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Author Topic: Remove MARS mod from my Icom IC-728  (Read 23166 times)
K7LN
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Posts: 10




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« on: February 17, 2010, 08:45:27 AM »

Recently, I purchased an Icom 728. The unit seems to work ok, But it transmitted on all frequencies. The common modification was to cut D5 on the PLL board to expand HF Tx operation. My rig had this modification, and I repaired it. After resetting the CPU, I found that I can still transmit outside of the ham bands. In most cases it's 600KHz total as in 6900 to 7500KHz.

I'd like to restore the rig to it's original state. Icom tech support won't give me any info. I assume that there's a more detailed modification than cutting D5 to achieve what I'm assuming is a MARS modification.

I originally posted this in the ELMERS forum, but didn't receive any helpful info, so I'll try here.

If anyone has any leads for me to try, please post them or contact me with the info. TNX
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K0CBA
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Posts: 295




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« Reply #1 on: February 17, 2010, 10:03:36 AM »

I am pretty sure that is  the way it is designed as this usually allows true M.A.R.S. coverage because their frequencies are just a whisker above and below the ham bands.

What is the tounge-in-cheek "MARS mod" is to allow transmitting everywhere.

I don't know why hams feel the need to do this but it's the same with 'walkie-squawkies'...never know when some big earth endangering emergency will hit that will require out of band transmissions to save the planet.
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K1DA
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Posts: 474




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« Reply #2 on: February 18, 2010, 03:01:11 PM »

My 728 needs the "Mars Mod" to work on 60 meters.  
Why should anyone give that up?
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K8IZ
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Posts: 17




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« Reply #3 on: March 24, 2010, 08:11:30 AM »

With D5 restored its normal for the IC-728 to transmit beyond the amateur bands a bit. What you found on 40 meters is reasonable. Most of the new Icoms have band edge beeps, actually those beeps occured at the points where the transceiver would no longer transmit.
Some the very recent models have adjustable band edge beeps. You actually adjust those signals to the desired frequency, So you can actually set it up to remind you if you are tuning out of band. I am unsure iof the transmitter was inhibited if you set the band edge beeps up for General Class and you tuned beyond though.

Gary K8IZ
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KE7ZIC
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« Reply #4 on: October 18, 2010, 02:47:19 PM »

fyi, one reason to modify would be if an amateur had a legitimate reason to communicate directly with Law Enforcement and/or Fire units which are outside of the Amateur bands.  For example, Search and Rescue units typically operate on 155.160 so any Ham who is also a SAR responder would need both.  Of course, I have not modified any of my radios...  Wink
cheers...
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AA4PB
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Posts: 12701




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« Reply #5 on: October 18, 2010, 03:54:02 PM »

Transmitting on those frequencies with a radio that is not certified for those frequencies is not legal, regardless of who is doing it. The only exception is if life or property is in immediate danger and there is no other means of communication.

A ham who is also a SAR responder must carry both radios, unless the radio certified for SAR also covers the ham bands.
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W3LK
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« Reply #6 on: October 18, 2010, 05:40:20 PM »

fyi, one reason to modify would be if an amateur had a legitimate reason to communicate directly with Law Enforcement and/or Fire units which are outside of the Amateur bands.  For example, Search and Rescue units typically operate on 155.160 so any Ham who is also a SAR responder would need both.  Of course, I have not modified any of my radios...  Wink
cheers...

Totally illegal to use modified ham gear on ANY frequency except MARS - and you need a MARS-issued license to do that. If the FCC catches you, you'll not only get fined, you'll lose your amateur license. And if any agency knowing allows its member to use modified ham equipment on their frequencies, the FCC will fine the agency AND cancel THEIR licenses.

I'd love to know where Techs get the idea they can use ham gear anywhere they want? 95 percent of comments like ZIC's come from Tech-class licensees.

To add to PB's comment: "The only exception is if life or property is in immediate danger and there is no other means of communication."

This is true, but there is nothing in the rules to keep the agency you talked to under those circumstances from prosecuting you for illegally transmitting on their frequencies. It has happened more than once.
« Last Edit: October 18, 2010, 05:42:53 PM by Lon Kinley » Logged

A smoking section in a restaurant makes as much sense as a peeing section in a swimming pool.
K4RVN
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Posts: 758




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« Reply #7 on: October 19, 2010, 05:32:37 PM »

K7LN
Looks like you struck out again for an answer to your question.
Sorry I can't help.

Frank
K4RVN
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AA4PB
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« Reply #8 on: October 20, 2010, 05:29:24 AM »

"This is true, but there is nothing in the rules to keep the agency you talked to under those circumstances from prosecuting you for illegally transmitting on their frequencies. It has happened more than once."

The agency prosecuted and won a judgment against a ham for using their frequency to save lives when that was the only communications available?Huh I would think that would be very hard for them to win in a jury trial. The ham must have had a very poor lawyer.  Grin

I wonder if they would also prosecute a citizen for using a downed officer's HT to contract the dispatcher and get him an ambulance. I wonder what they would have done if he had left the scene to drive 20 miles to use a pay phone and the officer died while he was gone.

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W6RMK
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Posts: 649




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« Reply #9 on: October 20, 2010, 06:15:46 AM »

one might also modify one's radio to generate RF power out of band if you're using it in a situation where you don't radiate significant amounts of power: e.g. you were doing high power testing of a filter.  One might also have a Part 5 (experimental) license.

The rules tend to be against marketing, sale and distribution and/or use not in conformance with the license.  The former to discourage the latter.

I'd be interested to see any documented case where someone was prosecuted for use of uncertificated gear in an emergency situation.  One might get a "notice" from the FCC (probably a NOUO), but once you've responded with what went on, I suspect that it would stop there and never get to a NAL or criminal prosecution.  I think that's what's called an "affirmative defense"
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W3LK
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« Reply #10 on: October 20, 2010, 08:24:24 AM »


I wonder if they would also prosecute a citizen for using a downed officer's HT to contract the dispatcher and get him an ambulance. I wonder what they would have done if he had left the scene to drive 20 miles to use a pay phone and the officer died while he was gone.



Bob, that is such a silly comparison. Using a downed officer's radio to call in such an event is now where near in the same category as using a modified ham HT to talk to some SAR group or volunteer fire department. The overwhelming majority of the posts asking about doing such things are by SAR members and volunteer firemen who are too cheap to use the proper equipment. That they might never get caught is beside the point; such operation is still illegal.

I guess I operate on a different level from many hams. I operate within the rules and don't try to find ways to justify (in my own mind) violating them when obeying them is inconvenient.  Same idea as obeying the speed limit, stopping completely at stop signs, stopping first before turning right on a red light and so forth.

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A smoking section in a restaurant makes as much sense as a peeing section in a swimming pool.
AA4PB
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Posts: 12701




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« Reply #11 on: October 20, 2010, 11:03:10 AM »

Now I never said that it was OK to use a modified ham HT on SAR frequencies in order to avoid carrying two radios. What I said (which is very clear in Part 97) is that you could use the modified HT in a life and death emergency if it were the only means available. Personally, I doubt that the risk of some local PD successfully prosecuting you for doing it when the FCC permits it is slim to none. That was my point. Don't give new people the impression that it is never legal under any circumstances, because the FCC does make some very limited allowances.

In regard to the "downed officer" I was just wondering if a dept. that would prosecute you for using their frequency to save a civilian life would also prosecute you for using their frequency to save an officer's life. If you look at it that way, its not so much different.

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W3LK
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Posts: 5644




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« Reply #12 on: October 21, 2010, 04:05:31 PM »

We see things differently, I guess.
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A smoking section in a restaurant makes as much sense as a peeing section in a swimming pool.
W8NSI
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Posts: 21


WWW

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« Reply #13 on: June 19, 2011, 08:37:26 AM »

K7LN
Looks like you struck out again for an answer to your question.
Sorry I can't help.

Frank
K4RVN


Isn't it interesting how a simple question of restoring a radio to factory condition descends into a peeing match over legalities of usage off the ham bands? Some people like to hijack a discussion to show how erudite and learned they are (NOT).  Roll Eyes  Grin

A quick look through posts following the question shows that this topic has drifted to another hemisphere from the original question.

Short answer to original question: It is completely normal for a radio to cover a few khz above and below the bands, not a defect. Once you removed the mod, you now have a stock radio.
« Last Edit: June 19, 2011, 08:39:30 AM by W8NSI » Logged

73 de w8nsi/nnn0uzw jim
K6PVA
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Posts: 1




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« Reply #14 on: May 06, 2012, 07:22:21 AM »


I wonder if they would also prosecute a citizen for using a downed officer's HT to contract the dispatcher and get him an ambulance. I wonder what they would have done if he had left the scene to drive 20 miles to use a pay phone and the officer died while he was gone.


[/quote]

I am sure that in an emergency you can transmit on any band or sub band that you need to in order to resolve the threat to life or property. 

Hope that helps.

K6PVA
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