Bush ETR82 - MW/S1/S2 portable, 1 valve/6 transistor hybrid c.1959

[Robert Darwent]

I obtained this radio from a Canadian seller in British Columbia earlier this year. It is one of the rarer of the Bush portable variants that all share the same TR82-type case.

This one, the ETR82, being an export set having medium and two shortwave bands instead of the more commonly found medium and long, and employing an hybrid one valve, six transistor circuit.



On first impressions the set looks like the more common TR82C model, but notice that the red tuning dial is different;



Also notice the three push buttons on top instead of two and the inclusion of an antenna like the TR82CL, TR82DL, VTR103, VTR103C variants;



There seems a total absence of service information for this set. I tried every source I could think of and still turned up a blank. From what little information I could find, the set appears to have only been manufactured for a period of around twelve months or less, that interval being mid 1959 to mid 1960. My set has the date October 1959 on its Plessey made electrolytics.

Tracing the circuit physically myself, the ETR82 appears to be a cut and splice of the front end of the EBM60 model and the rear of the TR82B. It uses the waveband switching and a DK96 valve as a mixer/oscillator from the EBM60, followed by a pair of OC45's as IF amplifiers, an OC71 as an AF amplifier, an OC78D as a driver, and a pair of OC78's in a push-pull ouput arrangement, all taken from the TR82B circuit.

The set is powered from seven D-cells. One cell is in an holder by itself and is the LT supply for the DK96. The other six cells are in series to make up a 9 volt supply for the transistor circuitry, and to feed a vibrator which produces around 65 volts to power the DK96 front end. In the picture below the DK96 valve is shown approximately in the centre of the chassis, and the vibrator can just be seen hiding behind the single D-cell at the bottom left;



The reason for the set's such short manufacturing period was due to the speed of suitable transistors becoming available on the market that could reliably work at the higher shortwave frequencies. Initially Bush designed the EBM60 in 1957 which is an all battery valve export model have MW and two SW's ranges. This was superceded by the ETR82 shown here in 1959/1960, having the same tuning ranges but replacing all but the first valve with transistors. Which was quickly in turn superceded by the ETR92 model which is the all transistor version which first appeared in the second half of 1960.

The set arrived in quite a good condition. It was grubby but nothing too bad. I fitted a set of new batteries and switched on. Nothing but a very faint whine from the vibrator can. I switched off and gave the chassis a close inspection. I couldn't find anything obvious that seemed at fault. The solder connections on the vibrator looked a little dull and dry so I decided to remake them. This cured the problem! The set produced good volume and clear reception on all tuning ranges. It has worked excellently ever since!

I then totally dismantled the set. Cleaning the plastic case, first with foam cleanser and a toothbrush, then after drying off a good polish with Brasso. This removed any fine scratches and restored a nice shine to the plastic. The blue rexine on the sides was also cleaned with the foam and toothbrush, then polished with a wax furniture polish. This brought it up lovely. All the metal trim was polished with a car chrome polish. Everything was re-assembled and the end result is shown below;



These particular portables are what renewed my interest in collecting vintage radio's again. I now have examples of 12 of the 13 variants in my collection, I'm just missing that elusive ETR92 set!

[Steve_P]

That's a rare set! Rarer than the VHF Version! Nice job too.

Cheers,

Steve P

[GJR 11L]

Robert, repeat after me; "I am a jammy devil!"

That's just lovely and only the second of the model that I've ever seen.

I don't want to encourage you, but thirteen variants?
I have a feeling that, allowing for such things as the change from 0c44/45 to AF117 and the differing audio stage of those later sets, then the trim versions on the 103, there may be even more that you have to buy before the collection is truly complete!

I love the idea of running the set from the 'D' cells, and wish that they'd stuck with that idea for the home-market versions.

So, how would it compare with the EBM60 for sensitivity?

Very nice, well done on finding it and on preserving it in so pristine a condition.

[batterymaker1]

That is the strangest hybrid I've ever seen. And a VIBRATOR set, on top of everything....

[Robert Darwent]

Originally Posted by GJR 11L

Robert, repeat after me; "I am a jammy devil!"

Hello John

I've got to admit it! Since the middle of this year I have been a 'jammy devil' as regards acquiring some quite scarce sets. I've been very lucky indeed!

In May I got the Bush EBM60, which is the subject of another thread, in June the Bush ETR82, in August another Bush EBM60 still complete with its original plug-in whip antenna, in September a Berec Commander, and recently a Vidor Vanguard, also subject of another thread. And by the way about a year ago now I did have a chance of a Bush ETR92, also in British Columbia!

When I was talking about 13 variants sharing the same TR82-type case I was going on Bush's type and model numbering on the small plate underneath the sets. From what I believe to be correct the variants are the following in order of release, I'm not including the modern replica versions of course. The dates given are those on my particular examples;

01. 237 - MB60 - LW/MW, Earlier type B147 battery, Coffee case, Red rexine, Brass fittings - Sept 1957
02. 237 - MB60 - LW/MW, Later type B131 battery, Coffee case, Red rexine, Brass fittings - Nov 1958
03. 240 - EBM60 - MW/S1/S2, Export all valve set, Coffee case, Red rexine, Brass fittings - Jul & Nov 1957
04. 345 - TR82B - LW/MW, OC transistors, Coffee case, Brown rexine, Brass fittings - May 1959
05. 346 - TR82C Mk1 - LW/MW, OC transistors, Blue/green case, Blue rexine, Chrome fittings - Sep 1959
06. 355 - ETR82 - MW/S1/S2, Export hybrid, Blue/green case, Blue rexine, Chrome fittings - Oct 1959
07. - ETR92 - MW/S1/S2, Export all transistor, Blue/green case, Blue rexine, Chrome fittings - c.1960
08. 462 - VTR103 - MW/LW/VHF, Cream case, Tan rexine, Chrome fittings - Aug 1961
09. 528 - TR82C Mk2 - LW/MW, AF transistors, Blue/green case, Blue rexine, Chrome fittings - May 1963
10. 530 - TR82D - LW/MW, AF transistors, Cream case, Tan rexine, Chrome fittings - Feb 1963
11. 622 - VTR103C - LW/MW/VHF, Blue/green case, Blue rexine, Chrome fittings - Jan 1964
12. 653 - TR82CL - LW/MW/208 Luxembourg, Blue/green case, Blue rexine, Chrome fittings - May 1964
13. 655 - TR82DL - LW/MW/208 Luxembourg, Cream case, Tan rexine, Chrome fittings - May 1964

I stand to be corrected of course if anyone has more information?

Regarding the ETR82's sensitivity compared to the EBM60, I consider the ETR82 to be a good bit better. Both sets are pleasing to listen to, and share similar peformance on LW/MW. But the ETR82 is noticeably better on the SW's. Of course the EBM60 wins on tonal quality with its rich valve sound.

Many thanks for your nice reply, you're very kind

[batterymaker1]

You need to do a website devoted to these variants. That is some fascinating stuff!

[Robert Darwent]

Originally Posted by batterymaker1

You need to do a website devoted to these variants. That is some fascinating stuff!

Thanks for your replies Bill, appreciated

Yes I have thought before about taking photo's of them all, inside and out, and creating a gallery in a thread on the forum, largely for reference purposes for everybody.

The Bush TR82 type's are quite popluar, in the UK at least, and I would have thought it true that most collectors on this side of the Atlantic have had at least one in their collections at some time or other.

[Paul_RK]

I'd not realised the ETR92 was quite so hard to find: I'm the happy owner of one that turned up at the local flea market some ten years ago. Serial 421/08777, so that completes (as far as we know) your table. Interesting that Bush decided to extend the band coverage a little in the HF direction when capable transistors came along - the 92's dial comfortably includes the 13 metre band.

Paul

[Robert Darwent]

Originally Posted by Paul_RK

I'd not realised the ETR92 was quite so hard to find: I'm the happy owner of one that turned up at the local flea market some ten years ago

Paul you lucky man! Don't suppose you'd consider doing a straight swap for one of my EBM60's by any chance?

Thanks for informing me that 421 is the Bush type number for the ETR92. Your set is only the the third I've heard of. I know that Alvin (soundmix100) also owns one, and the only other that I've heard of was the one I lost out on in Canada a year ago.

Yes Bush did alter the SW coverage slightly with the ETR92, the ETR82 and EBM60 are exactly the same in that department. As you say, probably because it was possible with the transistor's that had become available

[GJR 11L]

Originally Posted by rrdmpb

Thanks for your replies Bill, appreciated

Yes I have thought before about taking photo's of them all, inside and out, and creating a gallery in a thread on the forum, largely for reference purposes for everybody.

Ooh yes, a photo gallery would be good.

Originally Posted by rrdmpb

The Bush TR82 type's are quite popular, in the UK at least, and I would have thought it true that most collectors on this side of the Atlantic have had at least one in their collections at some time or other.

Very popular here!
Understandably so though, as a good one is a joy to behold and it's better than spending money on alcohol, football or tobacco!

[batterymaker1]

Even I have a TR82--Cabinet's chassis mounting holes are all busted, and the chassis' propped up by a piece of wood, but from the outside it looks and plays great!

[GJR 11L]

Bill, would it be worth the cost of shipping from here in the UK to get a new cabinet central section for your set?
Sorry, Robert, don't mean to hijack your thread, but many of us this side of the water have spares for these which may have straight or at least repairable chassis mounts, so a request for such a thing in "parts wanted" may bring a result!

[batterymaker1]

I dunno, I'll need to crack open my TR82 again and see what I'd need for spare parts. It's been about eight years since I've futzed with it....

[kalee20]

Well I'm gobsmacked at the little miniature vibrator working from the dry batteries, to supply HT for just 1 valve.

Bush must have really wanted to hang on to the market share, to produce this hybrid for such a short time, instead of taking a year out waiting for better high-frequency transistors so that they could throw out the valve.

Just think - if they'd waited another couple of years, there would have been cheaper higher-power transistors. Then, they could have used a just couple of these to make a power converter from the 'D' cells, thrown away the vibrator and all the transistors, and used all valves in the signal path!

Wishful thinking I know...

[Robert Darwent]

Originally Posted by Steve_P

That's a rare set! Rarer than the VHF Version! Nice job too.

Sorry missed replying to you earlier. Thanks for your kind comment Steve

Originally Posted by kalee20

Bush must have really wanted to hang on to the market share, to produce this hybrid for such a short time, instead of taking a year out waiting for better high-frequency transistors so that they could throw out the valve.

Don't forget we all have the benefit of hindsight and know now how quickly suitable transistors became available. I think back in the late 1950's it wasn't so clear cut, and I imagine most manufacturers were caught out design-wise by the rapid development and availabilty of high frequency transistors.

I would assume that at the time they thought the lead-time was several years rather than the several months it actually turned out to be! Still it did contribute in the production of oddities such as the ETR82 for us all to collect now some 50 years down the line!

[howard]

Hello Robert,

This is only the third ETR82 that I've ever seen and by far the best one too and it's a very interesting variant of the MB60/TR82.

Howard

[Alvin]

Originally Posted by rrdmpb

I obtained this radio from a Canadian seller in British Columbia earlier this year

That's interesting, my EBM60 came from a seller in British Columbia. I found my ETR82 in the UK - not as pristine as yours as it has a chip out of the cabinet on the lower front edge (see pic)

I'm just missing that elusive ETR92 set!

I picked up a nice example of one of those at Harpenden some time back

Alvin

[Robert Darwent]

Originally Posted by howard

This is only the third ETR82 that I've ever seen and by far the best one too...

Thanks Howard for that very kind remark

Originally Posted by soundmix100

That's interesting, my EBM60 came from an seller in British Columbia.

Thanks for your reply Alvin

Yes there does seem to be a lot of the Bush export sets out there! As you say, your EBM60 came from British Columbia, so did my ETR82, and the ETR92 I lost out on was also out there. By contrast both of my EBM60's came from fairly nearby, within 60 miles of my location!

[Robert Darwent]

Regarding some new information that has come to light;

https://www.vintage-radio.net/forum/...ad.php?t=25554

It is has now been confirmed that what was widely taken by many, myself included, to be a 'vibrator' in the ETR82, is actually an 'inverter'. Therefore my initial description in this thread of the circuit should have correctly read as follows;

Originally Posted by rrdmpb

...six cells are in series to make up a 9 volt supply for the transistor circuitry, and to feed an inverter which produces around 65 volts to power the DK96 front end.

Many thanks to Alvin (soundmix100) for passing on this new information from Mike Izycky!

[Studio263]

Here's another early transistor set that uses an inverter for just one function:

www.beocentral.com/products/lit1000

In this case it generates the bias needed for the FM varicap tuner. The layout is similar to the Bush design, the inverter circuit is hidden away in a metal box in the bottom. The earlier 500 model used a seperate 22.5V hearing aid battery for the bias instead, two 12V car alarm fob batteries make a good substitute.