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R8600 Icom IC-R8600 v AOR 8600 Mk2

Joined
May 10, 2016
Messages
170
#1
I have tried 4 different antennas on my IC-R8600 and the same antennas on the AOR 8600 Mk2. (Two of the antennas are identical) All four antennas receive well on the AOR but none of the antennas perform very well on the IC-R8600. In the video example, both the AOR and the Icom have the same frequencies programmed into their memory. I'm unsure as to why the AOR is far more sensitive to receiving weaker signals that the Icom doesn't stop on. It seems as if the Icom only stops to receive stronger signals. I have seen the Icom stop on a frequency but the signal meter doesn't register any signal strength at all; however, the AOR receives the same signal with it's signal meter pretty much full up.

 
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#2
Something is obviously wrong. The proper way to compare receivers would be to use the same antenna fed through a splitter or multucoupler to both receivers. I and most 8600 owners have found it picks things up that other receivers cannot.
 
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#3
@prcguy

I have also had an AOR 8000 Handheld receiver (using a Watson W-881 antenna) running alongside the R8600 with the same frequencies. That too receives/stops on signals the R8600 doesn't. I understand what you're saying about a Splitter/Multicoupler but two of the antennas are identical so don't see how running both receivers on the same antenna would make any difference.
 
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#4
Two identical antennas mounted 10ft apart will have some differences, but probably not as drastic as what you are seeing. I would want to go through all the menus in your 8600 to see what's up. Have you tried leaving the 8600 on a very active freq in VFO mode while the AOR is receiving the same thing? At least you could adjust squelch or other things in VFO mode to see what is causing the discrepancy.

@prcguy

I have also had an AOR 8000 Handheld receiver (using a Watson W-881 antenna) running alongside the R8600 with the same frequencies. That too receives/stops on signals the R8600 doesn't. I understand what you're saying about a Splitter/Multicoupler but two of the antennas are identical so don't see how running both receivers on the same antenna would make any difference.
 
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#5
@prcguy

Actually yes I have. I have had the AOR and R8600 on the exact same frequency and the AOR opens up the squelch when a weak signal is received -- although the audio is barely audible ... it proves the AOR is hearing the weak signal and opens up the squelch. The R8600 doesn't. Also, having the squelch open on the R8600 you can't even hear what the AOR can. No way can this be an antenna issue? I did speak to Icom about this and they said try turning the AFC setting off -- doing that not made any noticeable difference. I've had my R8600 for about 9 months and have always had concerns why my AOR outperforms the R8600 on reception sensitivity.
 

iMONITOR

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#6
I have tried 4 different antennas on my IC-R8600 and the same antennas on the AOR 8600 Mk2. (Two of the antennas are identical) All four antennas receive well on the AOR but none of the antennas perform very well on the IC-R8600. [/MEDIA]
Is it possible the ICOM has the attenuator enabled?
 

TailGator911

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#8
Is it possible the ICOM has the attenuator enabled?
What I was thinking...man this thing has more filters on it than I can count, and it sounds like something might be enabled on his radio. I would go thru the whole list of filters and settings and peruse that novella they call a User's Manual and recheck everything. Something is not right there. I will be following this one to see what develops.

JD
kf4anc
 
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#9
Setup example. Tuned to a frequency that is I believe some data channel. Here is my AOR 8000 Handheld tuned to that data channel and so is my IC-R8600. On that frequency, there are 3 transmissions. The first is very strong as can be clearly seen on the signal strength meter of the R8600. The second transmission is weaker and the third transmission is very weak. The AOR receives all three transmissions, opening up the squelch even on the weakest signal -- however, the R8600 only receives two of these transmissions. Exactly the same results on all the antennas I have tried.

Video here:

20190203_1725442.jpg
 
Joined
Aug 7, 2005
Messages
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#10
If you look at the specs the AOR AR8600 on VHF airband is 0.7uV for 10dB S/N, the ICOM R8600 requires 5.6uV, the R8600 will appear deaf in comparison on AM airband.
 
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#11
In my opinion a setting is wrong or the Icom 8600 is broken. There should be very little difference in receive quality between the Icom 8600 and any other high end receiver with the Icom more likely to receive better. My Icom 8600 out receives anything else in the VHF/UHF range I've put it up against. I've not put mine against an AOR 8600 but I did have an AOR 8600 MKIII and although it was a good receiver, it would have taken a serious back seat to the Icom 8600 at any VHF/UHF frequency and would be dark night and summer day comparing them on HF.

@iMONITOR

No. If the Attenuator was ON it would show up on the display.
 
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#13
Being a little concerned I just ran a quick test on my Icom 8600 and my Whistler TRX-1, both on 123.450MHz AM mode. I did a crude sensitivity measurement as I didn't want to break out audio cables to my SINAD meter and both the Icom and Whistler receive a .1uv AM signal modulated 30% with a 1KHz tone about the same from my IFR 1200S feeding a 10ft RG-142 BNC-BNC cable. At .2uv both receivers have a nice audible tone with some noise but its very listenable.

I squelched both radios with the Icom squelching at 30 and the TRX-1 just barely squelched with its analog knob and the Icom will unsquelch with a weak signal at .12uv and the TRX-1 closer to .11uv. That's splitting hairs, but from what I see the Icom 8600 is working just fine and is in the relm of very sensitive in the AM aircraft band.

If AOR-262 is near So Cali I could run a test on his.
 
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#14
I made a mistake, hold on!

I tested the Icom 8600 with the preamp off. I just turned it on and I can't measure it against the TRX-1 very well because my IFR is not calibrated below .1uv. Now at what I approximate is about .05uv, the Icom 8600 is about equal with the TRX-1 fed with a .1uv signal. The Icom squelched at a level of 30 now unsquelches at around .05uv which is very weak. The Icom 8600 with preamp on will easily out receive the TRX-1 fed from a signal generator. I suspect when fed with an antenna bombarding each receiver with lots of strong signals, the Icom will pull further ahead.

Can AOR-262 run any kind of sensitivity test between radios similar to what I just did?



Being a little concerned I just ran a quick test on my Icom 8600 and my Whistler TRX-1, both on 123.450MHz AM mode. I did a crude sensitivity measurement as I didn't want to break out audio cables to my SINAD meter and both the Icom and Whistler receive a .1uv AM signal modulated 30% with a 1KHz tone about the same from my IFR 1200S feeding a 10ft RG-142 BNC-BNC cable. At .2uv both receivers have a nice audible tone with some noise but its very listenable.

I squelched both radios with the Icom squelching at 30 and the TRX-1 just barely squelched with its analog knob and the Icom will unsquelch with a weak signal at .12uv and the TRX-1 closer to .11uv. That's splitting hairs, but from what I see the Icom 8600 is working just fine and is in the relm of very sensitive in the AM aircraft band.

If AOR-262 is near So Cali I could run a test on his.
 
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#15
I made a mistake, hold on!

I tested the Icom 8600 with the preamp off. I just turned it on and I can't measure it against the TRX-1 very well because my IFR is not calibrated below .1uv. Now at what I approximate is about .05uv, the Icom 8600 is about equal with the TRX-1 fed with a .1uv signal. The Icom squelched at a level of 30 now unsquelches at around .05uv which is very weak. The Icom 8600 with preamp on will easily out receive the TRX-1 fed from a signal generator. I suspect when fed with an antenna bombarding each receiver with lots of strong signals, the Icom will pull further ahead.

Can AOR-262 run any kind of sensitivity test between radios similar to what I just did?
Did you try a 10dB S/N measurement in AM mode, unless the published spec is wrong the Icom appears to have very poor AM sensitivity which would affect VHF airband performance. The FM specs look reasonable.
 
Joined
Oct 22, 2005
Messages
189
#16
I've noticed the following on my Icom ic-r8600:

I'll power it up on 6000 kHz early morning at the start of the day and the spectrum scope activity will look dead. Then a little later, it could be a few secs or several minutes, the spectrum scope roars into life. I'll turn it off then on again and sometimes everything looks fine or the scope activity will be dead momentarily then come back to life again.

I've an AOR 8600 MkII that I haven't used in a while. I could fire it up and check sensitivity on both receivers.
 
Last edited:
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#17
I already mentioned I didn't break out any audio cables for precise measurements but I can say the Icom is more sensitive than my TRX-1.


Did you try a 10dB S/N measurement in AM mode, unless the published spec is wrong the Icom appears to have very poor AM sensitivity which would affect VHF airband performance. The FM specs look reasonable.
 
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Bothell, WA
#18
Some obvious questions:

Did you update the 8600 to the latest firmware?
Have you tried a full reset?
Is there a setting that adjusts RF Gain (usually it's a knob but I'm guessing there's an internal setting for this somewhere...)
What is FIL3? What's the bandwidth of that filter? Is your passband shift value at 0?
Is there a way to calibrate the 8600 to make sure it's on frequency? (Obviously the service manual can help you do this physically...)
 
Joined
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Messages
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#19
Some obvious questions:

Did you update the 8600 to the latest firmware?
Have you tried a full reset?
Is there a setting that adjusts RF Gain (usually it's a knob but I'm guessing there's an internal setting for this somewhere...)
What is FIL3? What's the bandwidth of that filter? Is your passband shift value at 0?
Is there a way to calibrate the 8600 to make sure it's on frequency? (Obviously the service manual can help you do this physically...)
@devicelab

Answer Yes to all of your questions except the last one. The only way to really find out if there is something wrong would be to return it to Icom.
 

Token

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#20
Being a little concerned I just ran a quick test on my Icom 8600 and my Whistler TRX-1, both on 123.450MHz AM mode. I did a crude sensitivity measurement as I didn't want to break out audio cables to my SINAD meter and both the Icom and Whistler receive a .1uv AM signal modulated 30% with a 1KHz tone about the same from my IFR 1200S feeding a 10ft RG-142 BNC-BNC cable. At .2uv both receivers have a nice audible tone with some noise but its very listenable.


I squelched both radios with the Icom squelching at 30 and the TRX-1 just barely squelched with its analog knob and the Icom will unsquelch with a weak signal at .12uv and the TRX-1 closer to .11uv. That's splitting hairs, but from what I see the Icom 8600 is working just fine and is in the relm of very sensitive in the AM aircraft band.
Reading this thread concerned me a bit. I never really use my R8600 on VHF air band more than extremely causally, just occasionally going to the local airport Unicom. So I really had not checked out the R8600 in AM and VHF.


I do not have a SINAD meter. I do have a HP 8640B and a software audio power meter (on the soundcard of one of my machines). So, what follows may not be a true 10 dB S+N/N measurement, but should be somewhat close.


R8600 was set to: 124.000 MHz, AM mode, Default FIL 1, AGC OFF, Pre Amp was tried both ON and OFF, NB, NR, ATT, IP+, NOTCH all OFF.

HP 8640B set to: 124.000 MHz, Internal AM modulation, 1000 Hz, 30% modulation.


I took the audio out of the R8600 directly to the line input of the sound card. I set the audio power meter software REFERENCE to 0 dB (raw number was about -36 dB) with Squelch OFF and no RF signal input to the R8600.

R8600 Pre Amp OFF, Squelch set to 30% (just killed static):
-118 dBm, 0.28 uV, broke squelch with usable but somewhat scratchy audio.

R8600 Pre Amp ON, Squelch set to 30% (just killed static):
-130 dBm, 0.07 uV, broke squelch with scratchy audio.

R8600 Pre Amp OFF, Squelch OFF, Audio Power meter REF set to 0 dB with no signal present:
-112 dBm, 0.56 uV, 10 dB increase in Audio Power meter

R8600 Pre Amp ON, Squelch OFF, Audio Power meter REF set to 0 dB with no signal present:
-120 dBm, 0.22 uV, 10 dB increase in Audio Power meter


Again, I am not going to claim this is a 100% valid 10dB S+N/N measurement, but it should be in the ball park.

It looks to me like the R8600, at least my copy, is adequately sensitive in the VHF Air Band.

T!
 
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