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Author Topic: Off frequency RF  (Read 1496 times)
K7MDO
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Posts: 325




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« on: June 19, 2007, 08:12:27 AM »

I have been using a new to me but used IC-718 now for about 6 months and only last night did I notice something about the radio that makes me think there has been a modification to it that could be a bad idea.

I often use WWV to get GMT for my logs right after a QSO and since 10 mHz is the one that always works I go there. Out of habit, I happened to press the "tune" button on the set to bring the AH-4 and long wire into best match at that frequency. What suprised me is that the "tune" function worked, it should not have as it transmits RF when tuning.

That started a hunt for other anomolies and they are apparent though confusing. When reading the manual, there should be a warning beep at each band edge. There seems to only be a beep at the top edge, not the bottom edge.

Any ideas?
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AA4PB
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Posts: 13033




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« Reply #1 on: June 19, 2007, 08:21:19 AM »

Most of the newer radios can be modified to provide transmit outside of the ham bands.
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K7MDO
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Posts: 325




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« Reply #2 on: June 19, 2007, 08:29:38 AM »

I have learned that a modification is possible but in reading about it, it would seem that it would allow the set to transmit anywhere in the 1-30 mHz area... mine definitely does not though I have not mapped the entire spectrum, I have tried a couple of places and been unable to transmit out of band....

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KE3WD
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Posts: 5689




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« Reply #3 on: June 19, 2007, 10:10:08 AM »

If you are the sole owner of the rig from new, try a full reset first.  

Some rigs can be sent out of band via their own software rather than opening the radio and soldering jumpers, although information on how to do that is sometimes sketchy.  Don't count on mfrs to share that info, but if you search the web you can sometimes find out what experimenters have found and published about that.  

Full Reset and do all your testing into a dummy load, just in case.  

"Hey Riley, we found the lid who dumped the carrier on WWV last night...  "   (just kiddin')


.
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KE3WD
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Posts: 5689




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« Reply #4 on: June 19, 2007, 10:16:18 AM »

To further clarify, I've seen some of these rigs get reset via software to situations where they will transmit out of ham bands but do it selectively, possibly a MARS setup table inside the radio's ROM, or another "Service" setting pre-programmed in there -- and the owner did nothing deliberate to make that happen.  

In one case, although it wasn't an Icom radio, the ham happened to be pressing two front panel buttons simultaneously to do an entirely different thing when the power in the neighborhood cycled.  Instant out of band radio was what happened.  

In that particular instance, attempts to do software reset as per the manual did not return the radio to "as shipped" config.  

That is how I found out about the situation the first time, the fellow brought the rig to me and on the test bench, after trying a few pushbutton resets and the like, I opened the radio up and shorted the memory battery out quickly, that did the trick.  HARD reset.  Sometimes even that may not be enough if the radio's memory has a flash function in it.  

Luck,


.
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K7MDO
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Posts: 325




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« Reply #5 on: June 19, 2007, 10:31:08 AM »

I had not thought of the reset function or even the possibility of doing that... no the radio inside had two other call signs penciled in so I am at the very minimum the 3rd owner....

I have added a 500 hz filter but nothing else.  The inside of the radio appeared quite clean and unaltered to the cursory glance.

This weekend if the boss lets me have the time I will do a reset per the manual... see what happens...  thanks for the note on the reset, not sure I would have thought of it...

 
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KE3WD
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« Reply #6 on: June 19, 2007, 12:47:11 PM »

If pre-owned, the most likely mod would be a hardware mod to go out of band.  

The QRZ reference will tell you how to spot that and if you like, "undoing" it is the inverse of doing it.


http://www.qrz.com/download/mods-i-k/ic718_2.jpg



.
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KE3WD
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« Reply #7 on: June 19, 2007, 12:49:10 PM »

Sorry, that was just the pic, here's the text:

http://www.qrz.com/download/mods-i-k/ic718.txt

Looks simple enough:  If D-54 is missing, the mod has been done to the radio.  

Replacing D-54 and then doing the reset if there is one should put it back to Amateur only if that is what you want.  


73,

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ONAIR
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Posts: 1747




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« Reply #8 on: June 20, 2007, 12:03:04 AM »

    Since there are 2 other callsigns penciled in, you might want to look them up and contact them!  They may be able to give you some info. on what might have been done to the radio.
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KB9CRY
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Posts: 4283


WWW

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« Reply #9 on: June 20, 2007, 06:08:06 AM »

Actually redoing the mod would be doing the mod in Reverse not Inverse.  Inverse would be 1 over the mod which would result in I'm not sure what would result.  Do the reverse of the mod instructions.
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K7MDO
Member

Posts: 325




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« Reply #10 on: June 20, 2007, 07:13:39 AM »

I spent an hour last night mapping the "active" transmission frequencies.  Interesting and there is no where in the manual are the band edges identified.  

Transmission a go in the following bands and not in between:

1.8-2.0
3.4-4
6.9-7.5
9.9-10.5
13.9-14.5
17.9-18.5
20.9-21.5
28-30

Clearly some of these range far outside the ham band edges.

I did the RESET and no difference.  I get a BEEP at each edge and inside the reanges listed above I can "tune" and transmit.  Hwoever, outside of the ranges the unit is blocked.

One thing, while I am writing this I wondered is if the unit is somehow not for the US marketS??  I vaguely remember a serial nuber ID on the back of the manual that lists the codes of the serial number for sale in different regions of the planet?

Ideas?

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K7MDO
Member

Posts: 325




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« Reply #11 on: June 20, 2007, 10:22:27 AM »

Well, egg on my face for not doing a search of the forum for any other instance of this "out of Band" capability.... it was a big topic in 2005 and as it turns out Icom and apparently many radios do exactly what mine does and it should be considered normal.

Obviously it is my responsibility to operate within my privileges defined on my amateur radio license and even though the -718 is sold as a "ham" radio the company (Icom) is in no way required to formalize the radio to llimit this operation... or at least that is the thread conclusion in 2005.  

If you are interested further, search this forum for "out of band" and you will find a long thread.

Thanks for other inputs on this issue but for now I believe it is "normal".

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KE3WD
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Posts: 5689




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« Reply #12 on: June 20, 2007, 01:08:55 PM »

>>by KB9CRY on June 20, 2007    

"Actually redoing the mod would be doing the mod in Reverse not Inverse. Inverse would be 1 over the mod which would result in I'm not sure what would result. Do the reverse of the mod instructions."<<


:-)


And thank you for sharing!  


.  
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W5CPT
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Posts: 561




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« Reply #13 on: June 20, 2007, 03:48:46 PM »

I have an original IC-756 and the rig will TX outside many US band edges. As yours, will mine will also TX at 10M (I use an AH-4 to tune a Vertical).

It is your (and my) responsibility to not transmit outside the frequency on which we are allowed. Remember the same rig is bought by Techs, Generals (and some old Advanced like me) as well as Extras.

Clint - W5CPT
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N2HBX
Member

Posts: 162




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« Reply #14 on: June 28, 2007, 01:53:00 PM »

Maybe I missed something, but does anyone recall that we have an allocation in the 10 MHz band (30 Meters)? Why is there so much consternation about the radio  transmitting there?

73,
Larry, N2HBX
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