: stock SSB filter, CW-optional 500 Hz in 8.215 MHz (YF-116C)
(Numbers in parentheses are for a reference IC-765 S/N 4616)
SENSITIVITY- CW Noise Floor = -138 dBm, 14 MHz (-133)
= -140 dBm, 50 MHz (-140)
SELECTIVITY- Small signal, AGC off, SSB = 1160 Hz @ -3 dB (1020 Hz)
" " CW = 490 Hz (330 Hz)
Large signal, AGC on, SSB = 1160 Hz (2260 Hz)
" " CW = 920 Hz (680 Hz)
BIRDIES- Several internally generated signals are present on each band with
levels ranging from 2 to 7 dB above the noise floor.
AGC - 2 dB increase from S1 to S7, then flat.
Rise = <2 ms, Fast (3 ms.)
Undershoot = 10% Fast, negligible Slow (none)
Overshoot = 30%, all speeds. Small signal to large. (7%
Recovery = 100 ms Fast, 150 ms Slow (30 ms Fast, 0.6 sec Slow)
RECIPROCAL MIXING -phase noise
Measured with the radio offset from a crystal oscillator by the amount
indicated and adjusting the input level to raise the noise floor 3 dB.
Offset IC-756 IC-765
3 kHz -63 dBm, S9+10 -44 dBm, S9+38
10 kHz -41 -30
20 kHz -35 -23
S meter readings above are for the indicated tone level on the respective
POWER OUTPUT-power supply set to 13.8 VDC
Band Tuner off Tuner on
1.8 MHz 92 watts 86 watts
3.5 96 88
7.0 95 82
14 95 82
21 98 85
28 99 91
50 85 72
KEYING - tested at 40 meters, no frequency effects noted.
Rise time = 3 ms.
Fall time = 1.5 ms.
Delay to RF out = 16 ms.
Character shortening = 40 ms key down provides 36 ms dots in VOX mode
and 30 ms in BK-IN mode.
SPEECH PROCESSING -average power increase due to processing.
Peak power output is 100 watts. White random noise is put into the
mike input and the level is adjusted for an ALC reading according
to the instruction manual.
Average power output, no processing = 30 watts (17 watts)
Average power output, with processing = 36 watts (42 watts)
COMMENTS - Good Features.
1. Sensitivity is excellent and compares to the best radios.
2. DSP compensates for lack of cascaded filters in uncrowded band
3. AGC performance is excellent.
4. CW Keying is excellent in VOX mode.
5. The slight tilt in the AGC characteristic will help readability when
more than one signal is in the passband.
6. Radio has lots of excellent operator features for both SSB and CW.
COMMENTS - Could use improvement.
1. Phase noise performance is not as good as it could be.
2. CW keying is shortened in break in mode. This is adjustable for the
built in keyer only.
3. AGC pumps when DSP bandwidth is narrower than filter for signals in
the filter bandwidth. This will degrade performance in pile ups.
4. The front panel is 2.5 inches wider than the radio chassis. This
space is empty inside the cabinet.
This radio has good features and performance for its price. It handles
well when operating CW. It was supplied by K0MD for evaluation.
George Cutsogeorge, W2VJN
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