Ex-Commercial Radios On 6m ?

[VK4EB]

Hi All

Very old thread...but..

I have a couple of Tait T2020 MkII 66-88Mhz, and would like to convert them to 50Mhz. I've already done a Simoco Prm80 to 6 metres but would really like to use the Taits as they are remote heads.

Has anyone got the detail to do the mods?

Many thanks

Alan
VK2TVQ

[VK4WDM]

Things were much easier in the "old days." I had a WW2 tank to tank set that was just a basic modulated oscillator on about 70MHZ (give or take a meg or two) and you got it on to 6m by re-shaping the output coil with a pair of pliers. Once I got two enthusiastic with the pliers and ended up on a truckie frequency which meant a visit from the RI He was very nice really - gave me the bollocking I deserved then went and got his frequency meter and helped me get the thing on the right frequency (give or take a few KC)

73

Wayne VK4WDM

[VK4EB]

I do remember building an ATV transmitter from an old valve PYE Vanguard? back in the UK, and had it running for hours. Until someone called me on 2m to see if I could hear who had been keeping the the local 70cm repeater open all day with a buzzing noise.

It was at this point I remembered that the crystal I was using was actually for that UHF repeater, not for ATV... still, all in the spirit of learning about RF.

Anyhoo, anyone got any ideas on the Tait T2020, to 6 metres, I did see someone earlier in the thread who had some info, if they still have it.

Cheers

Alan
VK2TVQ/G8UFN

[VK3ZAZ]

Filters in Tait VHF Lo band designed to cut off above CH2 (old analog)
So you will have to redo them.
or check if tait had a lo lo band in Australia 35-56 MHZ

I prefer Motorolla which I used for beacon easy to tune.

I am also unsure if the tait will program to the Australian repeaters.

However nothing is without a try.

Threw all the old radios out here no value so if you get it going that's good

I scanned all FM repeaters here last summer and barely heard a signal

We have big repeater on Mt William 5000 feet amsl and no one uses it.

People hardly use 2M fm repeaters and 432 MHZ lost caiuse.

cheers

[VK4EB]

Yep, I have a couple of Motorola GM950 66-88, haven't managed to get the software to accept below 56Mhz, I opened up the software for 50 to 88 in a hex editor. Unfortunately when I try to enter anything below 56Mhz , the software seems to do a calculation, and shows 100+ Mhz, odd.

The Tait front ends aren't a problem if I can simply get the Tait software to accept below 56Mhz, thought someone may have played in the past. No Tait T2000 below 66-88, never produced that I'm aware of, even in the US.

I'm guessing there must be a software hack for the Tait to allow below 56Mhz, if anyone has it.

Cheers

Alan

[VK7DB]

Watch this space!.........................

[VK4TIM]

I have successfully modified several Philips/Simoco PRM8025s from 66-88 down to 50-54, and they work REALLY well on 6m FM, and I mean REALLY well.
The original designers would probably love to see just how well they work.
A full rework of the TX PA is required, extra capacitance on both VCOs to make them resonate lower, and a full realignment, and for about 3 hours work, you get a great, simple 6m FM radio.

If anyone wants a whole lot of PRM8030s (remote head model), PM me and I'll attempt to help you. I know where there's lots of them that will mod down to 6m.
VK3SMB has done a write up on these and produced an article that was published in AR (a couple of years ago), his modified firmware makes the modification and programming much tidier and simpler, and I would recommend this approach when modding PRM80s for 6m.

As for the Tait T2010/2020 radios, they should go down without a major problem, I'm fairly sure that Rob VK4AB has done it, I know he has a few VHF radios that he has/will bring down.

I know we've retuned T800 series 1 and series 2 base station equipment to 6m FM, they make great repeaters, I have a series 2 waiting for retuning down to 6.
The Auckland (53.725) and Christchurch (53.850) New Zealand repeaters are both T800 series 2, their receivers are VERY sensitive too.

[VK4EB]

Yes, I've done the PRM 80 mod, and it's brilliant, thanks to VK3SMB, haven't changed the firmware yet, I'll purchase his firmware at some point, I just don't have an eprom eraser.

I have boxes of t2000 66-88 at work, so if I can get the software to program, I'll convert a few and donate them to our local club, but it's the software that's got me stumped. I can't seem to see where in the software the band limits are, at least not in the windows 3.00 version.

If Rob VK4AB has done it, I'd love to know how, it'll be something simple, it always is!

Thanks all for the input so far, I've posted the question on the Tait Yahoo group as well, but nothing back as yet.

Cheers

Alan
VK2TVQ/G8UFN

[VK3VS]

Dion Alerted me to this post.....

I have a documented T2020 Mod with job file here:
http://www.vk3smb.com/wiki/index.php/6_ ... %282020%29

Its a similar amout of work to the PRM80 to do it properly and minimise parasitics

Matt VK3VS/VK3SMB

[VK4EB]

Hi Matt

Absolutely brilliant, I've imported the 6 Metre data file into the Tait windows TPU 3.010 and it all seems fine, will have try out when I get home. If you don't mind I'll post your URL to another board as there are a few people looking for this information.

I'll get a couple of radios for our local club as I'm sure there will be a few will want to try this.

Thank you for taking the time to put the info all into a WIKI, I just couldn't find it.

Cheers

Alan
VK2TVQ/G8UFN

[VK3VS]

If you don't mind I'll post your URL to another board as there are a few people looking for this information.

Thats fine, I dont mind links to my page, just dont copy and paste it somewhere else. Where else do you plan on putting it?

Thank you for taking the time to put the info all into a WIKI, I just couldn't find it.

It only went into the Wiki because VK7DB and I were discussing other stuff and it came up. My whole site will eventually be in that wiki. I'm sure google doesnt know about it yet. Well I havn't told google

Ta, Matt
VK3VS/VK3SMB

[VK4EB]

Hi Matt

I wouldn't mind posting the URL to the Tait Yahoo Group with all credit to yourself, there was a fair bit of interest when I asked a similar question on there.

Plus one last question, do you have the original Tait software that you used to put the 50Mhz frequencies in, every Tait software I've tried won't accept out of range frequencies. Only asking as I might add a few frequencies that I might like to play on.

I've programmed one of the T2020's to 6M already and it's running 15Watts and receiving pretty deaf without any changes, so that's a job for later tonight

Thanks again

Alan\VK2TVQ

[VK3VS]

Plus one last question, do you have the original Tait software that you used to put the 50Mhz frequencies in, every Tait software I've tried won't accept out of range frequencies. Only asking as I might add a few frequencies that I might like to play on

What software????? Your hanging onto a good old bit of code bashing right there. Why do you think I said you cannot verify the settings when writing it to the radio?

Dont slack off re-winding the coils, you'll put a harmonic into the FM broadcast band.............

And, lastly, not all the credit goes to myself. That mod was handed to me from someone (I Cant remember who, sorry), about 7 or 8 years ago.... When I was looking to put the T700 into 6M.

FYI, VK3ELV has a pretty good mod for the T500 into 6M, it does 40W out at full steam!. I am trying to get him to document what he has done. Another reason for the Wiki.. Get those who are left still modfiying things to document it in a place we can all use it.

If I have to modify a piece of software to allow 6m freqs into it, I'm going to want $ for my time. it is not an easy job, hence why I ask for a nominal fee for my prm80 firmware. eventually I'll break even with it.

Matt

[VK4EB]

Hi Matt

I thought you may have programmed it directly in hex, I looked at the Tait programming code, managed to change the 66-88 on the Tait DOS software to 50-88, but the software still won't accept 50mhz directly. Your a better coder than me, by a long way, I can see the frequency in the saved code plug, but I can't for the life of me work out how the hex works out to a frequency, tried long/short Intel/Mot but I can't make any sense?

The PRM80 does need your firmware, a few sproggies with just the changed xtal. Damn good work on that, you must have spent a lot of time working it all out.

I've completed the receive end of the Tait, all good, need to take it into our workshop tomorrow to check the actual sensitivity on a test set, but appears good for now. Tomorrow night I'll do the TX coils, and bung it on the spectrum analyser at work to check the output purity.

I'd still love to know what the relationship is with the Tait "code plug" to coin a phrase, and the frequency, I'm obviously overlooking something while looking at the hex, but I don't know what.

Edit: I've just grabbed the firmware for the PRM80 off your site, maybe you'll eventually break even

Thanks again

Alan

VK2TVQ/G8UFN

[VK3VS]

I can see the frequency in the saved code plug, but I can't for the life of me work out how the hex works out to a frequency, tried long/short Intel/Mot but I can't make any sense?

Usually, I edit something, compare, edit again, log my findings in a spreadsheet and work out the algorithm. I have done this with Instrument clusters, radio code dumps, and recently been playing with the ford incode/outcode system to work out how to do that when a dealer is 50km or more away and I have a dead one.......

The PRM80 does need your firmware, a few sproggies with just the changed xtal. Damn good work on that, you must have spent a lot of time working it all out.

Lets see, the hardware only took around 8 or 9 hours between Phil and myself. Phil has full credit for the PA re-design, I was the one game enough to try and add Inductance to the stripline to stop it running away. (I had more boards than him). The firmware and FPP, yeah I rekon around 100 hours went into that. All me, as someone, somewhere said it couldn't be done.

I believe that the guts of that mod came from Tait. When I did one years ago, I didn't have access to all the gear I have now, but I couldn't fault it. I rekon its sitting in a box somewhere. I should find it and have a look.

I'll dig that firmware up and email it over the weekend for you.

[VK2GFR]

A bit pricey, but do-able is the Kenwood TK6110-2. Only FM & 32ch but a 70w PA. I've been trolling the e-boy site for deals.
Some can do both 10m repeater freqs & 6m channels.
Software is readily available & only needs a hex converter prg to get em up n going (plus a tune).
Only reason I havn't bought one.... not remote head style (for the car).
**I have one of Tim's PRM-8025 & when the band is open, it's a hoot to work long distances on FM, even on a J-Pole vertical.

[VK6ZFG]

The TAIT T2000 series can be converted down to 6M.

I have converted both T2020 and T2010 radios to 6M. T2020 will cover to well below 50 Mhz but the T2010 will only do the top end of the 6M band and not all the FM channels due to limitiations in the T2010 controller board. Have not checked a T2015 as yet.

The controller board places limitations on how low you can program the radio.

The modification involves (besides coils/capacitors) changing the 12.8 MHz reference oscillator to 10.24 MHz. This makes the radio have 4 kHz steps instead of 5 kHz. The radio needs to be programmed as if it was a 66-88 Mhz radio knowing that the actual transmit frequency will be less due to the lower reference frequency. RX frequency is a bit more complicated as one needs to take into account the IF frequency but can also be achieved.

[VK7DB]

While we are on this subject it might be worth mentioning that the Unilab KL70 to 6 metre conversion seems to be gaining some popularity..

We are running one on VK7RMD 53.800, and it goes very well by all reports..

[VK3XYX]

How much effort is required to get the Unilab KL70 onto 6 meters. I was just going to pulll it to bits but if its not to much effort it might be worth while to convert it.

Regards
Garry

[VK2GFR]

A bit pricey, but do-able is the Kenwood TK6110-2. Only FM & 32ch but a 70w PA.
Some can do both 10m repeater freqs & 6m channels.
Software is readily available & only needs a hex converter prg to get em up n going (plus a tune).

From this old post I did buy one from the U.S.
Only reason I haven't got it up on air is that there appears to be a "glitch" in radio to computer handshake.
CPU says "check connection".
I've put the word out to anyone that might be able to help, but so far no responses & lack of time & effort on my behalf to nut this out, otherwise I'd be on 52.525 FM .