Re: Test Results IC-7000 2 Meter Rpt Problem Transmit

D C *Mac* Macdonald
 

I certainly concur with the possibility of too high overall deviation as outlined below by Paul Hansen!  Excessive peak deviation can totally eliminate the "carrier" and cause squelch dropout.  The same can happen even without tone access if the transmitting station is weak into the repeater.  

The natural tendency when signals are weak is to talk louder into the microphone.  This is absolutely the worst possible thing to do!
 
73 - Mac, K2GKK/5​
(Since 30 Nov 53)​
k2gkk hotmail com​
Oklahoma City, OK​
USAF & FAA, Ret'd​
Icom User a/o '72​
 


From: ic7000@groups.io <ic7000@groups.io> on behalf of Paul Hansen <pwhansen@...>
Sent: Thursday, April 18, 2019 15:30
To: ic7000@groups.io
Subject: Re: [ic7000] Test Results IC-7000 2 Meter Rpt Problem Transmit
 

It is possible the deviation of the 7000 is set too high. That causes the sub-audible tone to exceed the receiver pass band and the receiver will drop out. Your deviation should be between 4.5 and 4.8Khz with CTCSS turned on. Or, around 4.0 to 4.2 with CTCSS turned off. A test is to see if your 7000 opens the squelch on your 530 with no modulation. Do not talk. If the squelch remains open then it is possible the total deviation is too high. I just checked the service manual. There does not seem to be any adjustment for deviation at all.

 

Thank you,

 

Paul W. Hansen, W6XA

Amateur Radio Service

2134 Carthage Road

Tucker, GA 30084

(864) 222-3539 office

www.amateurradioservice.com

 

 

From: ic7000@groups.io [mailto:ic7000@groups.io] On Behalf Of Kurt Sweeny
Sent: April 18, 2019 15:52
To: ic7000@groups.io
Subject: [ic7000] Test Results IC-7000 2 Meter Rpt Problem Transmit

 

Based on the groups shared insights I decided to do some testing using my FT-530. The results were interesting.

 

Testing hypothesis: I should be able to hear one of the higher frequency ~200hz. Even with my ears. Can the 7000 open the tone squelch on the FT-530? And just for interest can the 530 open the tome squelch on the 7000?

 

Setup:

Power out: on 530 .1 watts, on 7000 1 % (~.5 watts )

Load: 530 into rubber duck; 7000 into MFJ 200 watt              dummy load

 

Results:

The FT-530 reproducibly opened the tone squelch on the 7000, 100% good audio, no drop outs. Now comes the interesting part. The 7000 did not open the squelch on the 530 using 100hz tone. At tones above 200hz the 7000 opened the squelch on the 7000, sort of. The tone on the 7000 could be heard but appeared to be intermittently pulsing not constant. When the tone pulsed the squelch would open and a few syllables of test 1,2,3 counting could be heard. The relationship between tone frequency and the 7000 was hard to reproduce.

 

Discussion / Questions

 

Well the tone detection of the 7000 seems to work; not sure if that means anything about the heath of the encoding circuitry . The 7000 was intermittently encoding and could let a few syllables of audio through. I am thinking that the relationship between tone frequency may have been erroneous, that I read into the intermittence.

 

Any thoughts appreciated. Are there parameters somewhere deep in the menus that I should check such as deviation? Is the tone generation on its own board that I might swap? Any individual component that might be suspect that I could swap out?

 

Kurt

KD6LZV

 

 

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