[ICOM] IC-756PROIII No Transmit

Phil Krichbaum vailphil at sopris.net
Fri Jul 17 13:09:56 EDT 2009 

Joe,
    Thanks for the info. I agree with ESD protection not being built in 
today's radios even though the components may be more sensitive to it. I 
think some old rigs had a NE2 from the RX antenna terminal to ground.
    Phil N0KE

Joe Oski wrote:
> 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
>>> 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/
>> 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/
> 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/
> To support QSL/QTH.net: http://www.qsl.net/donate.html
>
>

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