PMR446 Home Brew Base Station

[StormShadow]

Hi there.

I was wondering if anybody would like to share their ideas on homemade PMR446 Base Station rigs made from other UHF commercial radios like old mini cab radios etc etc.

I have a few ideas for some PMR446 projects.

Old ATX computer power supply
Some plywood
An old UHF PMR "preferably a computer programmable radio"
Some old CB radio parts, like signal meter and knobs or channel selector or even the housing of a dead home base CB radio.

Those few items could make a really good looking homebrew PMR446 Base Station

Another idea would be to mount the guts of a UHF radio into an old CB Base housing?

I wouldn't mind seeing some pictures of projects and ideas for PMR446 Base Stations witch can be shared with others that are interested in building a home brew PMR446 Home Base radio.

[Excalibur]

That sounds like a great idea. I would like to see the results of this!

[Farty]

I just use a Motorola PMR powered off my ham PSU. Desk Mic and 2/70 colinear.

[jim175]

Hi there, I saw this one on ebay and have started to build my own with a few differences and mounted in a die-cast box.

http://www.ebay.co.uk/itm/291186685532? ... EBIDX%3AIT

Jim

[StormShadow]

I like that idea but it looks a bit poor if I'm honest. I can see some work has been put into it though and also its made from a cheep baofeng 888 witch aren't all that great for connecting external antennas. I'd like to see your homebrew PMR446 once your done building it.

[TRON]

O RLY??

I've been considering this for quite some time... I did post something in here I think, asking what people would like to see from a base station. I thought it would be nice to have more power than 500mW but then decided against it due to the antenna socket allowing for something with less loss (more gain) etc.

I guess the main thing for me is internet linking which requires extended transmit time WITHOUT melting. Would be nice to remove PA stage and mount it on a **** scary heatsink and also add a low noise (audio and RF) power supply. The power supply could also float charge a little lead acid battery.

Other stuff:
Add USB hub with 4 ports
Add internal com port interface with transformers for audio isolation.
VOX keying with adjustable sensitivity and delay.
Internal memory stick to store radio related programs, bookmarks etc

N-type RF socket.
Built in speaker with the balls to provide decent audio into a room (may require an amp building in)
Built in MIC and PTT switch so that the unit can be used standalone but also a socket for external microphone. DIN socket? 4 pin CB style socket? 3.5mm jack?

The list goes on... Can anyone add any suggestions?

[Admiral]

A lot of ex-PMR kit is 25khz, maybe 12.5 at best, you'd have to do some serious offsetting to make it work.

BTW, that Baofeng 'homebase' looks shíte.

[TRON]

I was just going to tear apart an old 446 handheld. Maybe a Motorola handie pro or similar.

[Admiral]

Going back to the last Century, old crystal channeled sets would work very well if you could afford 16 tailor made xtals, and they used to pump out some serious RF, and sounded lush. No CTCSS though

Maybe the clever eprom boys could do the trick?

[TRON]

If I was going to go to that kind of effort, I'd build something more capable than a 446 rig... I keep seeing various kit radios for sale on Ebay etc, and some of them really appeal to me. Simple to build, can be as rugged as you make it but none of the bells and whistles of multi-thousand pound "big four" rigs.

For now, on the subject at hand, I'd like to make something 446. In a 19 inch rack case. Maybe even make it blend.

[jim175]

Hi there, Here is my first attempt, its a bit crude but i'm happy enough, I will make another with a UVB5 instead and without the banana sockets, The box was re used from an old project and had some holes already drilled. As you can see I wired the mic up with a 6 pin cb mic for more strength, that was a major weak point on the e-bay link that I posted. Any thoughts, ideas for the next one?

Jim

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[jim175]

And a few more:

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cheers, Jim

[Excalibur]

Very nice work jim175! I like the idea to use a cb style connector instead. Does it help with the radios performance?

[jim175]

Hi Excalibur, The 6 pin connector is just a way to make a better conection between the mic and radio without any strain on the radio's pcb. I have wired 3.5mm and 2.5mm plugs from the radio to the back of the 6 pin chasis socket and then re-wired the mic cable from a two pin kenwood plug to the 6 pin cb plug. Its much more heavy duty.

Jim

[Farty]

Why not just use a commercial PMR?