Discuss Vehicle Based GMRS/FRS Radios and Antenna Set Ups.

DaveInDenver

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Those 32" antennas are 5/8 wavelength stacked elements. What it looks like mounted with no ground plane. Main lobe occurs at 47°.


stacked58gmrs_freespace.png

Same over a ideal ground, pattern more typical if on a roof. Main lobe is 55°.
stacked58gmrs_overgnd.png
 

Hulk

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I bought the MXT275 with the "Ghost" antenna and it works great -- too great, in fact. The antenna does an excellent job picking up conversations father away from other groups who are wheeling and using the same FRS/GMRS channel as the Cruise Moab group that I'm in. I finally got tired of this and switched back to using my handheld FRS radio for running trails at CM.

I'll probably permanent install the MXT275 and the ghost antenna at some point, but for Cruise Moab, the handheld radios work perfectly. They pick up everyone on my trail but not everyone in Moab using the same channel.
 

DaveInDenver

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Did you try just increasing the squelch? On the MXT275 that's adjustable in I think 9 steps and I'd guess based on what I assume is the design that it would actually be pretty effective at selecting for close stations.
 

Hulk

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Did you try just increasing the squelch? On the MXT275 that's adjustable in I think 9 steps and I'd guess based on what I assume is the design that it would actually be pretty effective at selecting for close stations.
I don't remember. I'll have to hook it up and try it again some time. Probably won't mess with it for CM 2023 since the handheld units work sufficiently well.
 

HoneyBadger

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I ordered the 275, it just showed up yesterday. I haven't had a chance to take it out of the box and look at it yet.
Pretty excited to get it installed though.
 

DaveInDenver

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I don't remember. I'll have to hook it up and try it again some time. Probably won't mess with it for CM 2023 since the handheld units work sufficiently well.
Totally get that. It would interesting to experiment later with it to see if each step is significant or not in the radio.

Sometimes each step raises the threshold by 3 or so dB and in that case say setting 1 is right at the normal noise floor (e.g. squelches out background static) and you can hear distant stations at setting 2, a 3 dB increase in squelch threshold per step would make step 9 take about 24 (or so) dB higher signal to open the audio.

That would be as if the transmitting station went from using 15 watts to 0.06 watts (250 times less power) or the path loss equivalent of being 80 km away instead of 5 km, e.g. about 16 times farther away.

But sometimes the squelch step size is set small and it makes almost no difference going from 1 to 9 like this. A test for some future ham and eggs.
 
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HoneyBadger

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Notyourmomslx450

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I just did this with one of those ghost antennas.
Haven’t had a chance to use it yet.
IMG_0486.jpeg
 

stusic

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Totally get that. It would interesting to experiment later with it to see if each step is significant or not in the radio.

Sometimes each step raises the threshold by 3 or so dB and in that case say setting 1 is right at the normal noise floor (e.g. squelches out background static) and you can hear distant stations at setting 2, a 3 dB increase in squelch threshold per step would make step 9 take about 24 (or so) dB higher signal to open the audio.

That would be as if the transmitting station went from using 15 watts to 0.06 watts (250 times less power) or the path loss equivalent of being 80 km away instead of 5 km, e.g. about 16 times farther away.

But sometimes the squelch step size is set small and it makes almost no difference going from 1 to 9 like this. A test for some future ham and eggs.
I have no idea what you said, but I'd sign up for a class where you explain all this. I got my ham license, but only know how to talk on my handy. I'd love to learn how it all ACTUALLY works - antennas, APRS, programming...
 

Johnny Utah

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Didn't we get a Rising Sun member discount at Ham Radio Outlet at some point?

I think you’re right. I believe @Inukshuk was the one that shared it a while back.

I have no idea what you said, but I'd sign up for a class where you explain all this. I got my ham license, but only know how to talk on my handy. I'd love to learn how it all ACTUALLY works - antennas, APRS, programming...

Me too. I don’t know much about gmrs, and ham. I have both licenses so I can push buttons but not much else.
 

stusic

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HRO, or more specifically ‘Jim”, would give new hams from Rising Sun a discount. The deal dried up when Jim retired a few years back.
I think that's what I was remembering. Congrats to him, a shame for us 😜
 
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