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 Post subject: Re: USSR 1969 RADIO PROJECT
PostPosted: Jul Thu 12, 2018 12:49 am 
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Location: Ashhurst, New Zealand
By 'lively' I assume you mean there is plenty of noise in the speaker when you wind the volume up full. Most of the noise in any radio will come from the frequency converter and so we get back to your initial problem - is the oscillator working? Without this, there will be no conversion of the signal frequency to the intermediate frequency. The easy check for this is to get another radio, tune it to a blank spot somewhere around 1500kHz, turn the volume up to hear the background noise, hold it close to the Spidola which you tune up and down around the broadcast band MW 1050kHz mark on the dial - you may have to guesstimate a bit as you haven't got a dial to read. You should hear your other radio go quiet as the oscillator sweeps through about 1500 kHz but if you don't - then the oscillator is not going.

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 Post subject: Re: USSR 1969 RADIO PROJECT
PostPosted: Jul Thu 12, 2018 1:56 pm 
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Posts: 170
I will explore this further. 2 days ago I set the VEF on MW and used a Bush. This was trial and error but I could hear reaction one point of the dial. You can also hear the scale lamps switch on and off. A bit like morse. Anyway, good idea. I will try and eliminate the oscillator first. The voltages on T1 are now correct.


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 Post subject: Re: USSR 1969 RADIO PROJECT
PostPosted: Jul Thu 12, 2018 9:34 pm 
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Joined: Jan Thu 01, 1970 1:00 am
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Location: Haledon, NJ, usa
10.7Megahertz wrote:
I will explore this further. 2 days ago I set the VEF on MW and used a Bush. This was trial and error but I could hear reaction one point of the dial. You can also hear the scale lamps switch on and off. A bit like morse. Anyway, good idea. I will try and eliminate the oscillator first. The voltages on T1 are now correct.

Curious: .. what is a "scale lamp" ?
... is that the "dial lamp"? ... if so why is it going on/off?

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 Post subject: Re: USSR 1969 RADIO PROJECT
PostPosted: Jul Thu 12, 2018 10:18 pm 
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Joined: Jan Mon 22, 2018 5:59 pm
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The scale lamps are triggered by a simple push contact switch at the front. Originally the bulbs didn't light due to grime. They flash on and off often as I lay the radio face down. Given the need to often pull the board away, I extended many wires so there is more play.


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 Post subject: Re: USSR 1969 RADIO PROJECT
PostPosted: Jul Thu 12, 2018 10:27 pm 
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I live on a small fibreglass boat which I restored over 4 years. There is not a lot of space so I place any radio on the bed and kneel. In the case of a high voltage tube set this is a bit unorthodox. On one occasion a 1947 AC DC tube receiver almost caught fire when an aged mains filter cap melted. I pulled the plug just in time and the radio was then restored and saved.


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 Post subject: Re: USSR 1969 RADIO PROJECT
PostPosted: Jul Sat 14, 2018 12:45 am 
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majoco wrote:
By 'lively' I assume you mean there is plenty of noise in the speaker when you wind the volume up full. Most of the noise in any radio will come from the frequency converter and so we get back to your initial problem - is the oscillator working? Without this, there will be no conversion of the signal frequency to the intermediate frequency. The easy check for this is to get another radio, tune it to a blank spot somewhere around 1500kHz, turn the volume up to hear the background noise, hold it close to the Spidola which you tune up and down around the broadcast band MW 1050kHz mark on the dial - you may have to guesstimate a bit as you haven't got a dial to read. You should hear your other radio go quiet as the oscillator sweeps through about 1500 kHz but if you don't - then the oscillator is not going.

I had to struggle to resolder some wires that broke off the busbar. Moving the board about tends to weaken joints on the spade terminals. Even so they should still ideally resist movement. So I tried to really get stronger joints and tried different wire. I then tested T1 the oscillator and it is now closer to the text. The collector is at nearly twice the voltage referenced from point 1 but exact to spec from another ref point. If I play my Bush tranny on a station it is possible to tune the VEF till it swamps. I think eventually I will get the radio to work but it has been demanding. I ideally needed slightly thinner wire to solder.


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 Post subject: Re: USSR 1969 RADIO PROJECT
PostPosted: Jul Sun 15, 2018 12:34 am 
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Those spade terminals have caused me major soldering issues. I have to move the board about a lot so the wires tend to move about. The movement causes the solder joint to weaken. I was unhappy with that as I figure a good solder joint should hold firm. I am using wire that's about twice the diameter of the original so I have to use more solder. I had the odd occasion where the solder bridged to another spade. In such cases I use a wire cutter to pinch off dry solder. Actual pcb soldering is easy for me but the spades really seem to not take the solder. Even after scraping and cleaning alcohol. A friend urges me to try flux as he says it helps a lot. So, T1 oscillator voltage today tested to spec. This is good as there was originally no volts. With another radio set to mw I got faint whistling when tuning the VEF at one specific point. So probably.it does oscillate. Next stage is to focus on any more wiring faults and install new capacitors.


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 Post subject: Re: USSR 1969 RADIO PROJECT
PostPosted: Jul Sun 15, 2018 12:54 am 
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Joined: Jan Thu 01, 1970 1:00 am
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Location: Haledon, NJ, usa
10.7Megahertz wrote:
Those spade terminals have caused me major soldering issues. I have to move the board about a lot so the wires tend to move about. The movement causes the solder joint to weaken. I was unhappy with that as I figure a good solder joint should hold firm. I am using wire that's about twice the diameter of the original so I have to use more solder. I had the odd occasion where the solder bridged to another spade. In such cases I use a wire cutter to pinch off dry solder. Actual pcb soldering is easy for me but the spades really seem to not take the solder. Even after scraping and cleaning alcohol. A friend urges me to try flux as he says it helps a lot. So, T1 oscillator voltage today tested to spec. This is good as there was originally no volts. With another radio set to mw I got faint whistling when tuning the VEF at one specific point. So probably.it does oscillate. Next stage is to focus on any more wiring faults and install new capacitors.

Solder with rosin core ... and/or extra flux

https://www.radioshack.com/products/ros ... paste-flux

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To be a man, Be a non-conformist, Nothing's sacred as the integrity of your own mind.
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 Post subject: Re: USSR 1969 RADIO PROJECT
PostPosted: Jul Wed 18, 2018 5:43 pm 
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Joined: Jan Mon 22, 2018 5:59 pm
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I worked on receivers normally so old that ferrite aerials were never to be found. And the aerial and oscillator coils were far simpler to switch in MW, LW and SW (if SW was included).

On this set the ferrite aerial was really pretty "weathered". A fair few loose, fine wires.


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 Post subject: Re: USSR 1969 RADIO PROJECT
PostPosted: Jul Sat 21, 2018 5:51 pm 
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Joined: Jan Mon 22, 2018 5:59 pm
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I was forced to zoom in on the RF systems of these modern sets. I've been very busy though all round doing psychology work and recording music again. Anyway I downed the soldering iron and studied the layout for the aerial and oscillator windings. So now I know specifically where the MW winding is. My job is to partly rewind the ferrite coils and trace the winding. It seems odd how dilapidated the wiring was and the windings were snapped off in some points when I first opened it. I had to use more than one schematic as often the writing to mark the windings was too faded. I haven't forgotten either one of the IF cans only tested 1.5 volts as opposed to 8 or so on the others and that struck my attention. Yes, progress here is slow but I'm bogged down with psychology at least 5 days of the week.


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 Post subject: Re: USSR 1969 RADIO PROJECT
PostPosted: Jul Sun 22, 2018 8:29 pm 
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Joined: Jan Mon 22, 2018 5:59 pm
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Thoughts or experience winding ferrite bars? I need to redo what I attempted the first time. I believe the thread itself is normally scraped with a razor at the tip. The MW winding I just need to tidy up and wax a bit. The MW coil isn't bad but a couple of the others are messy. Ferrite bars are new to tube hobbyists. This particular one was the weakest link in the set and broken threads originally evident. Once done I ought to be able to trace the MW winding to T1. At least one other winding really ought to be redone. I have similar work to do with a tube radio where broken thread is se en around mounted windings.


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