VE1BN:
>Can anyone tell me what extra Ten-Tec filters are required
for the stock Orion?
Don, none are required, but the Ten-Tec 217, 218 and 219
are options to the Orion:
http://www.tentec.com/HFxcvrStore.htm
Unless you are doing serious contesting, I tend to agree
with N4PY that they may not be necessary. However, I'll
probably order Inrad's 400 Hz filter, but not the 1800 or
250 Hz filters. Remember that Orion's standard roofing
filters are 2400 Hz for SSB and 1000 Hz for CW compared to
the usual 10-20 kHz filters in traditional designs (e.g.
FT-1000MP uses a 12 kHz roofing filter at 70.4 MHZ). So
the standard Orion will be head and shoulders above other
radios, EVEN WITH NO OPTIONAL FILTERS. Here are close-in
5 kHz IMDDR3 comparisons (remember that these were made
with Orion's STANDARD 1000 Hz roofing filter):
Close In IMD Dynamic Range at 5 kHz Signal Spacing
(ARRL Lab Results, Preamp off on 20M):
Rig IMDDR3
Ten-Tec Orion 101*
Elecraft K2 88
Ten-Tec Omni 6+ 86
Yaesu FT-1000MP 83
ICOM IC-756 Pro 80
Yaesu FT-1000MP Mark V 78
ICOM IC-775DSP 77
ICOM IC-756 Pro II 76
ICOM IC-706 MkII G 74
Yaesu FT-1000MP Field 73
Kenwood TS-570D 72
Kenwood TS-2000 69
ICOM IC-756 67
*Ten-Tec spec not yet verified by ARRL.
The reason I want a 400 Hz roofing filter is mainly
for contests, when it is not unusual for an S9+40dB
signal to be only 500 Hz away while I'm trying to hear
an S3 guy answering me. The optional 400 Hz filter
should make the above IMDDR3 measurements look similar
for interfering signal spacings of only 500 Hz!
http://www.qth.com/inrad/graphs/759.gif
Orion should be able to hear signals 25 dB weaker than
a radio with an IMDDR3 spec of 76 dB when a very strong
interfering signal is within 5 kHz (and that difference
will probably increase even more at closer signal
spacings)...that's a VERY BIG DEAL for contests or in
an unruly DX pileup on 160!
73, Bill W4ZV
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