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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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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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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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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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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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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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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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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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 Post subject: Re: USSR 1969 RADIO PROJECT
PostPosted: Jul Wed 25, 2018 8:45 pm 
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I suspect possibly one of my tube radio projects has some windings missing. I was swatting up on aerial and oscillator switching systems. Most here will know many tube radios had mounting boards for the windings. My tube radio does have a ferrite aerial too but the LW and MW windings are supposed to be mounted on a panel. Looking at the German schematic I just couldn't locate all the windings. The middle board had nothing. If this proves to be the case I will need to do what I can. This radio was one of those rarer sets where the tubes mounted on a pcb. It has a permeability tuner for the FM oscillator and a ratio detector.


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 Post subject: Re: USSR 1969 RADIO PROJECT
PostPosted: Jul Sat 28, 2018 6:57 pm 
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The MW winding was not in circuit. I rewound the last strands and tried regular sellotape to keep it from creeping. Last time I used wax. The hard part was scraping the coating off the strand ends. I am going to try and tidy up this part of the circuit. Many of the windings are untidy but the MW is my main priority. I will test it end to end once correctly wired.


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 Post subject: Re: USSR 1969 RADIO PROJECT
PostPosted: Jul Sun 29, 2018 1:48 pm 
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Hi 10.7MHz,

The MW antenna coil uses Litze-wire, that is a really fine stranded wire, 10x0.07mm.
For soldering you do not clean it mechanically!
Do a Google search on how to prepare Litze-wire for soldering!

Regards, Peter


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 Post subject: Re: USSR 1969 RADIO PROJECT
PostPosted: Jul Sun 29, 2018 7:05 pm 
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Well, it would seem people have struggled with this kind of wire. Lots of recommendations to be found. Ages ago I did my best to fix the ferrite aerial. I can now rate the work I did as not very good. Lack of experience on windings I suppose. Anyway today I made the MW coil neater and instead of hot wax I tried sellotape around the end thread, wrapped a turn or two. The MW coil has no break but good connections on the solder points is what I need to make. The thread is awful stuff. First a fabric insulation and then non conductive coating. Each strand very frail. As I said it could be my coils were not electrically in circuit
My view is the whole design of a rotating band changer was very vulnerable to age and wear and tear. Still, it keeps me occupied. Peter, how did you prepare this wire? I saw many suggestions.


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 Post subject: Re: USSR 1969 RADIO PROJECT
PostPosted: Jul Sun 29, 2018 10:19 pm 
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Hi 10.7MHz,

I used to burn off the insulation from the Litze-wire as described by "gusnaz" on "The RadioBoard Forums", in the fourth posting:
http://theradioboard.com/rb/viewtopic.php?t=1161

Be aware of the fire hazard if you decide to do it this way!

Regards, Peter


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 Post subject: Re: USSR 1969 RADIO PROJECT
PostPosted: Jul Mon 30, 2018 8:51 pm 
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I decided to disable the other windings for now and focus on MW. I had been getting dodgy meter readings for the MW coil but discovered the meter probes were poorly wired. Luckily I had some spare probes and now the meter is working. My MW coil shows it is in circuit. Although I already cleaned all the contact studs on the waveband drum, ohms tests a bit "wobbly" between stud and contact strip. In fact I am tempted to say I would rather have the old tube radio dial any day. In the former case the "springiness" of the strips weakens over time. So I can clean the contacts again, paying attention to the slight friction stains on the strips. And maybe trying to bend the tension back. Last point. Last point: this seems to be taking me some time so I am preparing to work on a tube radio. This also appears to have winding issues. Worryingly I have found no decent photos or advice for servicing Grundig style white push button knobs.


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 Post subject: Re: USSR 1969 RADIO PROJECT
PostPosted: Jul Mon 30, 2018 11:22 pm 
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An odd experiment. I tuned my 1969 Bush to MW and tuned in a strong station. I likewise put the VEF on MW. Tuning the VEF had no effect on the Bush at all. I tried the VEF on a range of drum rotations and then by chance, the Bush radio reacted wildly. The strong station was squashed. I looked at the drum and it was on 16 meters. This method lacks sophistication but it seems the VEF can oscillate. Possibly a fault could mean the 16 meters dial is not really 16 meters but it certainly caused my Bush to howl and whistle. The next routine thing I did was to let the drum slam into position from spring pressure. Doing this it momentarily seemed to try to burst into life. So my plan now is to stick to MW and go through the RF and oscillator coils and hopefully check the IF circuit. Maybe time I got a signal generator.


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 Post subject: Re: USSR 1969 RADIO PROJECT
PostPosted: Aug Wed 08, 2018 10:13 pm 
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I have grasped better the following. With radios such as this the collector should be the highest negative voltage. That is, red probe on chassis + and black probe on collector. After that comes base. Finally emitter should test the lowest. For me it helps to use the negative digits. However I am no longer totally sure the oscillator here is an tickler version. One coil seems to have a tap with coil connections to base, collector and emitter. The other coil is fed to the aerial coils. My plan is to test they all are in circuit and for now MW is priority. Soon as time allows I aim to do this. I now feel more familiar with the schematic.


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 Post subject: Re: USSR 1969 RADIO PROJECT
PostPosted: Aug Mon 27, 2018 10:28 pm 
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Update: I noticed medium wave gravitates around megacycles. If I recall correctly 55 meters on the schematic has a.mw designation. 13 meters is the highest frequency. Anyway I spent time swatting up on the use of signal generators as I lack a generator and was unsure of the various options. I find the HAM radio builders had plenty of ideas. Some used the 100 kilocycle spotter or sometimes the BFO. On tube sets.grid dip meters were available. Except many of the amateur sets had weirder IF frequencies. For example a double IF of five megacycles and 50 kilocycles. I can get by for now but I need a signal generator for the future. Sometimes vintage radio fairs offer better bargains than online. The amateur builders sometimes used the 455 KC domestic radios to tune them to the higher IF of the SW Ham receiver. Anyway the reading has helped. While I was at it I took a look at SSB as all the Ham guys used this and I wanted to learn how it works.


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