ICOM 706MK11G

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ICOM 706MK11G

Postby T2tim » Wed Apr 20, 2016 8:04 am

I recently purchased an Icom 706 mk11G from another Ham. its in immaculate condition and the seller seemed to have quite a bit of knowledge about this line of transceivers since it was first introduced as the mark one. he mentioned the radio originally came from Martin Lynch who widebanded it at his request. however, he did warn me about transmitting on 11 metres, which he said he did himself on a regular basis, even if he didnt say what radio he used to do this with. it did surprise me that any Ham would take this risk, and iam not sure its a risk I would choose to take myself. anyway he claimed that transmitting on any of the CB bands would cause damage to the radios filters, especially on high power. he said this would lead to a dramatic loss in power, and even cause untold damage to the PA transistors. he also went on to say, this was especially risky at the lower end of the 26mhz region, where some of the illegal 'freeband' blocks are. (26.065 and above which isnt a million miles away from 12m anyway 24.89-24.99) he said if I must use 11m, then to reduce the RF power to a very low setting, perhaps 10 watts or even less. instead he recommended buying a CB 'burner' if I wanted to use high power on the 11m band, rather than using the 706's amp. now to be perfectly honest I wouldnt want to risk my new licence using a HF radio on 11 metres in any case, but iam very curious about his warning. why? I know the 706 is very popular with freebanders, and ive never once heard any complaints about using the radio on 11m, and certainly nothing related to the issue he described to me. ironically he said he had used the radio on the vhf marine band, and although he claimed to also have a ships radio license, it doesnt alter the fact that the marine band is over 10mhz away from the nearest ham band which is 2m. in comparison, the nearest ham band to CB is of course 10m, but thats very close to 11m. does this mean the 706 is far more tolerant to transmitting out of band on vhf than on hf? because that doesnt sound very logical to me, cos surely transmitting on the marine band could also cause simular damage to the filters? if not more severe because this band is much farther outside of the radios default TX coverage. he told me Martin Lynch told him this story, but after attempting to research this topic online, and after a lot of digging around, I only came across one single website that mentioned this issue, and that was being discussed in a forum. if it was indeed a common problem, you would expect to find the web littered with complaints, especially when so many freebanders use the radio. where hams are concerned, I see nothing but praise for the MK11G, although there were a few complaints about the mark one which you would expect, although non were related to RF power. is it possible Martin Lynch told the seller this as a scare mongering tactic in order to discourage the use of 11m?! after all they may have had a low opinion of a Ham using the radio for 11m DX. I know a few freebanders myself who use this radio, and ive also spoken to a local ham I know who has had many 706's in the past, and they all said they had never heard of this problem with the 706. but if it is true could the same thing also effect other widebanded HF radios? regardless of which band they intend to use outside the Ham bands. or is this unique to the 706? I remain sceptical about this for the reasons I have already made clear, but I would welcome any input on this topic if anybody knows better than me????? by the way the seller did show me his ham license.
Last edited by T2tim on Wed Apr 20, 2016 8:28 am, edited 1 time in total.
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Re: ICOM 706MK11G

Postby Mick M5AED » Wed Apr 20, 2016 8:24 am

Lets ignore all the strange technical talk ! I wonder how wise it is for this forum to allow any coverage to illegal activity. The forum should act in a responsible fashion and I would not like to see it jumped on by the authorities.
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Re: ICOM 706MK11G

Postby T2tim » Wed Apr 20, 2016 8:32 am

The only thing iam concerned about is that there maybe a problem with the output on the radio ive just bought, 11m doesnt concern me because I no longer use it. However, I do see your point regarding the legal implications, and also wouldnt like to see this forum jumped upon. But that would also involve scanner users who work against the wireless telegraphy act every day! After all its even illegal to listen to the Civil Aviation band, even if its tolerated.
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Re: ICOM 706MK11G

Postby m0lsx » Wed Apr 20, 2016 5:45 pm

There is plenty of information around about both Icom's & Yaesu radios blowing their finals
Blowing the finals on a radio by using it out of band on full or high power is not limited to use on CB. It will also sometimes happen on a VHF amateur radios on used on marine band or on a UHF radio used on 446.
I know in the past I have heard regular Marine Mobile (/MM) operators talking about some VHF amateur radios being very fragile on marine band. VHF amateur radio sets do make a very good only in an emergency back up radio & blown finals are not a massive loss if the radio saves your life. But radios use different components & some really do not like out of band operations, whilst others are less fragile.
I assume you saw your radio loaded into a dummy load before you brought it?? If the power output was still 100 watts, then all is fine.
If you look at a list of the radios that will operate on 4 meters, (70mhz,) you will find several radios that can be opened up for it. Now look at their power output on 4 meters for those opened up radios & you will see that they run at massively below their specified VHF power output, that is because the radio is not happy with what it is being asked to do.
Over voltage, especially during high power FM use can be a real killer, which is one reason why radios used on CB are more prone to damage than any other HF use. Plus FM is a much higher duty cycle than the more normal SSB or CW & no one with any brains runs other high duty cycle modes at high power & here I am thinking of Digi modes on HF, where 25 watts or less are the norm.
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Re: ICOM 706MK11G

Postby Mick M5AED » Wed Apr 20, 2016 6:20 pm

T2tim wrote:The only thing iam concerned about is that there maybe a problem with the output on the radio ive just bought, 11m doesnt concern me because I no longer use it. However, I do see your point regarding the legal implications, and also wouldnt like to see this forum jumped upon. But that would also involve scanner users who work against the wireless telegraphy act every day! After all its even illegal to listen to the Civil Aviation band, even if its tolerated.

The authorities tolerate scanner users as they are only listening, transmitting is a very different matter that may carry a serious punishment !! A transmitter in the wrong hands could cause problems to other service users, perhaps even being a risk to life.
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Re: ICOM 706MK11G

Postby m0lsx » Wed Apr 20, 2016 7:14 pm

Mick M5AED wrote: Transmitting is a very different matter that may carry a serious punishment !! A transmitter in the wrong hands could cause problems to other service users, perhaps even being a risk to life.


Two recent cases prove that. One in Cambridge where someone was jamming, or apparently trying to jam helicopters going in & out, just after it was announced that William was flying for the air ambulance & the second up in Edinburgh, I believe it was, where again someone was deliberately trying to jam legal users.
Also last year I know there was a case involving an idiot his local prison frequency. It was reported & discussed at the time, but suddenly news references to it disappeared.
But the biggest issue with modified radios is there lack of band pass filtering, which means harmonics causing interference is a much bigger potential, especially given the way some fools over drive their radios.
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Re: ICOM 706MK11G

Postby T2tim » Thu Apr 21, 2016 2:54 am

MO1SX: when I contacted the seller I explained I no longer had any test equipment and therefore asked to see the radio transmitting through a dummy load on a meter. When I arrived he did have it rigged up to a dummy load but no watt meter! All I witnessed was the power being turned up down on the radios meter which was disappointing, but I took the radio hoping it was ok because it was a 100 mile journey. If he hadnt mentioned out of band transmitting I wouldnt have doubted him because he seemed very genuine, but I will admit its now worrying me a bit. I think iam going to have to either get it checked out in a radio shop, or find someone thats willing to check it for me within reasonable travelling distance. I woud even be willing to pay someone to do this for me if anyone is within 50 miles of Banbury Oxfordshire? Just to put my mind at rest. Iam starting to think I should have walked away, a bit of a risk to take. That said, he did give me the impression he looked after his stuff, and he showed me other radios he covered when not in use to protect them from dust.
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Re: ICOM 706MK11G

Postby Mick M5AED » Thu Apr 21, 2016 9:32 am

Unable to understand what you want now. Do you have an amateur license, if so then why are you concerned about using it on a cb ?
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Re: ICOM 706MK11G

Postby m0lsx » Thu Apr 21, 2016 10:12 am

T2tim wrote:MO1SX: when I contacted the seller I explained I no longer had any test equipment and therefore asked to see the radio transmitting through a dummy load on a meter. When I arrived he did have it rigged up to a dummy load but no watt meter!


If he had several radios & a dummy load, then it seems very strange he did not also have a SWR meter that showed watts. What is the point of a dummy load if you have no test kit?? A £30 cross needle is all that is needed too see what is happening with watts out.
If prior to going to see the radio, you asked to see it running into a dummy load, then why not walk out, if he left it until you were there to say.."Oh I can't"?? As anyone who has even the most basic level of understanding, would know that is the most basic need to know when buying a radio. So it does not sound good at all that he did not tell you he could not show you the power output until you arrived.
A 100 mile journey is better as wasted petrol, than as a 100 mile journey, plus a duff radio.
It also feels very odd to me, that if you went there as a radio amateur, rather than as a CB'er, that he then mentioned using that radio on CB & even odder that he would tell you that what he has done could damage the radio you are about to buy.
Did you check him out in any way before agreeing to travel 100 miles?? And why travel all that way?? I am surprised that your area does not have a ready supply of decent radios available. Oxfordshire is not remote or sparsely populated.
Personally if I arrived at someone's to buy a radio & they could not show me the power output, I would walk away & the same if they mentioned using the radio on CB. FM is a higher duty mode & it thus produces more heat in components & they thus fail quicker.
It all feels very odd.
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Re: ICOM 706MK11G

Postby Mick M5AED » Thu Apr 21, 2016 12:33 pm

Mick M5AED wrote:Unable to understand what you want now. Do you have an amateur license, if so then why are you concerned about using it on a cb ?


That should say "using the radio on cb", not "on a cb" !
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