Modified home base rigs ?

Licence free two-way radio services that now includes both FM and digital channels. Discuss models, modifications and other similar worldwide standards such as FRS and GMRS.
Post Reply
User avatar
Guzzy
Veteran
Veteran
Posts: 4969
Joined: 24 Feb 2005, 02:33
Call Sign: 26TM002
Location: Kent
Contact:

RE: Modified home base rigs ?

Post by Guzzy » 14 Apr 2007, 20:01

"In theory"

Any UHF amateur radio with 6.25KHz tuning steps will be able to be modified for illegal PMR446 use.

In fact, any amateur radio intended for the American UHF amateur radio market will be able to TX on 446 without modification as it's part of their UHF bands!

Also, pretty much any commercial UHF PMR mobile that has 6.25KHz tuning steps will be able to be programmed for PMR446 frequencies as well.

The important thing is that it has 6.25KHz tuning steps and narrow deviation (2.5KHz).

The vast majority of UHF amateur radio kit can only tune in 12.5KHz (or even just 25KHz) steps and that just isn't fine enough. They also tend to have too wide a deviation (5KHz instead of 2.5KHz) which causes adjacent channel splatter (you can be heard on channels either side of the one you are transmitting on).

As a theoretical example: T1 Review Link
If you see a spam (or abusive) post, don't 'reply' to it, don't 'quote' it, don't start a new thread discussing it.
Report it using the Image ('Report this post') button, inside the actual spam post.

User avatar
5thElement
Veteran
Veteran
Posts: 3442
Joined: 15 Oct 2006, 00:05
Location: Liverpool

RE: Modified home base rigs ?

Post by 5thElement » 14 Apr 2007, 21:57

I've seen "Maxon" radios on ebay that have been modified to do this. Like Guzzy said, nearly all UHF sets will be re-programmable someway or another. Im sure it's usually done by reprogramming the eeprom? via computer.

I'd imagine alot dont have ctcss though.
2E0XGA

User avatar
Guzzy
Veteran
Veteran
Posts: 4969
Joined: 24 Feb 2005, 02:33
Call Sign: 26TM002
Location: Kent
Contact:

RE: Modified home base rigs ?

Post by Guzzy » 15 Apr 2007, 00:13

Virtually all commercial PMR sets have CTCSS or DCS.

Unfortunately, they are usually set up so that a single CTCSS code is programmed into each memory channel. So you could program the channels without any CTCSS/DCS or with a specific one, but you can't chop and change once the radio is programmed and you have NO option of changing it without access to the programming software/cable setup.
If you see a spam (or abusive) post, don't 'reply' to it, don't 'quote' it, don't start a new thread discussing it.
Report it using the Image ('Report this post') button, inside the actual spam post.

User avatar
fez
Veteran
Veteran
Posts: 3408
Joined: 26 Jan 2007, 19:51
Location: On the computer

RE: Modified home base rigs ?

Post by fez » 15 Apr 2007, 11:02

Those fedaxin uhf handhelds work on pmr446 and they are cheap, you also dont need a pc to program them you can select tones using the keypad.

Windy_Miller
Top Poster
Top Poster
Posts: 1290
Joined: 08 Jan 2007, 23:46
Location: Scotland, far North

Post by Windy_Miller » 18 Apr 2007, 20:08

In theory, if you wanted to do this, (not that I can imagine why you would, as it its of course illegal...) I believe that after some judicious use of a soldering iron to shift some internal PCB jumpers, the Kenwood TM-G-707 will operate on 6.25 kHz steps in the UHF band, has deviation that can be reined in using the service menu, and the low power setting can be wound down to 0.5 watts, also in the service menu. I believe from reading some specs on the Internet, that it is also equipped with CTCSS and an SO-239 socket which would enable an external antenna to be connected.

Of course, one of the reasons it is illegal is that doing this without a clue about power levels and deviation would result in 35 watts being splattered over the PMR446 band, with far too much deviation, and probably wiping out the channels above and below the one in use. Even with the deviation narrowed down and the power reduced to 0.5 watts, this practice would not be permitted as the radio is not type approved for use on PMR446 and does not incorporate an integral antenna.

So I guess we'll have to stick to using the legal, handheld, battery powered things that fell out of a Christmas cracker! Its intersting to discuss what might be possible in theory though.

Post Reply

Who is online

Users browsing this forum: No registered users and 2 guests