SMC business radios from the 80's & 90's. Any use for amateur radio conversion?
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- Опубликовано: 12 сен 2024
- SMC (South Midlands Communications) not only had those two CB radios, the Oscar 1 (excellent cybernet 134) & the CBM272 (not that good), but were business 2-way radio specialists for decades & also did amateur radio equipment from Yaesu.
One of the viewers has kindly sent me two old business radios. The earlier blue one from the early 80's & the later black one from the early 90's. Here's the words of warning...these radios can't be repurposed onto amateur radio frequencies & can really only be used as a quarry for parts.
Now, in previous videos I've shown Tait T500 & 2000 series radios & Maxon PM100, PM150, SL500, SL70 & even old Apex 520 models being repurposed onto the amateur radio bands. Not all; indeed not many old business radios will move from 160+ Mhz VHF high band to 2M amateur radio band on 145-146 Mhz even if you had the right crystals or programming equipment.
Hoping this information helps someone out there.
Richard G0OJF
Lincolnshire, UK
(C) Tango Systems Group
rshireby@yahoo.co.uk
If you can find the 2 books written by Chris Lorek they are full of info on converting the older pmr radios to the amateur bands. My first radio was a pye pf1 uhf ex-police reciever converted to the local amateur repeater. Had lots of fun playing with the old pye Cambridge and pye Westminster radio's!!.
Surplus Two Way Radio Handbook 1988 and
PMR Conversion Handbook 1997 by Chris Lorek
Ive both, i'll have a look if the SMC1015 which is a yaesu is in them?
the first is most likely
I had a converted Burndept radio, the blue one with those funny Home Office 9v rechargable batteries that have 3 pins on them so you can't put them the wrong way. Range was awful due to the tiny coil antenna in a black resin tube of about 3cm long. The radio had a yellow button on the top for PTT. I'm sure they had about 6 channels, but will have to get them out of the junk box.
Interesting look at the business radios I have used Motorola 2 channel split from base to Mobile and the old traditional Tait radios in past jobs.
The TAIT ones I programmed and used had a diode matrix to select the frequencies. This was around the time I was testing the Dolphin TETRA coverage from a handheld in the car.
Chris Lorek wrote an article for Practical Wireless on converting these to the amateur bands. Would bave been ok to use on your local repeater but the sets are limited by being singke channel.
I've got three.all UHF.
two are on GB3DY repeater with CTCSS no longer any use,
and the cost of crystals not worth changing frequency.
another is spare..
i have at least one Lorek book.
and about ten T500 for 4m, 2m and 70cms..
Back in the early 90s synth ex-PMR gear was very hard to get hold off at reasonable prices. Crystal bound sets like Pye Westminsters & Europas were sold in huge numbers at rallies, they were easy to convert (I learned a lot from Mr Lorek's wonderful book). But even back then the cost of having 2 custom crystals per channel was such that you rarely had more than 3 channels per set including the calling channel. To get around this a few of us used to buy the newly obsolete System 4 VHF car phones these were thought to be useless so often sold for less than a pound but were synth and designed to operate around 159 MHz (from memory). It was a lot of work involving assembly language, reverse engineering the circuit , reading the EPROM then working out how to program it for 2 metres and retune the filters/PA etc.
It was great fun and I learned a hell of a lot about software and hardware. I ended up with about 3 of these sets but threw the last of them out about 15 years ago in house move which is something I now regret.
All Good stuff. I've no Kenwood/Yaesu/Icom amateur radio gear. All my stuff is either ex business radios or built from scratch.
Richard, G0OJF, UK
2nd one is a Yaesu Vertex FTL-2011 4 or 12 channel programable
Model A 134 - 160 MHz
Model C 148 - 174 MHz
I found out that we lost the best crystal manufacture in the States, ICM, several years ago. They were even of capable of recrystaling channel elements used in early Motorola and GE radios. Today I heard that a east coast company restarted crystal production but I do not know if the have the capabilities ICM had to determine the type of crystal, capacitance and resistance just by sending in a working crystal and informing them what frequency that you need. Too bad I never invested in the GE MASTR II low split UHF transceiver which would have been quite easy to move up to the continental EU 70cm bands.
The second radio looks a lot like a Maxon mobile from the '90’s.
Trying to find programming software for some of the older radios is hit or miss. Some programs for early radio may only work with DOS computers and sometimes even slower 8088 and 286 machines. Next item needed is the programming cable and interface if needed. Motorola in the states was notorious for having pickey software. It was dedicated to a particular processor and speed and when windows came into play, which version windows was needed!
We used to use high band business radios, including Motorola at the beginning days of 2 m FM back in the late 60s and early 70s. The FCC went from YBN to what they called narrow band then. Now what is called why band is the former narrow band and the narrow band is 12 kHz channels. Every time the narrow with the radios become obsolete. That will work fine on 2 m if you want a single channel. Back when Marine radios had crystals, we used to convert them to 2 m and order crystals for each channel but you’re right at that time we paid about five dollars a crystal one for transmit and one for receive.
Spellcheck correction went from wideband to narrowband…
I used to work for SMC back in the day. The crystal controlled L1 chassis was used in Yaesu’s repeater of the time as well.
There also used to be a 7 channel UHF version of the mobile which had crystal heater clips on all 7 TX and 7 RX crystals. The thing used to pull about 20amps for the first 30 seconds until it warmed up!
The L4 also came with a 7-seg display with (I think) 24 channels.
I was responsible for testing that model prior to its submission for UK MPT type approval as well as a few mods for incorporation in the production run so it would meet spec.
As far as I recall the main ones were addition of ferrite beads on the connector between the RF and control board to reduce case radiation and some changes to the grounding on the TX LPF to reduce conducted spurious. That, as I recall, was a bit of a compromise. Not enough grounding and the conducted spurious was too high, too much and the spurious was dumped into the chassis and the case radiation went out of spec.
The 4-channel crystal controlled Maxon Apex CGX4020NL had crystal heater clips & is capable of 45W for the USA market. I've got one on 70cms that I bought new at the time. Approved to MPT1326 spec too!
Richard, G0OJF, UK
I still have a very old PYE Base Station that was coverted to 2m, some simplex like S20 and repeater channels for GB3MP. It puts out 50 Watts RF, has valves in it and I had a bag of spare ones for it somewhere. Absolutely NO use for it as it weighs some 80KG in a blue case. It's been in the garage for 25 years! I offered it to various collectors, none of them would even take it for free. It would be a shame to put it in a skip.
1:35 As I recall, the L1 designation indicates Mid Band, 136 - 150 MHz
However, we know this is on VHF high band here in the UKas the crystalled up on 168,xxx RX & 172.xxx TX., the usual 4.8Mhz split
Richard
1015L1 indicates the set is 10 watts, 150Mhz, Land Mobile, 1 channel.
2517L4 indicates the set is 25 watts, 170Mhz, Land Mobile, 4 channel.
@@simondalton3004 Ah yes, it's the L and H suffix on the Mitsubishi RF PA module which is which side of 150 MHz it is IIRC.
I remember those radios
Very interesting thanks.💯👍
There were three in our group some years ago as they were sold by South Midlands Communications) They were brand new and sold very cheap as they were end of line and they were sold to clear the stock room The crystals were from Quartz Slab ,(Worthing I think) A they were expensive they used only one channel as a local net, they were on 70 centimetres ( the good old days)
QuartzLab were in Erith Kent before moving to the Republic of Ireland.
Yes, if it has CTSS they’re supposed to push it before they transmit to make sure someone is not already using the same channel
When radios have CTCSS in the UK, the monitor button must be disabled. On shared frequency systems, when different users have different CTCSS codes, transmit lockout must be enabled when the system is busy with traffic using another CTCSS code.
Richard, G0OJF, UK
You’re bringing back memories. In addition to the monitor button, I remember some of the two-way radios had a grounded microphone clip and when you lifted up the microphone, it would disable the CTSS and you could hear if someone was already Using the channel. Those were the good old days. 73 de WB2UKA
Wow, look at all those pots.
I remember these they had superb receive audio. Im not 100% sure but they may use the same pa module as the ft727 base station. This might be the only place u can find that module for the 726 now.
Yaesu's of that era used a ratio detector consisting of a pair of germanium diodes across a 455khz ceramic resonator, solving both a higher Q than a LC tune circuit
and eliminating trimming. with fantastic recovered audio
The newer radio looks like the Yaesu / Vertex FTL-2011
Thank you. That info has enabled me to look it up & it's 148-174Mhz
Richard
@@ukfmcbradioservicingTango21 Glad to be of help Richard.
I have a few examples of both of these series of radios due to me being an inveterate hoarder.
I've even got a couple of FTLs which are in the 800-900 MHz region. I can not fathom how they arrived on these shores. I bought them on eBay.
Looks like old Zodiac gear.
Good health.
Definitely Yaesu though.
Richard, G0OJF, UK
@@ukfmcbradioservicingTango21 Yep, probably related to the FT224?
more info about that company in Belgium ?
here you are then:-
www.klove.nl/quartslab/
Richard
Could you use something like an AD9850 to replace the crystal?
I've no idea, I'm not an experimenter. Bear in mind the receive and transmit are separate & different crystals, so any synthesised replacement had to be able to generate two frequencies. As the radio is designed for VHF high band, chances are it won't even oscillate on 2M anyway.
Richard, G0OJF, UK
@@ukfmcbradioservicingTango21 this could be done but not sure if it’s worthwhile these days. I modified a few Tait T500’s a few years ago with the plug in diode matrix boards but always avoided anything rockbound. I do like the robust construction of the SMC however.
Im nearly sure the second radio can be programmed using a Motorola rib box and a lead. Rubish tx audio tho. I had one on 70cms once rx was quite good tho.