Moreton Cheyney

[allan]

I picked up an odd looking chassis a few days ago and noted the name "Morton Cheyney" on the cardboard dial so looked up this and found not much information, but a little on this Forum.
The receiver outwardly looks scruffy but under the chassis is in good order so may be worth restoring.
There's one valve missing which might have been a frequency changer or an RF amplifier depending on the design which might have been restricted to pentodes. I can probably trace the wiring but it would be simpler if I had a circuit diagram or a brochure carrying the receiver spec.
I'm still working on the page, but it can be seen here.
http://www.radiomuseum.co.uk/Morton.html
I got the set in a job lot containing an unmolested R1132A and a new T1154 plus what seems to be a PSU chassis for the Morton Cheyney, but includes what at first appears to be a 100 watt push-pull KT66 modulator. Presumably the transmitter that went with the receiver was scrapped? The PSU chassis has yet to be identified as it appears to be ex-MoD..
Allan G3PIY

[Nickthedentist]

Interesting!

Note the spelling seems to be Moreton Cheyney... might help with search results I suppose -;

Nick

P.S. Your website looks full of good stuff too, thank you.

[allan]

oops.. didn't notice that Nick. Done but I can't edit the post?
In fact I get more hits with Morton so I'm not the first...
thanks
Allan G3PIY

[paulsherwin]

There are variant spellings in the period magazine articles.

[allan]

I looked up the 1949 address in Stafford and I reckon the company was about to fold. It looks like a flat above a shop close to Stafford Gaol; a long way from their London WC1 address in 1946. Perhaps 52a was where they stored their unsold stock?
Allan G3PIY

[boxdoctor]

Slightly O.T., the address given as BCM/REME in one of those ads. is what was known as a "Monomark" address.
They were used by companies who did not wish their true identity to be revealed to the general public. One would apply to Monomark, and they would (for a fee, of course) supply you with a Monomark code (which you could to some extent choose), and any communication would be passed on to you. They had, I believe an arrangement with the G.P.O. to have all monomarked correspondence passed to their own mailing address, from which it was sent on to the relevant subscriber to the scheme. I believe Monomark closed many years ago. Tony.

[G6Tanuki]

I'm totally perplexed about the two 3-gang tuning-capacitors: they look to be both of the same sort-of value - is this really *five* signal-frequency tuned-circuits and a LO? If so it'd be a really-unique radio.

The IFT-cans appear to be single-tuned, which is really not what I'd have expected if serious selectivity was to be expected.

And I don't see a BFO control or a crystal-phasing conrol, so it doesn't really look like any form of serious "Communications" receiver.

How very strange, but fascinating nevertheless! I look forward to further revelations.

[m0cemdave]

British Monomarks are still in operation, and they still provide "virtual office" facilities and a "BCM-" London address for companies.

They also provide a Poste Restante service for individuals - I used it many years ago, when I was travelling abroad with no fixed UK address.

Another thing they provided (maybe still do) was a secure "if found, please return to..." labelling service for lost keys and luggage, avoiding the need for personal addresses on such items. My grandfather was one of the first users of that system in, I think, 1924. I have an old trunk somewhere that still sports a label with his old BM- address!

[G6Tanuki]

British Monomarks are still in operation, and they still provide "virtual office" facilities and a "BCM-" London address for companies

I remember that back in the Pirate Radio era [1965-onwards] many of the companies who advertised on said stations quoted a "BCM Box XXX" address for correspondence.

"BCM BRFM" would be familiar to longterm Radio Caroline aficionados.

[allan]

It does have double tuned IF transformers OM (see the pictures) and one tuning condenser is for HF bands and the larger for MW/LW.
The mention of a TRF stage might imply this could be used as a BFO?

It's possible the surplus coils used in the set were originally suited to either a large or small tuning condenser and to cut corners the designer used both.
The picture I show of the underside of the chassis may be clear enough to trace the circuit of the missing valve (bottom left corner). This socket is mounted on spacers, I guess so the valve top cap doesn't foul the underside of the magic eye. Was it an X61M or a KTW63?
Allan G3PIY

[Synchrodyne]

From the available description, the TRF facility was used for quality reception of local MF stations. At the time there was a viewpoint that in this role, the TRF was better than the superhet, and that the infinite impedance demodulator was better than the diode type. Neither proposition was necessarily true in an absolute sense, although it might have been easier to achieve the desired bandwidth (±12 kHz in this case) with a TRF, and the desired low level of distortion with an infinite impedance demodulator. On the other hand, there have been some excellent wideband AM tuners that were both superhets and which used diode demodulators.

Another manufacturer who offered dual-mode, that is superhet and TRF, AM tuners was Lowther, with its DT-series. As far as I know “DT” stood for dual tuner.

The Moreton Cheney receiver appears to have been designed to a similar overall target as the contemporary Peerless 1546, which I think was also short-lived. The latter though did include a crystal filter in the IF strip and a BFO on the “communications” side. It also had a four-gang front end, albeit with a double-tuned bandpass input and a single RF stage rather than the two single-tuned RF stages that was “normal” in communications receiver practice.


Cheers,

[allan]

One of the annoying things about my example of the receiver is that several knobs which would have been labelled are missing. Those that remain have clear markings on them, Tune, Wavechange (1-5), Var Select (1-6), QAVC/Radio/Gram. The others are pots, I guess those missing would be Volume, maybe Tone, plus one other.. maybe RF gain, plus one at the rear (maybe to do with Gram preset volume?).
One control operates two pots ganged with brass gears (RF gain?).
I've cleaned the top of the chassis and derusted things so it now looks half respectable.
I understand it uses two 6J5 triodes as push pull output. That's new to me.
I suppose the design was made around the cheapest, most common government surplus parts?
The TRF function might be switched in by the Var.Select control. The DST100 which I have has a different method of broadening audio response.. this is by switching from double to single superhet.
I wonder if this Moreton Chayney set is the only surviving example?
Allan G3PIY

[Paul_RK]

I wonder if this Moreton Chayney set is the only surviving example?

It wouldn't surprise me, I've come across the odd reference to the company and its Silver Dragon, commencing probably nearer 50 than 40 years ago, but I've never seen so much as a mention of a still existing set, and judging by its headquarters the enterprise barely made the transition from demob pipedream to going concern. The late Geoffrey Dixon-Nuttall wrote on several of the most ambitious domestic valve receivers for early issues of The Radiophile, and I'm just about sure he would have described this set if he had ever met one. Fascinating to see it at last and put some flesh on the bones of the Wireless World publicity, and if there are one or two more survivors around they're more likely than not to be known to, if not actually in the hands of, members here.

Paul

[allan]

I wish I could identify the original owner Paul.
It came in a job lot with a N.O.S. T1154 still in its packing case, an unmolested R1132A and a huge power supply/modulator still fitted with one of two KT66s, and a pair of EF37s. I asked the seller where it came from and she said her late father in law took the stuff in exchange for a plastering job a long time ago. This would have been in the Ferndown or Wimborne area and I suspect the stuff may have been found in a garage when new owners moved in. As a rough guess this may have been circa 1961 so we'd be looking for a silent key in Dorset around 1960.
Allan G3PIY

[Synchrodyne]

Re the controls, it seems likely that the change from superhet to TRF was done by the variable selectivity control. The brief description in WW 1946 October includes: “There are six degrees of selectivity, with bandwidths of 5 to 24 kc/s, the latter given by a T.R.F. circuit…” From that, we could infer that the 6th position of the selectivity control did the changeover to TRF. The other 5 positions may have varied IF transformer coupling by tertiary coil tappings (perhaps also with gain adjustment resistors somewhere in the mix), but the underside view shows a couple of what might be cams on the variable selectivity control shaft, which if so would point to mechanical coil position adjustment within some of the IFTs.

The WW item also indicates that there were independent bass and treble controls, which would thus account for two of the control knobs and shafts.

Thus the front panel rotary controls would likely include:

Volume
Bass
Treble
Wavechange
Tuning
Selectivity
Input selection (gram, etc.)

My best guess is that the two left-hand-most controls are bass and treble (although actual order unknown). And that the volume control is that just to the right of the tuning control. The use of two pots in tandem for volume controls is not unknown, although right now no specific examples come to mind.

The rear-mounted preset might be an IF gain control. Such were sometimes used on domestic-type receivers that had an abundance of gain. For example, the Chapman S6BS tuner had this facility, on later iterations at least if not from the start, and Dynatron added it to the T99 (as the T99A iteration, I think). As best as I can tell from the schematic, the Ekco A182 integrated receiver (which unlike most of its contemporaries had two IF stages amongst several unusual features) had the facility to preset two levels of IF gain.


Cheers,

[allan]

I think you are right om.
I'd forgotten the separate bass and treble controls.
I've added a few more findings which you can take a look at incuding the action of the cams. The DST100 used sets of fixed capacitors to broaden the IF response but moving dust cores is another option. I wonder why the designers didn't just add extra capacitors as it would have been a lot cheaper? Because of general aging their method looks a bit iffy but I'll see if I can sort it out later.
Currently I've been repairing some damage to the underside caused by rough handling including straightening of various aluminium brackets that resulted in seized controls. At the end of the day I don't think the extra bandwidth will be of much use because my SDR shows the true width of modern broadcast stations that I can hear to be no more than 14KHz to 15KHz max (+/-7KHz). Still, I'd like to return the old set to its original spec.
I shall attempt to draw a block diagram of the set to identify the purpose of all the valves then see if I can determine the circuit diagram. What worries me is the huge number of potentially leaky condensers although I might be able to get the thing going before dealing with them.
Allan G3PIY

[Keith]

Alan,
You may find that those Sprague metal cased capacitors are not leaky. They look the same type as those in the E.K.Cole manufactured 19 set which I have found to be absolutely fine, even after 70 odd years. The waxies, however, will be a different story!

[allan]

You may be right Keith. I found much the same years ago re those Spragues.
I'm just tackling a really horrible job which are the two IF transformers that carry the bandwidth adjustment for changing their tuning.
One has a plastic tube that allows a change of coupling but the other has a dust core that changes coupling plus inductance.
There's verdigris, failed glue and rusty screws fitted with rusty locknuts to deal with. Wear has resulted in the moveable parts seizing and add to that accessibility problems and my dodgy eyesight.. it's not easy.
How the radio assemblers managed in 1946 I don't know. They would not have had a spectrum analyser.. but maybe a wobbulator?
I've just added some sketches.
Allan G3PIY

[HamishBoxer]

Certainly a Wobbulator,Chas Miller always used one.(Cossor I belive).

[stevehertz]

I'm of the mind that the late Chas Miller's first job in the radio business was in a repair shop in that vicinity - within a few hundred yards I reckon (I know Stafford quite well). Alas it's too late for Chas to comment or be consulted now.