HAM radio with mars cap mod

suicideking

suicideking

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I have a friend looking to buy a ham radio that is already modded to also handle GMRS. Please advise if you know of someone that sells radios that are already modded. Or if you know someone that will mod a radio to do this.
 
I don't know the names offhand but there are at least a couple of radio retailers that will mod a radio that is bought from them.
 
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https://myoffroadradio.com/shop/mars-mod/


And now the disclaimer...
MARS modifications enable out-of-band transmit capabilities on the subject radio. If you are an authorized MARS-affiliated operator, and utilize the expanded transmit capabilities per that authorization in the course of performing MARS activations, you are fine. If you are not, and transmit out of the amateur bands (such as licensed by rule like FRS/GMRS and type certification like Part 90 for Land Mobile Radio), you are in violation of the FCC rule…

Let friend know not to broadcast that he's using a modded radio over the airways.
 
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Akitadog said:
https://myoffroadradio.com/shop/mars-mod/


And now the disclaimer...
MARS modifications enable out-of-band transmit capabilities on the subject radio. If you are an authorized MARS-affiliated operator, and utilize the expanded transmit capabilities per that authorization in the course of performing MARS activations, you are fine. If you are not, and transmit out of the amateur bands (such as licensed by rule like FRS/GMRS and type certification like Part 90 for Land Mobile Radio), you are in violation of the FCC rule…

Let friend know not to broadcast that he's using a modded radio over the airways.
Click to expand...

Perfect, thanks!
 
It's extremely simple to MARS mod most modern ham radios, for example in the Icom 5100, its a matter of simply removing one of the surface mount resistors - you don't even need a soldering iron if you are good with a pair of snips. I think Ham Radio Outlet offers a MARS mod for a small fee, as much as I love those guys, save yourself $20 and go watch a YT video on it, it's not hard.

It is "illegal" to transmit part 90 or GMRS/FRS on a non certified device. That being said, if you follow all of the power rules and do your best to comply with the spirit of the law - it's generally not enforced. I know lots of people that run ham radios on GMRS, simply because they don't want another radio in the Jeep. so while its not technically allowed - its a stupid rule and if you are licensed for both and stay within the power limits of GMRS rules, no one generally minds,
 
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This radio will transmit GMRS frequencies out of the box. I mounted one in my Sprinter because I didn't want multiple radios. Works fine.

1688219437612.png

BTECH UV-50X2


https://www.amazon.com/dp/B06XK83VRV/?tag=wranglerorg-20
 
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I've moded several ham transceivers HF and VHF/UHF for MARS/CAP and they're not always that easy to perform. Two of them required that an extremely small surface mount diode be removed and I nearly needed a microscope to even see the diode. I needed my most powerful jeweler's magnifying lens and a small dental pick and even with them I was skirting with catastrophe. I was sweating when I completed my last two.

So if you're not used to working on modern circuit boards with surface mount technology you'd probably be better off having the retailer do it.
 
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I did the mod in my Kenwood TM-V71a which was a very popular radio (out of production) so there are plenty of tutorials. There are several online tutorials that detail the prices. I found it very easy to complete but like Jerry a due to the size of the component I was little nervous about screwing up the radio. Long story short it works.

Ham Radio outlet is local to me so I can eyeball a radio before buying it will let you add the mod as at an additional cost. However, if standalone GMRS that you are looking for, this is not the place to go.

I think the trick is finding a good antenna that will cover all the bases at least well enough to avoid any radio damage. I have not been able to find an antenna that is a good compromise across the 2m, 70cm and FRS/GMRS. I read good things about a Comet 2x4SR antenna and tried that. I checked the SWR across all three bands. If I remember correctly, the 2m and 440mhz bands were in the 1.2ish range but the FRS/GMRS band spiked into the 3+ range. I don’t think there is an issue with my mount (Teraflex mount in drivers tail light and Breedlove NMO base). I lost interest in the project a while back before getting the antenna properly tuned or finding one that will work for my situation.

Any thoughts on antenna?
 
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I am using a Nagoya NMO-72 19.25" Antenna NMO Mount Dual Band VHF, UHF (145/440Mhz) antenna with my B-Tech UV-50X2 2m/70cm/GMRS radio that I use in my Sprinter van. It works just fine for 2m and 70cm, also the GMRS frequencies. The match for the GMRS frequencies isn't perfect, but more than acceptable.

Another option would be the Pulse Larsen NMO 2/70SH, similar in length. I run one on my Jeep with my Kenwood radio. I tried it with the B-Tech radio and it provides similar performance as the Nagoya.


https://www.amazon.com/gp/product/B0744QPSG8/?tag=wranglerorg-20
https://www.hamradio.com/detail.cfm?pid=H0-000567
 
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Stinkbug said:
I did the mod in my Kenwood TM-V71a which was a very popular radio (out of production) so there are plenty of tutorials. There are several online tutorials that detail the prices. I found it very easy to complete but like Jerry a due to the size of the component I was little nervous about screwing up the radio. Long story short it works.

Ham Radio outlet is local to me so I can eyeball a radio before buying it will let you add the mod as at an additional cost. However, if standalone GMRS that you are looking for, this is not the place to go.

I think the trick is finding a good antenna that will cover all the bases at least well enough to avoid any radio damage. I have not been able to find an antenna that is a good compromise across the 2m, 70cm and FRS/GMRS. I read good things about a Comet 2x4SR antenna and tried that. I checked the SWR across all three bands. If I remember correctly, the 2m and 440mhz bands were in the 1.2ish range but the FRS/GMRS band spiked into the 3+ range. I don’t think there is an issue with my mount (Teraflex mount in drivers tail light and Breedlove NMO base). I lost interest in the project a while back before getting the antenna properly tuned or finding one that will work for my situation.

Any thoughts on antenna?
Click to expand...

Comet SBB-7,NMO its a very large hi-gain antenna, but it's absolutely fabulous and takes a beating.
 
Crom said:
Good SWR across 2M, 440, and GMRS
https://www.amazon.com/dp/B01F446BYU/?tag=wranglerorg-20You may have to modify the bracket that holds the antenna. Be sure you have good metal-to-metal contact for the ground plane/circuit

Use this to analyze SWR across all radio bands
https://www.amazon.com/gp/product/B08H4NFZZ2/?tag=wranglerorg-20https://www.amazon.com/gp/product/B06XPDWBPR/?tag=wranglerorg-20https://www.amazon.com/gp/product/B083WDV529/?tag=wranglerorg-20
Click to expand...

I use this antenna on my Retevis HAM radio, on a magnet mount. Great SWR across both bands, including GMRS frequencies. Here's the odd thing. When I plugged my Midland GMRS xcvr into this antenna, the SWR was atrocious! However, the Midland was just fine with the little unity gain antenna that came with it. As I now need to replace that antenna, I'm a bit flummoxed as to what was really going on - why was the Midland's SWR so bad with the Diamond? Makes me think the Midland radio isn't really 50 ohms - and neither is the Midland antenna, so they play well together but not with someone else's antenna. *shrug* I dunno!
 
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