Pennine Amplifiers 'Scout' Radiogram.

[Joe]

Ouch! What have I done to deserve that? George Formby's more my style.

I have got a 78 of 'The Teddy Bears' Picnic' which is the traditional test disc. First I've got to sort that idler out. The rubber is so hard, in fact if I didn't know it was rubber I'd think it was some type of hard plastic, that there's no chance of turning it inside out.

Cheers

Joe

[Yorkie]

Ouch! What have I done to deserve that? George Formby's more my style.

I have got a 78 of 'The Teddy Bears' Picnic' which is the traditional test disc. First I've got to sort that idler out. The rubber is so hard, in fact if I didn't know it was rubber I'd think it was some type of hard plastic, that there's no chance of turning it inside out.

Cheers

Joe

Well we are off to Leeds on Weds night Joe to see the Ukulele Orchestra of GB, but their style of playing is as far away from Goerge Formby as a tangerine is from a turnip, or punk from Pavarotti!

Just a thought as to the idler - is there any possiblity that an 'O' ring would do the trick or is the idler a solid disc, rather than a 'tyre' on a pulley, and with a square edge to it rather than a circular section as an 'O' ring would be? 'O' rings come in many sizes - I've got a kit of 34 sizes ranging from 3mm ID/6mm OD (1.5mm section), to 50mm ID/57mm OD (3.5mm section).

I guess you perhaps won't bother too much with the record player side of things because you're very unlikely to use it. Interesting bit of kit though, that would have cost a princely sum in its day. Amazing how many small firms such as Pennine, and Graves at Sheffiled got into radio production up against the 'big boys' which got bigger all the time through amalgamation.

[Joe]

I've just been turning the idler down a bit. This has got rid of the dink where it had been pressed against the motor shaft for years but as it's so hard it rumbles like hell when it's going 'round.

Putting a rubber band around it gets rid of that but it very quickly flies off so I'll see about gluing one in place.

The radio side gets ever odder. This morning I thought I'd see what the alignment was like. I didn't know what the IF should be so hooked it up to the Nombrex and swept around the 450-470 kc/s area. Not a peep was heard. More or less by accident I found it at 100 kc/s. The first IFT primary was about a quarter turn out and and fixing that has improved things a surprising amount. Frankly this beggers belief so I'll check it again with the Advance when I've cleared enough space to rig it up.

- Joe

[Yorkie]

Quite a lot on Wiki about the history of IFs and the development of the superhet Joe.

Commonly used intermediate frequencies:

• 110 Khz was used in Long wave broadcast receivers.
• FM radio receivers: 262 kHz, 455 kHz, 1.6 MHz, 5.5 MHz, 10.7 MHz, 10.8 MHz, 11.2 MHz, 11.7 MHz, 11.8 MHz, 21.4 MHz, 75 MHz and 98 MHz. In double-conversion superheterodyne receivers, a first intermediate frequency of 10.7 MHz is often used, followed by a second intermediate frequency of 470 kHz. There are triple conversion designs used in police scanner receivers, high-end communications receivers, and many point-to-point microwave systems.
• AM radio receivers: 450 kHz, 455 kHz, 460 kHz, 465 kHz, 470 kHz, 475 kHz, 480 kHz

Worth reading: http://en.wikipedia.org/wiki/Intermediate_frequency

Hope that's of interest.

[Joe]

I'll certainly have a look at that, David.

I've re-done it with the Advance and found it's actually 450 kc/s. It is now working very much better, at first I could only get Radio Sheffield and Absolute but can now get a few more stations and hear the interference between.

The idler repair worked but the cartridge seems to be shot as very little sound comes out of the amp and what there is is distorted. This doesn't greatly bother my as I have better uses for the PU sockets.

When I was given this I was told it was bought in 1939. The more I've worked on it the less I've thought this was correct. For a start two of the valves didn't come on the market 'til 1940 and the wiring on the deck is PVC. I finally settled the matter this morning as the speaker is dated 27 May 1949, which, coincidently, was my Mother's twenty-first birthday.

- Joe

[Yorkie]

Many pre-war radios had mains energised speakers, so if the speaker is a permanent magnet one, even if it didn't have a date on it, if it looked to be original, it's a safe bet that set is post war. If the dial has station markings, anything that has the Third programme on is post-1948. I believe that it wasn't until after the war that they could make larger permanent magnets with sufficient magnetism to power the larger speakers.

Many pre-war sets with Mains energised speakers have had them replaced due to the field coil burning out. The field coil consists of thousands of turns of fine wire (about 48SWG) and as it doubles as the smoothing choke carries all the HT. If for any reason (eg leaky caps), excess HT is drawn, the field coil can't cope and acts as a fuse! They can be re-wound at a price, but many restorers, or even service engineers when the sets were in normal daily use, prefer the easier, cheaper and quicker solution of fitting a PM speaker and putting a high wattage resistor across the smoothing/reservoir caps to substitute for the field winding.

[Joe]

I think I can now call this done.

   

The pick-up in the gramophone must have had quite a high output as modern devices connected too it were rather quite. I've therefore added an LM386 as a pre-amp and it sounds FANTASTIC as it's also improved the tone as well as raising the volume.

I know Dr Mark is interested in such things so I'll report that the speaker was made my Frederick Waterhouse Ltd, Edward Street, Dudley Hill, Bradford.

- Joe

[Paul_RK]

Nice job and not a model I've ever seen, I think I first heard of Pennine through adverts in some old copies of the Trader. Interesting about Frederick Waterhouse, I have - or did it leave? - a very small extension speaker produced by them, in red wrinkle finished metal case. Had always tended to guess that they'd bought in the drive unit, but perhaps not so.

I'll admit I didn't noticeably bat an eyelid at the thought of a 100 kc/s intermediate frequency, as something in the 110-130 kc/s range was very widely employed until 1935 when SW became a usual feature in domestic radios. I can't think of any instances of its post-war use, but smaller companies were quite often a law unto themselves (especially Yorkshire ones? Ambassador with their various odd circuit features, Pegasus marketing sets with dials calibrated only in kc/s in the middle 1930s...) and its resurrection for what I take to be a MW/LW only chassis didn't seem impossible.

Paul

[Joe]

I'd got a spare record deck in the loft so thought I may as well fit that.

   

I tested it with 78s and it seemed fine but when I put a 45 on it sounded blinking awful.

An FET on the input soon settled its hash and it now sounds very nice indeed.

   

- Joe

[Paula A]

I do approve of your choice of 45