[ICOM] IC-756PROIII No Transmit

Joe Oski jen1joeo at yahoo.com
Fri Jul 17 12:33:01 EDT 2009 

My NM shack has several antennas. Except for the 480 Ft horiz loop, ALL are designed to be DC grounded. This design discharges the static voltage build up before it accumulates.
 
I suggest retrofitting your shack with RF Chokes in parallel with each antenna cable.
Ameritron sells a RFC used in KW class Amplifiers for about $8.
The RFC has about 25 Ohms of DC Resistance and
at HF it has a VERY high RF Impedance.
 
If you have non-resonant antennas, (impedance varies widely) try a 
200 KOhm non-inductive resistor across the antenna line. 
This cured ATU diode burnout when connected to a  160 Ft Inverted L antenna.
 
In my opinion, ESD protection is NOT a built in feature in today's radios.
 
My primary HF rig is the Pro3, VHF is the 746.
 
73
Joe Ostrowski, KI5FJ
In the New Mexico desert.
 
NNNN


--- On Fri, 7/17/09, Phil Krichbaum <vailphil at sopris.net> wrote:


From: Phil Krichbaum <vailphil at sopris.net>
Subject: Re: [ICOM] IC-756PROIII No Transmit
To: "ICOM Reflector" <icom at mailman.qth.net>
Cc: ICOM756ProIII at yahoogroups.com
Date: Friday, July 17, 2009, 3:24 PM



    I'm just getting ready to ship my PROIII in after the fifth time for 
this ESD failure. I guess either I'm a slow learner or the 756 series is 
overly sensitive to ESD. I might add I live in western Colorado at 6000 
ft on a high spot in the middle of a large valley surrounded by peaks to 
10,000 and over. Colorado is 2nd to Florida in the number of lightening 
strikes yearly and out west we only get them in the summer. The majority 
of strikes are in the flat eastern part of the state but we still get 
our share in the summer in the western part of the state.
          I also have a FT1000MP that I've had much longer than the 
PROII and PROIII combined and it has been connected to the same antennas 
for many more hours than the Icom PRO II and III rigs without ever 
having one problem. My PROII was destroyed when a near strike came in 
the neutral side of the AC line. That was the first and last problem 
with that rig. I had no coax connected to anything in the shack. The 
PROII was off but the Icom supplied PS was left in the ON position. The 
PS survived! There were signs of damage in the rig where the DC enters 
as well as the CIV cable and CW keying line from the computer. The 
computer HD was destroyed as well as well as a telephone and 27" TV and 
a few other assorted items like an electric garage door opener, well 
control relay and remote temperature sensor on 430 MHz.     When I 
bought the PROIII rig to replace the PROII in August 2007 it failed on 
power out the first time within one hour of when I turned the rig on for 
the first time out of the box and there was no WX issue that evening. I 
used it on 20 CW making 2 short CW QSOs with QRP and after one short QSO 
at 100w. I have an amp but did not have it in line and plugged the coax 
from the TH6DXX direct into the rig. SWR on the TH6DXX was fine. By the 
way Icom billed me around $250 for the repair claiming I operated it in 
a non warranty condition and after a few phone calls I got them to 
accept it as warranty repair. As I look back on it I think I got a lemon 
and the rig should have been replaced at that time!
     I have since added a "Meter Treater" at my power meters which has 
some big mother MOVs in it. Call your local power company about these! I 
also added UPS supplies for the TV, rigs and computer. I discovered that 
Polyphasers need to jump an arc to discharge ESD and I now have some of 
the ICE 303U and 303N 8KW Impulse suppressors on order. I am getting 
ready to move the ham shack and the new shack will have 3 bladed knife 
switches on the AC lines for 120 VAC and 240 VAC so there will be no 
connection from the AC lines to the equipment once these are thrown upon 
exiting the shack. I'll probably have to put a red light by the door 
that I'll see as I exit the house if it has been left on. Apparently 
lots of lightening damage comes in the neutral side of the AC lines.
    I also have some RX antennas but bring them into the rigs thru one 
of KD9SV's DXpedition II switch boxes that switches 4 RX antennas and 
has a variable gain preamp for 80/160 and brings the RX antennas in thru 
the TX SO239. If you use the RX antenna terminals on many rigs (MP and 
PROII and III from my understanding among others), the RX antenna is not 
disconnected from the RX when you TX! This seems to be a rather serious 
oversight!
    I love the PROIII receiver (except for the dual watch deal) but may 
move on to something else that has less ESD sensitivity. I'm going to 
send it in again but may sell it after it is repaired for the 5th time. 
It has never been the drivers or finals, just FETs and diodes, mostly in 
the tuner. I wonder if these problems still exist in the 7600?
    73 Phil N0KE

Alan Zack wrote:
> My 756ProIII is back at the Icom America Bellevue Service Center for the 
> second time. This rig was purchased in November 2008 and should still be 
> in warranty.
> It was returned to ICOM in March 2009 for no transmit, no power out in 
> any mode. ICOM replaced the following parts. They only list the part 
> numbers, not the actual devices so I can't be sure what exactly was 
> replaced. There were no notes, no repair description or phone calls 
> about the problem, it just turned up when a FedEx driver rang my door 
> bell. Part numbers are 1110006430, 1750000581, 1750000851,and 
> 1530003091. I was later told they are the T/R switching diodes on the 
> control board.
>
> Now it is back at ICOM for a different problem. The rig was on, I saw a 
> spot for someone I wanted to call, and when I keyed the mic (SSB) I had 
> a steady carrier at more than the normal 100 watts output. I tried all 
> bands and modes. With no CW key or mic connected, no matter what 
> mode/band was selected, the rig put out a 100 watt plus carrier. I am 
> assuming it is some sort of harmonic oscillation.
>
> I received a call from Icom asking how I wished to pay $213.00 for the 
> current repairs. I told them it should be under warranty but was told 
> the failure was caused by ESD and not covered by the warranty. They said 
> they would get back to me.
>
> I only have one antenna connection to the rig from a LDG model DTS-4 
> antenna switch. There is a Force 12 beam at 55 ft, a sloper, and a 
> vertical connected to the DTS-4. When I shut off the rig I also set the 
> DTS-4 to GROUND ALL which grounds the antenna jacks. I also turn off the 
> power supply. I have PolyPhaser coaxial protectors on all coaxes where 
> they enter the house, grounded to a ground rod professionally installed 
> by the company that installed my tower. With all my antennas grounded 
> and the P.S. turned off how would I get ESD to the rig? Also, ESD to me 
> is what happens to your receiver front end. The receiver worked FB on 
> both failures, it was the transmit function that failed with two 
> separate problems. I live in Las Vegas. We don't have rain or 
> thunderstorms here. I do realize there can be static in the air, that's 
> why the USCG C-130's I flew in and worked on had static discharge wicks 
> on the trailing edge of the wings but I don't think I have that kind of 
> static in the air to effect a stationary antenna at 55 ft. There are no 
> transverters, CVI devices, etc, connected to the rig.
>
> I have now received a return call from the Icom tech who is doing the 
> repairs. The first phone I received was from the billing department and 
> they were not able to provide me with the technical reasons why they 
> believe my failure is due to ESD and not covered by warranty. I am told 
> that is again the same T/R switching diodes on the control board that 
> failed supposedly from ESD. It seems I better check the grounding 
> operation of my DTS-4 ant switching box and outside ground connections. 
> I was told that just disconnecting the ant from the rig is not good 
> enough, that the static charge can stay in the coax (capacitor effect) 
> and then you reconnect the coax to the rig you will destroy these 
> diodes. The coax must be grounded while disconnected. The Icom tech 
> tells me he sees a lot of these failures from dry states such as mine, 
> NV, as well as AZ, NM, UT, etc. where there can be dry static in the air 
> without a storm. So what are you supposed to do? I am a contester. I 
> can't have my ant coax grounded while I am in a 48 hour contest. If Icom 
> is seeing these T/R diode failures even when there are no thunderstorms 
> then I think they should do something to better protect them.
>
> BTW, I used a IC-746 (non PRO) for years and years and never had a 
> problem. I am now using the IC-746 as my back up rig while the 756 is at 
> Icom with no problems.
>
> _______________________________________________________
> Alan Zack
> Amateur Radio Station K7ACZ
> Official USCG Auxiliary Comm Station
> Las Vegas, Nevada, USA
> Delta Rocket Quality Engineer, The Boeing Company, Retired
> Aviation Chief Warrant Officer,  U.S. Coast Guard, Retired
> ---------------------------------------------------------------------
>
> ----- Original Message ----- 
> From: <k0bx at arrl.net>
> To: "ICOM Reflector" <icom at mailman.qth.net>
> Sent: Tuesday, March 24, 2009 12:40 PM
> Subject: [ICOM] IC-756PROIII No Transmit
>
>
>   
>> Larry, thank you for your comments.  I do agree with what you said.
>>
>> But in my case, I do not have any other antenna connected.  The 1st 
>> time was on 20 CW using my Hygain 204BA 4 element monobander with no 
>> amp.  I agree that some RF must be getting back to the rig somehow, 
>> but I do have grounding devices on all my antennas.
>>
>> The 2nd time, I just (Like the other guy) just turned on the rig to 
>> find it dead on transmit.  I know that sounds like an e-bay thing, "It 
>> worked the last time I used it".
>>
>> One of the gentlemen in my DX Club got rig of his PROIII after 3 
>> repairs for the samething.
>>
>> I have used a TS-850S on this antenna for 12 years and when taken out 
>> of service it performed on transmit like the day it was brought.  My 
>> IC-706MK2G have been on this antenna for the last 5 years.  No 
>> problems with them.
>>
>> As far as the Burghardt BEV-756, Burghardt recommended it as a 
>> solution to my problem even though I do not use a Bev Antenna.
>>
>> It seems that others are having the same problem and only using one 
>> antenna at a time.
>>
>> Joe K0BX
>>
>>
>> Stop the insanity!
>> Please do not add me to any distribution lists (Joke, Stories or Junk) 
>> without my permission.
>>
>>
>> --- On Tue, 3/24/09, Lawrence Young <k4lxv at bellsouth.net> wrote:
>>
>>     
>>> From: Lawrence Young <k4lxv at bellsouth.net>
>>> Subject: Re: [ICOM] IC-756PROIII No Transmit
>>> To: "ICOM Reflector" <icom at mailman.qth.net>
>>> Date: Tuesday, March 24, 2009, 9:03 AM
>>> Guys: Products like the Burghardt BEV-756 are designed to
>>> serve as a front end saver for those hams who may not
>>> understand that one cannot safely transmit on one antenna
>>> and leave another one such as a Beverage receive antenna
>>> still connected to the receiver. I am amazed at the number
>>> of hams that I know who may do this without realizing the
>>> possibility of damage to the radio.
>>> Larry K4LXV
>>>
>>>       
>> ----
>> Your Moderator: Dick Flanagan K7VC: icom-owner at mailman.qth.net
>> Icom Users Net: Sundays, 1700Z, 14.316 MHz
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>>
>>     
>
> ----
> Your Moderator: Dick Flanagan K7VC: icom-owner at mailman.qth.net
> Icom Users Net: Sundays, 1700Z, 14.316 MHz
> Icom FAQ: http://www.qsl.net/icom/
> To support QSL/QTH.net: http://www.qsl.net/donate.html
>
>   
----
Your Moderator: Dick Flanagan K7VC: icom-owner at mailman.qth.net
Icom Users Net: Sundays, 1700Z, 14.316 MHz
Icom FAQ: http://www.qsl.net/icom/
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