IC-92AD Icom HT problem display goes blank after 144MHz transmit in DV mode

[WB6DJI]

 
Just got a new Icom Hand Held Radio IC-92AD and this happens only on 2 meters in DV transmit mode when I talk
into radio. Apparently the DV modulator has to be sending data, when you talk. Upon release of PTT, the display goes
blank.
 
This does not happen if radio is connected to 50 ohm sma dummy load.
 
The only antenna I could use to prevent this is the Maldol MH-610, all others had slightly different load VSWRs to allow this to happen ! This antenna has a broadband balun in its base to cover wideband.

I suspect it (MH-610)  has the best 50 ohm match at 144MHz and at the second harmonic 288MHz. The Maldol SMA anteena
is a broadband antenna for 144/220/440MHz.

I suspect the IC-92AD DV modulator  (mixer) in transmit mode is sensitive to 2nd harmonic load impeadance at 288MHz an the isolation between the DV encoder/decode is poor when 2nd harmonic impedance is poor at 288MHz when transmitting at 144MHz while modulaing the radio in DV mode.
 
Apparently seems to be dependent on VSWR loading of transmitter (especially at 2nd harmonic of 144MHz=288MHz)and affects the DV decoder to cause the display to go blank.
Will not happen on FM mode !!
 
Another new engineering bug (goof) brought to you from ICOM for the IC-92AD
 
Has anyone got a response from Icom about this design problem.

 
Mike Aust D-Star User on
KF6BQF B System in California
449.080MHz 
WB6DJI
e-mail : ava622(at)verizon.net
replace (at) with @ symbol

[hb9hfd]

Hello

I'm happy  to read this message as i have the same problem with my IC-E92D when I put it
in my coat pocket with the auto gps tx on. I mind it my tx but see that i'm not alone.

That append with the GPS microphone and with hi power. I'm not try in med and low.

73

Philip

[K4TJJ]

Does it do the same thing when connected to an external power source? My 91AD will do that when the battery is about 1/2 charge as it needs to be replaced.

[kb9mwr]

http://www.youtube.com/watch?v=wAm4yUo7pgM

This is what I have found. 

IC-92AD production / design flaw. The display sometimes goes blank when a RF field is present. A non-perfect VSWR to the rubber duck antenna will surely induce this upon itself.
Initially reports made it appear that its related to VHF digital mode operation, but it will likely show that to do it more often, and in just FM and UHF operations.

This problem was first observed by some IC92AD users in Dec 2008. When Icom sales and other reps were asked about it at Dayton (May) 2009, there was still the standard "were not familiar with this problem.. and cannot reproduce it."

Sweeping with another VHF HT in transmit perpendicular seems to be the best way to identify if your IC-92AD is vulnerable to this RF shielding flaw.

[KB3LOF]

Same Problem Here, had it for months...too lazy contact Icom..but will tomorrow. Screen inverted with a carrier. Will let you know what they say. Does reset with power cycle. KB3LOF

[G4SPZ]

I must be lucky.  My IC-92D is three months old and does not display this fault 

Phil G4SPZ