Replace mini uhf on mobile radios with pcb bnc

[BIODTL1997]

Has this been down before? I'm specifically wanting to do this to a GM300 and M1225.

I'm trying to turn these mobiles into desktop radios that are easily-interfaced with small antennas that I have in abundance. I'm also looking to replace the 12V power interface with a standard female coaxial 12V DC socket, to use with another very abundant power transformer. (These will only be used for RX so 500ma should suffice)

If anyone has any bright ideas or has done this before, please let me know. Thanks!


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[fdscan]

Adapters!!!

As far as the antenna goes, just google for a mini UHF to BNC adapter. I just did and found this Mini UHF Male to BNC Female Adapter. You might be able to find it cheaper on eBay, Amazon, or another site, it all depends on where you want to buy it from.

Now for the power supply... I see what you're trying to do. Theoretically it would be nice. That's how lots of scanners are... Hence why they are easy to plug into the wall without any crazy power supplies or anything. One way of going about it is connecting a series of adapters together, but I don't think that would work out well. If you snipped the coaxial end off and maybe just connected that to two leads coming off of whatever power interface your radio uses and secure them with some sort of connector. For example, if you have the quick-disconnect type plug where one side is guarded with the plastic and the other is bare and when you plug them in, they both match up, you could buy one from Radioshack or an auto parts store or something and simply connect the positive from the wall transformer to the positive lead coming from the quick-disconnect plug, and the same with the negative. Use whatever connectors you like to use, and if you want to do it right, probably best to heat shrink it or tape it to seal it up.

Personally I've never done this. Theoretically it should work...

If anyone finds anything wrong with that plan don't be afraid to point it out. I'm just kind of rambling on here.

 

[KC4YIN]

Radio Shack has this same adapter. I just bought some for a CDM 1550.

 

[902]

I was in the radio maintenance business at a COSC when those mini-UHF connectors came into use in the Motorola Radius products, and then in the full-line products. My co-workers' and my thoughts were along the lines of "what were you thinking?" but it probably shaved a fraction of a cent off the production cost and made them millions over time, not to mention somewhat of a trademark connector. In the field they just vibrated out, so we would do various Locktite and tiewrap fixes. Or just keep going out to mostly cement mixer fleets.

We've tried over the years to make changes with BNC connectors with some success, but I think the effort will consume more of your time and money than using an interseries adapter.

If you do decide to retrofit the equipment directly, you will have to go through quite a few resources, like Pasternack and Digikey to find a connector that fits the size, then if you send it in for repair, the shop might need to find the proper adapter to interface with it. You might also have to craft up little pigtails into Taiko-Denki TMP or SMB connectors. I am told the mini-UHF does exhibit 50 ohm impedance, so you are not saving anything in terms of insertion attenuation or impedance mismatch.

As for using small antennas (magnet mounts?), the manufacturer might discourage that (another reason for a mini-UHF) due to RF exposure levels. Back in the day, we did do a lot of mag-mounts on top of file cabinets, or inside dropped ceilings. Today that might be questionable if a shop did that, at least near where people within the field of the antenna.

 

[SteveC0625]

Like others here, I'd just do adapters. Mini UHF to BNC are readily available. The mating connector used on the GM300 and M1225 can be readily found on Ebay in quantities of 5 and 10 on a short pigtail. Perfect for making up your own adapter to the standard coaxial 12vdc. They're not rated for much amperage but since you're looking at Rx only, that's not an issue.

The time and effort to open up the radios and install the connectors is more than one might think. And there is the potential to break things in there. Better to make or buy the adapters and move on.

 

[rescue161]

Why not just use a mini UHF connector? They are cheap and easily put on any type of coax that you may have. Adapters are for testing. Crimp on the right connector and be done with it.

 

[BIODTL1997]

Thank guys. Yea, it would be a waste of time, but then again these things are cheap these days and I'm a addict of taking things apart and exploring/modifying. But for this application, pigtail power connector to a standard 12V coaxial transformer and one of these antennas it is!

2 Pack DirecTV Dish Network RF IR UHF Remote Receiver DVR Dual Tuner TV Antennas | eBay

(the quick release RF connector fits great on a female mini-UHF interface!!)

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