Minimitter Car Radio Converter - UK Vintage Radio Repair and Restoration Discussion Forum

David Simpson · 27th Sep 2015, 8:58 pm

Folks, I've already scrolled through the threads shown on "Search", but nothing on this wee gem. Those other threads are on M/M's range of larger Tx's & Rx's.
Mobile-wise, this we converter is connected to a car radio set at 1.5MHz, and enables the user to receive 5 amateur bands :- 3.5, 7, 14, 21, & 28 MHz.
Does anyone have a circuit diagram &/or manual please?
It'll work on Mains also.

Regards, David

G6Tanuki · 27th Sep 2015, 9:07 pm

Using a car-radio mobile as the "IF" stage and audio-demodulator was kinda-commonplace back in the 1950s and 1960s when AM was still being used a lot.
[And again in the late-70s/early-80s when US 23-channel AM CB rigs were imported and people wanted to tune in to CB on their car radios]

Does your Minimitter converter have a crystal or is it free-tuned?

What voltages does it need?

What valvs are in there?? From the mid-50s onwards, there were plenty of radios that used "12-volt HT" valves [ECH83/EF97/EF98 etc] which were actually specially-selected versions of the likes of the 'mains HT' ECH81 etc that were chosen because they were at the upper end of the performance-spec for their class].

g4aaw pete · 27th Sep 2015, 9:34 pm

Apologies, but I don't know where this info came from:-

Regards
Pete

HamishBoxer · 27th Sep 2015, 9:54 pm

RSGB I think.I seem to remember adverts for these in the 60,s.

David Simpson · 27th Sep 2015, 10:24 pm

Only just been given this wee set. Great weather this weekend, so outside jobs take priority. But it wont last, so thought I'd get some gen in preparation for a rainy day in the workshop.
I'll open it up & delve inside as soon as I can.
Many thanks for replies so far. Just wondering - did any particular car manufacturer advertise these sets as an optional radio feature?

Regards, David

dave walsh · 27th Sep 2015, 10:38 pm

There are other threads David. Add Alf [Forum member] to Minimitter search via here or external google page. Alf passed on his set to me as mentioned in the Minimitter History thread of 7/10/13. It is a bit of a struggle to extract info

Dave W

David Simpson · 27th Sep 2015, 11:25 pm

Dave, Alf's thread mentioned an MR37 with an 8 way wave change switch. But this set has no model no. & only a 5 way w/c switch. I was assuming his was a much bigger set.
The Minimitter Company's range of equipment is completely new to me, I must admit. But I intend to learn.

Regards, David

dave walsh · 28th Sep 2015, 12:47 pm

Hi David. Yes it was all a bit confusing at the time and remains so. I had presumed that the set I collected from him [eventually] was the same one he mentioned but I hadn't picked up the discrepancy re 8 or 5 wavebands.

The RSGB page that Pete put up here [he may have got it from that Minimitter History thread] seems to definetly ID your set [and mine] as being an M37 with 5 Bands[listed] but info is scarce and obscure. The reviewer clearly thinks it's an M37!

I'll check it all out again when I get back to my example in the North, in the near future. I see that Alf was on the Forum in August so, as you are opening up your Minimitter, it might be an idea to send a pm and see if you can clear up the mystery.

You might want to treat your practical investigation as vital research

Dave W

David Simpson · 28th Sep 2015, 4:45 pm

Right enough, Dave - it would seem,(according to the pdf kindly supplied by Pete), that this set is the top LH half of what W H Allen describes as a MR37 Communications Receiver in his article in the RSGB Bulletin of Feb.1958.
In 1958, as a 13 year old, my head was completely empty of any knowledge of radio technology at the time. I did acquire an ancient Bakelite radio the following year, and I always remember the o/p valve being a PM24B which glowed like a light bulb. Perhaps that initial inquisitiveness heralded my entry into the RAF in 1961 as a Boy Entrant trainee Air Wireless Mechanic.
Now my inquisitiveness is telling me that maybe I should seek out the other two sub assemblies which make up the complete MR37. Rather than consider it as an addition to a car radio(that's what I was told it was), although it looks as though that is what someone has used it as at some stage.

Regards, David

PS. I hope this isn't going to turn out as a time-consuming quest for info on a long defunct company - like BEME, Rees-Mace, Coastal Radio, etc.

dave walsh · 28th Sep 2015, 10:05 pm

Probaly but that's what we are here for

. I'm not even that technical

Dave

David Simpson · 2nd Oct 2015, 10:57 pm

Just had a shufti inside - two valves :- 6BY7 & a 6AJ8.
Just wondering, are there any older amateur guys out there who, back in the 50's & 60's, worked a complete "Minimitter" rig ? What sort of range & reception did it have ?

Regards, David

G3VKM_Roger · 3rd Oct 2015, 7:39 pm

David,

Bob/G6AVI was running his usual Minimitter TX on the VMARS 3615 kHz AM net this morning, maybe he can help?

73

Roger

27th Sep 2015, 8:58 pm	#1
David Simpson Nonode Join Date: Mar 2008 Location: Aberdeen, UK. Posts: 2,851	Minimitter Car Radio Converter Folks, I've already scrolled through the threads shown on "Search", but nothing on this wee gem. Those other threads are on M/M's range of larger Tx's & Rx's. Mobile-wise, this we converter is connected to a car radio set at 1.5MHz, and enables the user to receive 5 amateur bands :- 3.5, 7, 14, 21, & 28 MHz. Does anyone have a circuit diagram &/or manual please? It'll work on Mains also. Regards, David Attached Thumbnails

27th Sep 2015, 9:07 pm	#2
G6Tanuki Dekatron Join Date: Apr 2012 Location: Wiltshire, UK. Posts: 13,995	Re: Minimitter Car Radio Converter Using a car-radio mobile as the "IF" stage and audio-demodulator was kinda-commonplace back in the 1950s and 1960s when AM was still being used a lot. [And again in the late-70s/early-80s when US 23-channel AM CB rigs were imported and people wanted to tune in to CB on their car radios] Does your Minimitter converter have a crystal or is it free-tuned? What voltages does it need? What valvs are in there?? From the mid-50s onwards, there were plenty of radios that used "12-volt HT" valves [ECH83/EF97/EF98 etc] which were actually specially-selected versions of the likes of the 'mains HT' ECH81 etc that were chosen because they were at the upper end of the performance-spec for their class]. Last edited by G6Tanuki; 27th Sep 2015 at 9:13 pm.

27th Sep 2015, 9:54 pm	#4
HamishBoxer Dekatron Join Date: Aug 2007 Location: W.Butterwick, near Doncaster UK. Posts: 8,930	Re: Minimitter Car Radio Converter RSGB I think.I seem to remember adverts for these in the 60,s. __________________ G8JET BVWS Archivist and Member V.M.A.R.S

27th Sep 2015, 10:24 pm	#5
David Simpson Nonode Join Date: Mar 2008 Location: Aberdeen, UK. Posts: 2,851	Re: Minimitter Car Radio Converter Only just been given this wee set. Great weather this weekend, so outside jobs take priority. But it wont last, so thought I'd get some gen in preparation for a rainy day in the workshop. I'll open it up & delve inside as soon as I can. Many thanks for replies so far. Just wondering - did any particular car manufacturer advertise these sets as an optional radio feature? Regards, David

27th Sep 2015, 10:38 pm	#6
dave walsh Dekatron Join Date: Jan 2006 Location: Ramsbottom (Nr Bury) Lancs or Bexhill (Nr Hastings) Sussex. Posts: 5,817	Re: Minimitter Car Radio Converter There are other threads David. Add Alf [Forum member] to Minimitter search via here or external google page. Alf passed on his set to me as mentioned in the Minimitter History thread of 7/10/13. It is a bit of a struggle to extract info Dave W

27th Sep 2015, 11:25 pm	#7
David Simpson Nonode Join Date: Mar 2008 Location: Aberdeen, UK. Posts: 2,851	Re: Minimitter Car Radio Converter Dave, Alf's thread mentioned an MR37 with an 8 way wave change switch. But this set has no model no. & only a 5 way w/c switch. I was assuming his was a much bigger set. The Minimitter Company's range of equipment is completely new to me, I must admit. But I intend to learn. Regards, David

28th Sep 2015, 12:47 pm	#8
dave walsh Dekatron Join Date: Jan 2006 Location: Ramsbottom (Nr Bury) Lancs or Bexhill (Nr Hastings) Sussex. Posts: 5,817	Re: Minimitter Car Radio Converter Hi David. Yes it was all a bit confusing at the time and remains so. I had presumed that the set I collected from him [eventually] was the same one he mentioned but I hadn't picked up the discrepancy re 8 or 5 wavebands. The RSGB page that Pete put up here [he may have got it from that Minimitter History thread] seems to definetly ID your set [and mine] as being an M37 with 5 Bands[listed] but info is scarce and obscure. The reviewer clearly thinks it's an M37! I'll check it all out again when I get back to my example in the North, in the near future. I see that Alf was on the Forum in August so, as you are opening up your Minimitter, it might be an idea to send a pm and see if you can clear up the mystery. You might want to treat your practical investigation as vital research Dave W

28th Sep 2015, 4:45 pm	#9
David Simpson Nonode Join Date: Mar 2008 Location: Aberdeen, UK. Posts: 2,851	Re: Minimitter Car Radio Converter Right enough, Dave - it would seem,(according to the pdf kindly supplied by Pete), that this set is the top LH half of what W H Allen describes as a MR37 Communications Receiver in his article in the RSGB Bulletin of Feb.1958. In 1958, as a 13 year old, my head was completely empty of any knowledge of radio technology at the time. I did acquire an ancient Bakelite radio the following year, and I always remember the o/p valve being a PM24B which glowed like a light bulb. Perhaps that initial inquisitiveness heralded my entry into the RAF in 1961 as a Boy Entrant trainee Air Wireless Mechanic. Now my inquisitiveness is telling me that maybe I should seek out the other two sub assemblies which make up the complete MR37. Rather than consider it as an addition to a car radio(that's what I was told it was), although it looks as though that is what someone has used it as at some stage. Regards, David PS. I hope this isn't going to turn out as a time-consuming quest for info on a long defunct company - like BEME, Rees-Mace, Coastal Radio, etc.

28th Sep 2015, 10:05 pm	#10
dave walsh Dekatron Join Date: Jan 2006 Location: Ramsbottom (Nr Bury) Lancs or Bexhill (Nr Hastings) Sussex. Posts: 5,817	Re: Minimitter Car Radio Converter Probaly but that's what we are here for. I'm not even that technical Dave

2nd Oct 2015, 10:57 pm	#11
David Simpson Nonode Join Date: Mar 2008 Location: Aberdeen, UK. Posts: 2,851	Re: Minimitter Car Radio Converter Just had a shufti inside - two valves :- 6BY7 & a 6AJ8. Just wondering, are there any older amateur guys out there who, back in the 50's & 60's, worked a complete "Minimitter" rig ? What sort of range & reception did it have ? Regards, David

3rd Oct 2015, 7:39 pm	#12
G3VKM_Roger Heptode Join Date: Jun 2012 Location: Southeast Norfolk, UK. Posts: 773	Re: Minimitter Car Radio Converter David, Bob/G6AVI was running his usual Minimitter TX on the VMARS 3615 kHz AM net this morning, maybe he can help? 73 Roger