Well, OK. Remove another 2 turns and try again. Iterate untill the oscillator starts. When close to ten turns, procced at 1 turn removing each time. Reorder the remaining turns maintaining the separation between them more or less evenly.
Unfortunatelly this is a cut-&-try procces and you need a bit of patience. The tank must be slightly inductive at the Xtal frequency. How much? Really it depends on many parameters: tube gain, frequency, lay out, crystal characteristics, blah blah... So predict a result is amost impossible. This is why we start from an excess of turns and to remove them is better and easier than adding.
Unfortunatelly this is a cut-&-try procces and you need a bit of patience. The tank must be slightly inductive at the Xtal frequency. How much? Really it depends on many parameters: tube gain, frequency, lay out, crystal characteristics, blah blah... So predict a result is amost impossible. This is why we start from an excess of turns and to remove them is better and easier than adding.
No names are mentioned in the radio engineer's handbook (1943).
Ok, no problem. Will continue with removing.
At 9 turns right now... the beeper on my DMM oscillates for 1 second when I turn on with cold tube, this is also audible on the receiver... continuing...
https://en.m.wikipedia.org/wiki/Arm...Edwin H.,produce a frequency modulated signal.
I don't know if it has been used in commercial transmitter. There was another specially designed tube to get FM directly called Phasitron:
http://lampes-et-tubes.info/sp/sp006.php
Yes, it started with 9, was there with 8 and loosed alot of intensity with 7... I figured later that it happend while I had DMM's negative probe connected to the gnd and while I was twisting / moving the connector on DMM (to create loose connection basicly), beeper was oscillating constantly.
Also at 9 and 8 turns If I had negative probe connected and I would move positive probe close pass the coil, I could hear static on the radio, but at 6.7mhz... 6mhz is dead silent.
Also at 6.7mhz there is some noise, sounds like some interference and when I turn on the oscillator that noise gets attentuated a bit and as the tube warms up it's back to normal. But also plugging in soldering iron attenuates it... so this must be mains interference.
I have to be away from home by several hours. As it is unsafe to carry the phone with me because of thiefs, I will not answer you during this time.
If the osc continues refusing to start, try removing the 22pF paralleled to the crystal. It seems to be a hard-to-start crystal. Rewire the tank with 12 or 13 turns again and remove one turn each time until it start.
My apologies.
Once you find the proper number of turns, then stop removing turns and let it as it is. Thus make the start/stop test mentioned yesterday.
If the osc continues refusing to start, try removing the 22pF paralleled to the crystal. It seems to be a hard-to-start crystal. Rewire the tank with 12 or 13 turns again and remove one turn each time until it start.
My apologies.
Once you find the proper number of turns, then stop removing turns and let it as it is. Thus make the start/stop test mentioned yesterday.
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Ok, thank you will do as told. No problem. No need for apology, enjoy the day.
I had removed the capacitor. Now I can get -1.8v on the grid with gang almost all the way clockwise. Before that is -1.0v and after 0.7v...
To get -1.8v I must be very very presice, it usualy gets to -1.5v and requires very fine tuning after that.
But still nothing on the radio. My oscope with herz loop (only goes up to 200khz) will show 50hz with oscillator turned off. 50hz disappears when I turn the oscillator on.
Bulb with herz loop won't light up.
I had tryed to use big C (voltage on grid goes from -0,7v up to -1,4v) and had also tryed different gang (same result with small C as the first gang).
O-scope definately shows how it flattens the 50hz pickup if herz loop is in 0.5m radius of the oscillator:
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Before that is -1.0v and after - 0.7v... (negative, I wrote 0.7v first, but I can't edit anymore).
It works 🙂 problem was my radio... I for some reason it wont recieve under 6.6mhz anymore... I swapped crystal with 7.3mhz and now I get buzz on 7.3mhz...
With DMM connected to grid:
if I remove gang from full ccw position the buz stops and station starts playing.
Grid voltage with buzz is -0.90v and 0.72v without buzz
Without DMM connected I will get constant buzz, no mather the gang position.
I tryed to put 22pF cap back across the crystal, but it does not work with it in place.
Ok. I had returned. About 14Km in bicycle wheel #26 from home to dad and mum's and return.
OK to all. I see you could make it works. Crystals are capricious. Tubes too. So sometimes it is difficult to advance a result. Now make several tryes to shut down and on the oscillator to make sure it is capable of self start without touching the plastic gang.
How many turns got the coil?
The lamp will not bright with the small power from.a cristal oscillator. It will do with 1W or more of RF power.
Don't believe in the DMM. As I already advanced, they give erroneous readings with high levels of RF and it is normal.
Perhaps your radio is fine and the crystal has changed its resonant frequency from parallel to series now. And we removed the series trimmer. All this factor conducts invariably to a shift in the frequency.
OK to all. I see you could make it works. Crystals are capricious. Tubes too. So sometimes it is difficult to advance a result. Now make several tryes to shut down and on the oscillator to make sure it is capable of self start without touching the plastic gang.
How many turns got the coil?
The lamp will not bright with the small power from.a cristal oscillator. It will do with 1W or more of RF power.
Don't believe in the DMM. As I already advanced, they give erroneous readings with high levels of RF and it is normal.
Perhaps your radio is fine and the crystal has changed its resonant frequency from parallel to series now. And we removed the series trimmer. All this factor conducts invariably to a shift in the frequency.
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Off-topic: Is it possible that I can get chinesse, russian, and some other language (that I don't know, but it sounds like from far south) stations with my old cheap receiver? Receiver is from mid 70s, made in yugoslavia... with fact that yugoslavia was kinda known for low grade electronic devices.
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