AWA / TAD M-8, how to program 144MHz - UK Vintage Radio Repair and Restoration Discussion Forum

darren166957 · 6th Jun 2020, 11:02 am

Hi, I have one of these big old VHF high band PMR sets from the 1980s. I know how to program it, but it only accepts frequencies down to 148MHz. Does anyone know how to extend this so I can get it onto 2metres? I'm assuming I have to edit/replace the eprom.
These sets seem to exist in more than one version, covering 148-174MHz and 144-174MHz, and maybe others.

Darren G1ERM.

Jon_G4MDC · 6th Jun 2020, 11:29 am

Have you been here Darren? I don't know if it's any use but it might be a start.

http://www.va7alg.ca/what.html

The download for the manual seems to work. It is a classic 2 chip synthesiser with Divider/Swallow Counter and Dual Modulus prescaler.

The data is serially loaded so hardware hacks with binary subtraction are out e.g. my method for the HEF4750/1 in the UHF FM914 where 70cm was locked out due to proximity to Aus CB band. (didn't you have special code for this once upon a time, or is my memory playing tricks?) Eventually I hardware hacked it and I did 6m the same way from PMR Low Band. You could give it a 20MHz HW shift which the uP had no idea about.

It's change the band limits programmed in EPROM I think unless you want to intercept serial data with a PIC and perform tricks that way.

6th Jun 2020, 11:02 am	#1
darren166957 Diode Join Date: Nov 2014 Location: Swindon, Wiltshire, UK. Posts: 2	AWA / TAD M-8, how to program 144MHz Hi, I have one of these big old VHF high band PMR sets from the 1980s. I know how to program it, but it only accepts frequencies down to 148MHz. Does anyone know how to extend this so I can get it onto 2metres? I'm assuming I have to edit/replace the eprom. These sets seem to exist in more than one version, covering 148-174MHz and 144-174MHz, and maybe others. Darren G1ERM. __________________ Darren G1ERM.

6th Jun 2020, 11:29 am	#2
Jon_G4MDC Nonode Join Date: Nov 2015 Location: Welwyn Garden City, Hertfordshire, UK. Posts: 2,015	Re: AWA / TAD M-8, how to program 144MHz Have you been here Darren? I don't know if it's any use but it might be a start. http://www.va7alg.ca/what.html The download for the manual seems to work. It is a classic 2 chip synthesiser with Divider/Swallow Counter and Dual Modulus prescaler. The data is serially loaded so hardware hacks with binary subtraction are out e.g. my method for the HEF4750/1 in the UHF FM914 where 70cm was locked out due to proximity to Aus CB band. (didn't you have special code for this once upon a time, or is my memory playing tricks?) Eventually I hardware hacked it and I did 6m the same way from PMR Low Band. You could give it a 20MHz HW shift which the uP had no idea about. It's change the band limits programmed in EPROM I think unless you want to intercept serial data with a PIC and perform tricks that way. Last edited by Jon_G4MDC; 6th Jun 2020 at 11:56 am.