ICOM IC-R8500 and IC-R75

ICOM IC-R8500 and IC-R75

Post by Syso » Mon, 02 Aug 1999 04:00:00

    I've been messing around these few days with the ICOM IC-R8500 and
IC-R75 with a Timewave PK-232 DSP TNC and TImewave DSP-599zx filter and
I've noted a few things about the radios that other people who own these
radio might what to know.

    The R8500 has a much better audio range for voice reception without
distortion than the R75. Note that I have the DSP card in the R75.
However, when it comes to recv. CW, RTTY and WeFax the R75 blows even a
IC706II out the water! Yep...better than the IC-706II. At this point I
should also mention that both the R8500 and R75 have a 500 HZ CW / RTTY
filter installed ( THe R75 also has 1.9 SSB filter installed).

    When using the R8500 with the DSP-599zx filter I can control the
audio bandwidth to a better degree to kill noise and nearby signals.
Using the DSP filter with the R75 and it's installed DSP filter doesn't
help much because the R75's DSP cuts the audio range already to narrow
so when the audio gets to the external DSP filter it's like straining
noodles twice. Little or no difference with both DSPs in-line.

    So it looks like the R8500 is better that the R75 for AM / SSB voice
work....not in all cases. If I find a very low signal ( Voice or CW /
RTTY) the R75 pulls it out 50% clearer than the R8500. If the signal is
strong the R8500 wins in AM/ SSB quality. This maybe to the fact that
the NB in the R75 is adjustable and it's hard to adjust for all signal
situations. If the NB is adjusted too narrow AM / SSB will be more
distorted but CW / RTTY will sound better. THings that make you go
Hmmmmm.

    The R8500 is, in my view, too wide to say it's great on all bands.
The R8500 is better than your regular scanner or flat desktop general
coverage radio. Both the R8500 and R75 are lacking in stock filters for
the price. The R75 can be setup easily for a wide range or HF / CW/ SSB
conditions. The R75 allowed me to change my RTTY tone and shift quickly
as well as the CW tones that went into the external TNC.

    I found these radios great to use together when listening to spit HF
voice channels and VHF / HF satellite links. The ability to use the
radios CI-V transceive controls help a lot in signal chasing on HF. I
use the radios in this way by having the R8500 find a base digital
signal in bad conditions then switching over to the R75 to fine tune
then decode.

    Now, all I have to do is keep tuned to mainland China to see if they
want to launch a missile at my antenna!

James
SysOp: World Data Exchange - Taiwan
WEB BBS: http://wins.twwde.com.tw