Cossor 'Melody Maker 501'

[Refugee]

If I want a set to look authentic a modern resistor can be dipped into something that will fade the paint such as old engine oil.

[Kalee20]

It's not my favourite radio - it's somewhat insensitive; the AVC system could have been better; oscillator/ RF tracking could have been much better with more trimming. Mains cable anchoring is as you say, leaving something to be desired. But there's a good-sized loudspeaker, and sound quality is good.

It's also easy to work on, and the chassis comes out without any drama.

Incidentally, I thought the 500 was thye woodie and 501 the Bakelite?

[pwdrive]

I think those larger sized dogbones are around 2 Watts or so? they did some big fat ones as well, about 12 mm in diameter, my old Marconi CR300 has one of them in the heater circuit I seem to recollect, I guess those ones are nearer 5 Watt.

Lawrence.

Just checked in the CR300 book of words, the large dogbone is 120 ohms but no wattage rating is given.
However the CR300 uses a 24-28 volt heater supply, (from a seperate power supply) the valves are .3 amp heaters except the sound output valve (6V6G) it's heaters are .45 amp, that valve is in series with two KTW61's and a DH63 so that means the last mentioned valves need the 120 ohm resistor across them to give a current of .45 amp to match the current of the 6V6G heaters, this means the dogbone needs to be able to dissipate 2.7 watts, so as a guess I would say it is rated somewhere between 3 and 5 watts.
Just to avoid any confusion the total number of valves in the receiver are arranged in a twin series parallel arrangement ie: four 6.3v heater valves in each series circuit the two series circuits then being connected in parallel.

Lawrence.

[Yorkie]

It's not my favourite radio - it's somewhat insensitive; the AVC system could have been better; oscillator/ RF tracking could have been much better with more trimming. Mains cable anchoring is as you say, leaving something to be desired. But there's a good-sized loudspeaker, and sound quality is good.

It's also easy to work on, and the chassis comes out without any drama.

Incidentally, I thought the 500 was the woodie and 501 the Bakelite?

Thanks for reading the thread and for your comments - I'd echo your sentiments.

Re the sensitivity, the data sheet does state:

Quote:

Frame Aerial: 'The built in frame aerial, mounted on the back of the cabinet, is only intended for local station reception. For more distant listening a normal aerial and earth should be used'.

End quote.

It does receive a few stations on the frame aerial - in these parts, 'Magic 1161', 'Absolute Radio' and Radio 1 all at good strength. However, with an aerial plugged in it really comes to life on all bands. (My workshop aerial consists of a 60 ft wire fixed to the garden fence about 6ft off the ground. It works well - height makes no appreciable difference on LW & MW - even an aerial 10 Metres above ground is only a 20th of a wavelength high on 200 Metres (if 'high' is the right term for 1/20th of a wavelength!. On 1,500 Metres it's only 150th of a wavelength high and most of what RF is received is ground wave rather than sky wave).

Unlike many sets of the era, it does have the merit of being AC only, with a mains transformer.

You're correct about the 500 being the more expensive 'woodie' and the 501 being the Bakelite one. In some of my posts I mistakenly referred to this Bakelite one as the '500' so I've edited the posts to remove any confusion.

I don't think that the early 50s was an illustrious time for the British radio industry, or any British industry come to that - cars, motorbikes, shipbuilding or whatever. Still using 1930s machinery clapped out by the war effort, still the same labour-intensive techniques producing shoddy goods in short supply ('Export or die'), for which customers had to wait in line, and in many cases, were the subject of ration books. Full employment, an often workshy labour force, under-capitalisation, restrictive practices and inept, complacent management, leading to an 'us & them' ethos in which strikes became endemic. Not fertile ground for innovative radios or much else for that matter.

Remarkable how Germany and Holland got back into peacetime production and by the mid 50s, names such as Grundig and Telfunken started appearing in UK shops, offering '3-D sound' and 'hi-fi' at a price. I know that those large glossy radios with their long dials and piano keys aren't to everyone's taste, but when viewed alongside the lacklustre drab sets that British firms were turning out, to my eyes back then, they were quite something. But in fairness, for dedicated short-wave listeners who could afford them and could find the space to house them, there were Eddystones.

Then TV came along!

Sorry for the irrelevant socio-economic reminiscences - I'm showing my age again - I was already aged 11 when this set was coming off the production line.

[singlepentode69]

I am about to embark on the restoration of one what wattage resistors did you use as I will probably have to stock up on these .at the moment I have run it up on the lamp limiter and no problems and there is sound from the speaker but no stations as of yet.
Regards
Robin

[Yorkie]

I am about to embark on the restoration of one what wattage resistors did you use as I will probably have to stock up on these .at the moment I have run it up on the lamp limiter and no problems and there is sound from the speaker but no stations as of yet.
Regards
Robin

I only replace resistors if they're more than 20% out of tolerance, and usually use 2 Watt metal film ones as they're compatible in size to the original 1/2 Watt carbon composition ones. Modern 0.6Watt resistors just look so puny and out of place, even though they're out of the way under the chassis. I mostly get my resistors from Spiratronics as they're inexpensive (about 10p each), but the range is a bit limited. (Go on their website - Spiratronics e-bay shop is paradoxically more expensive!).

You can also get them from the likes of Cricklewood and Farnell, and for the more ambitious, full sets from Justradios in Canada, which I'ver never personally used. The snag with the sets is that they're the full E24 range, with many values never destined to be used.

Incidentally, this particular set which was the result of this thread was given as a housewarming present for a work colleague of my daughter-in-law, who is delighted with it and uses it in her kitchen daily, where it performs very well.

Good luck with the restoration Robin!

[singlepentode69]

Thank you for the info I will try them ,I don't fancy getting a full set as we had a full resistor set in the test dept at quad and they tautly got used they were binned in the end I had no use for them .i only got into radios after a seeing a programme on Gerry wells and was hooked ever since.I am hoping the transformer will last as I have heard dreadfully things about these way impregnated ones.
Regards
Robin

[Aerodyne]

Spiratronics also has small differences between its offered stocklist on Ebay and its catalogue listing. I found this to be the case when I wanted a small transformer. Present on Ebay, not in catalogue. I suspect the reason why they charge a little more on Ebay is to cover the costs of Ebay and the Paypal charges. Useful firm, though.
I own a 495 model. Same cabinet in Bakelite but the moulding around the scale and LS aperture is built-in to the bakelite and is simply sprayed cream to separate it visually. Personally I much prefer it to the rather delicate physically separate moulding on the later models.
Like you, David, I'm mystified as to why the awful retaining valveholders were ever used. Of course originally the valves designed for these devices were made with a metal base and only later were the all-glass types brought out, probably made with cost saving in mind.
I also am with you on the rather inelegant stepped cabinet design, with its echoes of austerity. Not one of my favourite sets.
Tony

[Yorkie]

Like you, David, I'm mystified as to why the awful retaining valveholders were ever used. Of course originally the valves designed for these devices were made with a metal base and only later were the all-glass types brought out, probably made with cost saving in mind.
I also am with you on the rather inelegant stepped cabinet design, with its echoes of austerity. Not one of my favourite sets.
Tony

As to Spiratronics and their 2 Watt Metal Film resistors, The higher values are mostly of interest to us, and there are a few gaps in what we might want, but here is the full range of 2 Watt Metal film that Spiratronics stock, reasonably priced at 11p each. (They're cheaper for 10+ each - I've just bought 9 lots of ten, which inc VAT and £1.24 p&p came to £9.59. They arrived next day):

1R 100R, 1K, 100K, 1M
2R2, 2K2, 220K
3R3, 33R, 330R, 33K, 330K
4R7, 47R, 4K7, 470K
68R, 680R, 6K8, 680K

http://spiratronics.com/resistors-and-po...ors.html#1

The stock other types of resistors, such as 5 Watt wirewound ceramic axial ones, but curiously, the pic they show is of a radial one, albeit not the ones listed:

http://spiratronics.com/resistors-and-po...stors.html

Lots of other components including ICs, caps diodes etc.

Nice outfit.

As to those ghastly wire retaining rings, I can only assume that they were war surplus, and as you say Tony, were originally intended for use with metal based valves. I can see how in military equipment where vibration over rough terrain might just shake valves loose, but I wonder how many DAC90A 'doer-uppers' have been caught out and smashed the pips off valves. Even with the springs removed and discarded the valves take some removing.

As to brown Bakelite sets looking austere, you and I are old enough (me more than you I must add!), to recall when Bakelite was looked upon as an inferior 'mass produced' utilitarian alternative to wood and that's reflected in the prices of models which were sometimes offered in alternative wooden or Bakelite cabinets, in which the wooden cabinet was more expensive.

I've said before that the DAC90A is my least favourite set because we had one sat on the sideboard for years from about 1948 - 58. The only memories that the DAC90A evokes for me is ration books, queues, shortages, power cuts, dried egg powder, cod liver oil, MoF Orange juice, and being made to wear short trousers till I was fourteen because long trousers needed more clothing coupons.

It's a generation thing, and I readily concede that many do not share my view and view the DAC90A s an 'iconic' radio - even their favourite set. Though the DAC90A isn't the best set for newcomers to cut their teeth on, they're so commonplace due to hundreds of thousands being put out on rental during their long production run that it's almost inevitable that almost anyone and everyone with any interest in radio will have had one or more at some time or another.

Almost every film or play on TV or in the theatre set in the post-war years will have a DAC90A on the sideboard. I can't get away from them - we saw a delightful little play at a theatre last Friday night at Barton on Humber, which is now touring, entitled 'Leave Hitler to me Lad' (set in 1952). Sure enough, a DAC90A featured. There it is - 35 Secs into this clip:

http://www.duckegg.org.uk/productions/leave-hitler-tour

Ho hum - maybe they'll drop it before the tour ends?

Rambled Yorkie, pedantically.

[singlepentode69]

I have started restoration today but i am stumped on what to replace the two 0.005 capacitors with they seem to be the only ones i did not have in stock and was not to sure what to substitute them for.
regards
robin