Valve based Crystal Oscillator.

   Does anyone know where I can find a circuit to build a modulated 100kHz oscillator using a b7g based crystal and a triode valve?  I've searched the internet for weeks without success!  I'd be glad of any leads you can give.

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Mike Members Profile Send Private Message Find Members Posts Add to Buddy List Guest	Post Options Post Reply Quote Mike Quote Reply Topic: Valve based Crystal Oscillator. Posted: 09-Jun-10 at 19:17
	Does anyone know where I can find a circuit to build a modulated 100kHz oscillator using a b7g based crystal and a triode valve? I've searched the internet for weeks without success! I'd be glad of any leads you can give.

Ivan Members Profile Send Private Message Find Members Posts Add to Buddy List Moderator Group Joined: 08-Aug-21 Location: Praha Online Status: Offline Posts: 398	Post Options Post Reply Quote Ivan Report Post Quote Reply Posted: 09-Jun-11 at 08:18
	Hi Mike, what type of modulation do you have in mind ? FM and PM are hard to accomplish with crystals - the crystal is used to avoid variations of frequency / phase. AM is better to get in a separate modulator: if you use a common dual triode, one section will work as an oscillator, the other will be modulated into the grid or anode. BR from Ivan OK1SIP

mikeinbeverley Members Profile Send Private Message Find Members Posts Add to Buddy List Newbie Joined: 09-Jun-11 Location: UK Online Status: Offline Posts: 2	Post Options Post Reply Quote mikeinbeverley Report Post Quote Reply Posted: 09-Jun-11 at 21:28
	Hello, there! Thanks for replying. What I had in mind is a simple 100kHz oscillator based on an ECC81 & a B7G based crystal, as you suggest, Amplitude Modulated. The oscillator circuit I'm using works fine at 1 mHz & above, but I'm having problems making it work at 100kHz. Similarly, I have made a valve audio oscillator work, in the same ECC81, & tried capacitor linking it to the hf side, but without success. A transistor version I built uses a miniature transformer to modulate the oscillator power supply, & is a great success (although it also will not work down as low as 100kHz!!) I don't think I need to resort to a transformer for the valve version. I used to build radios as a hobby in the 1960's, but never got round to building a valve based frequency marker, so I'd like to satisfy my curiosity by building one now! What I really need is a circuit diagram from "the old days" but so far I'e been unable to locate one. - Mike.
	I'm an Analogue Person in a Digital World!

DL9FF Members Profile Send Private Message Find Members Posts Add to Buddy List Newbie Joined: 09-Sep-12 Location: Germany Online Status: Offline Posts: 2	Post Options Post Reply Quote DL9FF Report Post Quote Reply Posted: 09-Sep-12 at 17:16
	Hy, if You want a frequency marker with highest accuracy use droitwich on 200kc. I have 1 unit where the layout is from the early 50,s goto: jogis-roehrenbude.de/Sender/KW-Sender.html its a scan from a drawing first published in DL-QTC 11/1954 it works fine. Only problem is to make a coil for receiving the frequency tzo get Droitwich at 200kc. The unit receives the signal, amplifies it and delivers it to a flip-flop with ECC82 or simmilar. I used a Yankee 6SN7 out of my junk-box (the tube) That flip-flop generates a marker every 100kc up to the VHF-Range. Valve based Quarz-Oszillartors are found at: the Radio Amateurs handbook Edition 1970 or earlier. Good Luck Fritz

mikeinbeverley Members Profile Send Private Message Find Members Posts Add to Buddy List Newbie Joined: 09-Jun-11 Location: UK Online Status: Offline Posts: 2	Post Options Post Reply Quote mikeinbeverley Report Post Quote Reply Posted: 09-Sep-28 at 22:13
	Hi, Fritz! Thanks for that - I'll add it to my list of Winter projects! I have a sweep-frequency generator to finish first. All good fun! Mike. (G4CQN).