Old Radios, Classic Radios, Radio Restoration - Page 5 - Canadian TV, Computing and Home Theatre Forums
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post #61 of 80 (permalink) Old 2014-12-30, 05:55 AM
 
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Thanks much, Exdilbert. I suppose improving the RF end - at least upstream of heterodyne stage - doesn't introduce distortion but does add sensitivity and selectivity.

Given the commercial imperative to be loud, near-hopeless that broadcasting will play nice. But CBC-FM in Toronto at 94.1 (I will never remember if that has the totally stupid name of #1 or #2) has excellent fidelity. Likewise for HD, PBS stations (such as in Buffalo, 94.5), provide sound that's about all I could ask for.

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midtown Toronto, DB4e, 60ft RG6, 8dB distr amp
FM: Sony STSA-50ES, Wine.6065, 40ft RG6
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post #62 of 80 (permalink) Old 2015-02-16, 07:31 PM
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antique radio reception

I'm restoring a 1940s Canadian Marconi radio, model 201A. The caps and tubes have all been replaced. Radio works great--beautiful sound. Reception is good throughout the house. But the best reception is in the basement, where the eye tube closes completely, indicating a strong signal. The antenna consists of nothing more than 2 metres of cloth-covered wire hanging out the back of the chassis. I don't know much about electronics and communication, but I've been wondering why the reception is best in the basement. Is it the presence of conducting material, i.e. furnace ducts, plumbing, electrical wiring? Most of the basement is above grade.
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post #63 of 80 (permalink) Old 2015-02-19, 01:30 AM
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If the antenna is close to a furnace duct or some wiring, it could be picking up signals from those conductors due to inductance coupling. A really good AM band antenna would be about 100' long or more so 2m of wire is sufficient but not optimal. Some AM radios once came with a wire and a clip for connecting to metal object like furnace duct or even electrical wiring. I wouldn't recommend doing so since it can be dangerous. It was dangerous then but safety standards were much lower.
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post #64 of 80 (permalink) Old 2015-02-19, 06:19 AM
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The reason it may work better in the basement is most likely related to man made noise sources in other parts of the house that may be much weaker or not present in the basement at all. In other words, it's not as likely that the signal is actually much 'stronger' down there, vs the signal being 'cleaner' because the noise floor is lower.

ie Noise from cheap electronics, light fixtures with CFL bulbs, dimmers, so on. None of these sources existed when the product was designed and
will raise havoc even with modern AM radios.

I had to google it to see what it looked like etc. I am gonna go out on a limb and say your radio is from the 1930's and not the 40's.
Because most if not all 1940's and later tabletop radios came with a built in Loop antenna for AM BC Band, and the frontend would have tuned circuits that relied heavily on the inductance of that Loop Antenna for optimum performance. I don't see any loop antenna in any of the pictures I can find.
Does the set have a ground terminal anywhere??? Usually it's a fahnestock clip... If so, try grounding it to a cold water pipe, and your reception may improve a little bit more.


Edit: just saw one reference that says circa 1939....Makes sense

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post #65 of 80 (permalink) Old 2015-02-19, 01:42 PM
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Wartime Gaps in product availability

Quote:
Originally Posted by majortom
I am gonna go out on a limb and say your radio is from the 1930's and not the 40's
Yep, it is handy to remember that almost none were made in the U.S.A. between 1942-45 and hardly any in 1946 as industry resumed market manufacturing. In Canada and the British Commonwealth you can rule out 1940-41 as well but you'll find 1939 products. Some European brands didn't get up and running again after the war until the late 1940s, and the Japanese consumer electronics industry really didn't show up much in North America until the early 1970s, well past the vacuum tube era.

In the 1970s there was a worldwide shortage of vacuum tubes, so military organizations like Canada's navy ironically had to source them from Czechoslovakia and other Warsaw Pact countries! That issue turned into a very highly motivating factor for western military organizations to finally getting rid of all their tube-type electronic systems that were still being used.
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post #66 of 80 (permalink) Old 2015-02-19, 02:03 PM
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Transistor radios from Japan were popular as early as the mid-1960s. That's when Sony started making their portable transistor sets. Dozens of imitators soon followed. Tubes were still common in the popular kitchen tabletop radios and in TVs until the late 1960s. I suspect that was due to cost (those later model tube radios had incredibly cheap designs) and the difficulty in replacing some tube based circuits, like the flyback transformer circuit in TVs. It's also a big factor in the decline of the NA electronics industry. Obsolete factories that relied on making tube radios and TVs closed down as cheap, modern transistor sets from Japan flooded the market.
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post #67 of 80 (permalink) Old 2015-02-19, 10:25 PM
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Something else interesting about wartime...
I am told German Immigrants were required by law to bring their SW capable radios in to local service shops to have the SW Bands disabled.
For fear they could be in contact with or listen to propaganda from the enemy...

Modifications like removing a coil from a SW tuned circuit were done and notes typically left inside by the technician doing the work.
So, if ya ever get a hold of an old radio from that time and SW bands don't work, that is always a possibility... ie that it was never reverted after the war was over.

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post #68 of 80 (permalink) Old 2015-06-20, 05:05 PM
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Bendix 753 AM Clock Radio

Not very interesting, but finished up this tube set today. I've had it in the shop for a few years.
Holding it up was a worn gear in the clock movement. Finally found
another basket case chassis at a reasonable price to pillage the clock movement from. The basket case also had a complete set of knobs.
Keeps good time thus far and the alarm works. Has a spigot for another appliance in the rear that will energise with the alarm.
I think it is from 1953.





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post #69 of 80 (permalink) Old 2015-06-21, 04:06 AM
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I'll bet its nice and warm after it's been on awhile.
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post #70 of 80 (permalink) Old 2015-06-21, 07:57 AM
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nowhere near as warm as the CPU in my laptop
Check out post # 8 and you'll see what it looked like when I found it.

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post #71 of 80 (permalink) Old 2015-06-28, 06:50 PM
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Next Radio project... it's a Truetone D-2026 from ~ 1951... these were sold in Western Auto stores back in the day.
I had to wing it to restring the dial cord, as no diagram is available for this one.
FM Works, AM doesn't.. Not a bad radio though...It's not a hot chassis, has a Power transformer.
I think this one has a severe case of Silver Mica Disease, so we'll see if I can restore without damaging the IF Transformers.
https://db.tt/wngNLCYz
https://db.tt/NYfXH54p

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post #72 of 80 (permalink) Old 2016-01-24, 01:04 PM
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RCA R-37-P that someone gave to me. From ~ 1933, missing a knob, and the cabinet's in pretty rough shape. Tubes were bought ~ 1936, as there's a sticker on all but one that was missing, with presumably the original owner's name and address on it. Or maybe that's a sign of the last time it was serviced?? The missing one was a 58 tube. IF Frequency is 175 KHz. The 'P' in the model stands for Police, meaning it has
a band switch to tune Police Band, which back then was 1400 - 2800 KHz.
Replaced all of the caps and it fired right up.





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post #73 of 80 (permalink) Old 2016-01-25, 02:10 PM
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Quote:
Originally Posted by majortom
it has a band switch to tune Police Band
Popular back then with the Al Capone types, I'm sure!
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post #74 of 80 (permalink) Old 2016-01-25, 06:50 PM
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yeah, one thing ya won't see in old movies is what a mobile rig with a two way radio antenna looked like back then.

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post #75 of 80 (permalink) Old 2016-01-25, 08:04 PM
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White Heat (US, 1949) has some good sequences regarding an early radio-assisted pursuit through Los Angeles. Back on topic.
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