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And that's what I was talking about as well. Did you not see me mention FM in my post? Go back and read it again in case you missed it. And I also said that I know of three people who are using it in their dump trucks. So, someone (3 people actually) is using it.

Not Radio related but i got myself a 4Bay QNAP and 4 16TB NAS Drives. That should keep me busy for a week.

I guess I can justify my LMr400 cable as a Fathers Day gift (even if I ordered it last week).

Some Repeaters, I.e. my Hytera's, can be set in programing for IP transport basically linking them. Many Commercial repeater radios can also do this.. Although not legal in GMRS many commerical repeaters can be set in this fasshion but requires like systems.

People epoxy sheet metal to the underside of toppers all the time. And that works fine for a ground plane. Having good contact between the NMO mount and a sheet metal ground plane is what matters.

RG8X has around 86% loss over 100 feet while LMR400 has around 48% loss over 100 feet. Plus the fact that the center conductor, insulations (dielectric) and shield braid are bigger with LMR400 which helps reduce loss. @WRDJ205 your real world measurements are close to what most online coax loss calculators will show. While a j pole is not the best antenna, they work just fine. I've seen enough home made UHF j pole antennas built from solid copper wire that works well. No they won't have as much gain as other designs but nothing wrong with a J pole.

I do the same. I was just curious what bandwidth problem he thought we would be out of compliance on

It depends on the agency and what equipment they have available to them. I know that 20-30 years ago, we had equipment in the military that could triangulate a transmitter quickly. Even today's systems such as the Kraken SDR can pinpoint a transmitter fairly quickly, and two or more Krakens in different locations and the time to pinpoint a location goes down. One Kraken will get you pretty close and do so in a reasonable amount of time. 2 Krakens will do it quicker and with more precision. Three or more Krakens will be even more accurate and take less time.

The radios I have with GPS (Hytera) must be turned on in the program mode and programed how you want to xtmt/rcv GPS data. I can set GPS data to specific groups and not to other groups. If you dont have it set to send your GPS data to a specific group, nothihesng is sent, However i can set up in programing to receive GPS data from a certain group. . I have played with this but never really saw a need for it so i ignoree GPS in programing (off).. A local 4-wheeler group uses GPS in their readios to ping their locations when 4 wheeling.. Take note, Radios with GPS need to be 'like' radios as their GPS function are proprietary to the radio brand. My Hytera radios with GPS wont work with Motorola or ICOM and vis versa.

I set duplex to off on 8-14 so I can monitor them but not transmit. Should there be a legitimate reason to do so, I can pretty quickly restore the transmit capability on that frequency. It's hard to imagine a situation where that would be necessary, but I can do it if I need to. I just do all my GMRS communication on the other channels.

I dunno about everyone else, but I do it by selecting 20 kHz or 12.5 kHz when I program the radio, according to what's authorized for the frequency.

You more than likely may have a little Itty bitty wire strand shorting out to one of the connectors. Get a multi-meter and attached a probe to the center conductor and the other probe to the outside of the connector and set the meter for a continuity check and you should have either "OL" or 0.00 ohms for a perfect assembly of the connector(s). If you get any reading other than the aforementioned, you have a short. Or, your antenna is way out-of-band. Check the antenna with an antenna analyzer to determine the frequency center resonance. Who assembled the connectors? Where did you purchase thd LMR400 cable from? My first recommendation is scrap the J Pole and get a real professional grade antenna such as a Laird, Larsen, etc. and tune it accordingly.

Most radios have a physical off switch unlike phones which have electronic on/off switch. No power is no reception/transmission. They could sneak in a bypass resistor to keep the power on for the GPS.

Radios today are basically computers that transmit radio signals. If it has GPS it could store info without the user knowing. And as I posited a radio could include GPS and data storage the owner never knows about. And if so, it may not be possible to disable the GPS. And it would be quite possible to have it on even when the radio is "turned off". At least until the battery died.

so the car wash finally ate my nagoya magnet roof mount and mtxa25. which is wild since its been through several hundred washes. pretty sure an over agressive top roller got it and *yoink* go bye bye so its time to finally do a permeant mount . looking for a thru the roof option and i see two basic solutions https://www.amazon.com/Vehicle-Antenna-Installation-Extension-Kenwood/dp/B077P26SY3/ through mount with attached cable or something like this https://www.amazon.com/Anina-Connector-Assembly-Adapter-Mounting/dp/B0DFLMTLD4/ nmo->SO239 and just use a good quality pl259 cable with like a 90 degree adapter on it? i will be drilling the roof of both my silverado crew cab and a 2013 sonic hatchback and burying the cable under the headliner. am i missing a better option? any experience doing a mount like this - good, bad or indifferent? i do have steel offroad bumpers and could mount there on my truck, but i'd rather go thru the roof to get the antenna height, especially for around town when i dont have my MTXA26 whip on the roof and i'm running the little stubby. just trying to avoid losing *another* $50 antenna and $35 antenna mount, while not having to dismount it off the roof every time i wanna get a carwash also- i do have a fiberglass topper on the bed of the silverado, wouldnt be against mounting on there, but that would mean i'd need a ground plane of some type. i dont want to do a mount with the 3 ground plane stubs coming off it, and know that something as simple as a peice of metal (like even using a baking pan with a magnet mount for outdoor/non vehicle usage) can work as a functional gorund plane. would it be possible to mount said ground plane inside the fiberglass topper and have it functinal? or would it need to be external to be useful? Just making sure i'm not overlooking an easy option that allows me to skip drilling a hole in the cab of my truck if need be. TIA for all your feedback!

Since it’s been a year and I’m still dabbling in GMRS I decided to splurge on 50’ of LMR400 to connect to the J-pole on a stick that I showed previously. It arrived today and I thought it was time to do a test. This is just a relative comparison test. Checking the output of the radio I was getting about 9W as a baseline. I connected the radio to the Surecomm with just a rubber ducky antenna on the antenna side recognizing that this is not a good combination but it was consistent for the testing. Using the RG8X I measured 1.37W at the end of the cable. Next, I did the exact same test with the LMR400 and got 6.07W. I was surprised at the results so I did it again and saw the same. I realize that the LMR400 is a better cable but I did not expect to see such a large difference.

The availability of those repeaters covering multiple frequency pairs is what brought this question up. I was curious why the packaged repeaters were able to cover multiple pairs when the one on BuyTwoWay had to be tuned for a specific frequency pair. It seems like it’s somewhat of a compromise but you get the convenience of a pre-packaged unit. Something to think about.

Thank you for that info. That was already taken into account in my plan.

Which bandwidth requirement are you looking at? GMRS allows 5kHz deviation in channels 1-7 and 15-22, along with repeater inputs. It's not out of line with what 70cm ham radios will emit. Usually where ham radios are problematic is that they often won't transmit as low as 0.5w ERP unless you're transmitting them into a dummy load. So channels 8-14 are often impossible to be in technical compliance on, when using a ham radio.

I think you should revisit your original 1st sentence, "building a briefcase repeater using a couple of HT's" - And further address your future repeater site location, including elevations, antenna gain & total loss, as compared to your current HT user elevations & issues. If this suit case repeater will not be placed at an elevated location, in relation to your current HT user areas, such as a tower, hill or mountain top, with the loss in cabling & a duplexer - you will be simply wasting funds. Duplexer tuning, is irrelevant, unless all other parameters have been adressed.

Happy Father's Day to those out there who are. Did you get (or get yourself) any gifts related to your radio life?

Just asking. Not sure how the GPS would work or be stored, or not. In a phone it's extensive. Goes back days, weeks, months.. I'll bet it's just on the spot for the radio.

I don't think there is any reason or even memory chips to retain GPS history in them is there? I would think it generates the GPS coordinates as needed when sending them as needed. But maybe some could store a limited history. anyone know?

Due to there being a 5MHz spread between the uplink and downlink, you can make a custom duplexer that would be low loss and provide great separation, but you would have to have a pretty good understanding of electronics and how LC networks work. I am unaware of any commercially available, but if there is one out there and configured to tolerate any reasonable power, it would likely be well over $3,000. I wouldn't be shocked if it was more like $5,000. Actually, the repeaters available from companies like Midland are as expensive as they are, and have such low power, due to having a broad frequency duplexer that covers all channels. They tried to make them as efficient as possible without pricing themselves out of the market.

Wonder if it's hardwired in there that law enforcement could force the info out of it with a special code.