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One tube transmitter
1 Attachment(s)
Capable of 100% modulation and has fairly good fidelity.
-- Kind regards, Terry Judkins |
One tube transmitter
TerryJ wrote:
Capable of 100% modulation and has fairly good fidelity. How do I tell if it uses AM or FM transmission signals? The diagram shows nothing in reference to a FM or AM transmission bands. -- Johnny Byrns (http://www.fmamradios.com/Johnny's.html) |
One tube transmitter
On Thu, 05 Jul 2007 19:00:17 GMT, "Johnny Byrns"
wrote: TerryJ wrote: Capable of 100% modulation and has fairly good fidelity. How do I tell if it uses AM or FM transmission signals? The diagram shows nothing in reference to a FM or AM transmission bands. For one thing, the audio input is fed directly to a transformer in the plate circuit of the oscillator tube. Classic AM. Next, the oscillator is fixed at 1 MHz by the crystal. No audio gets into the oscillator grid or cathode to FM it. ============== Dave M Never take a laxative and a sleeping pill at the same time!! |
One tube transmitter
In message , Dave M
writes On Thu, 05 Jul 2007 19:00:17 GMT, "Johnny Byrns" wrote: TerryJ wrote: Capable of 100% modulation and has fairly good fidelity. How do I tell if it uses AM or FM transmission signals? The diagram shows nothing in reference to a FM or AM transmission bands. For one thing, the audio input is fed directly to a transformer in the plate circuit of the oscillator tube. Classic AM. Next, the oscillator is fixed at 1 MHz by the crystal. No audio gets into the oscillator grid or cathode to FM it. ============== Dave M Never take a laxative and a sleeping pill at the same time!! You would find it rather difficult to FM a crystal oscillator. Possible, but difficult. Ian. -- |
One tube transmitter
"Ian Jackson" wrote in message ... In message , Dave M writes On Thu, 05 Jul 2007 19:00:17 GMT, "Johnny Byrns" wrote: TerryJ wrote: Capable of 100% modulation and has fairly good fidelity. How do I tell if it uses AM or FM transmission signals? The diagram shows nothing in reference to a FM or AM transmission bands. For one thing, the audio input is fed directly to a transformer in the plate circuit of the oscillator tube. Classic AM. Next, the oscillator is fixed at 1 MHz by the crystal. No audio gets into the oscillator grid or cathode to FM it. ============== Dave M Never take a laxative and a sleeping pill at the same time!! You would find it rather difficult to FM a crystal oscillator. Possible, but difficult. Ian. -- Many early FM transmitters directly modulated the crystal. This gave only very limited frequency excursion. Full deviation was acheived by frequency multiplication. Long since, simpler methods have been used such as heterodyning of a second, AFC controlled oscillator and of course the currently common PLL systems. |
One tube transmitter
In article ,
Ian Jackson wrote: In message , Dave M writes On Thu, 05 Jul 2007 19:00:17 GMT, "Johnny Byrns" wrote: TerryJ wrote: Capable of 100% modulation and has fairly good fidelity. How do I tell if it uses AM or FM transmission signals? The diagram shows nothing in reference to a FM or AM transmission bands. For one thing, the audio input is fed directly to a transformer in the plate circuit of the oscillator tube. Classic AM. Next, the oscillator is fixed at 1 MHz by the crystal. No audio gets into the oscillator grid or cathode to FM it. ============== Dave M Never take a laxative and a sleeping pill at the same time!! You would find it rather difficult to FM a crystal oscillator. Possible, but difficult. Ian. Some of the early BBC FM transmitters did exactly that, FM a crystal oscillator. Regards, John Byrns -- Surf my web pages at, http://fmamradios.com/ |
One tube transmitter
In article ,
"Brenda Ann" wrote: "Ian Jackson" wrote in message ... In message , Dave M writes On Thu, 05 Jul 2007 19:00:17 GMT, "Johnny Byrns" wrote: TerryJ wrote: Capable of 100% modulation and has fairly good fidelity. How do I tell if it uses AM or FM transmission signals? The diagram shows nothing in reference to a FM or AM transmission bands. For one thing, the audio input is fed directly to a transformer in the plate circuit of the oscillator tube. Classic AM. Next, the oscillator is fixed at 1 MHz by the crystal. No audio gets into the oscillator grid or cathode to FM it. ============== Dave M Never take a laxative and a sleeping pill at the same time!! You would find it rather difficult to FM a crystal oscillator. Possible, but difficult. Ian. -- Many early FM transmitters directly modulated the crystal. This gave only very limited frequency excursion. Full deviation was acheived by frequency multiplication. Long since, simpler methods have been used such as heterodyning of a second, AFC controlled oscillator and of course the currently common PLL systems. Most early FM transmitters used frequency multiplication irrespective of how they were modulated. In the US prior to the introduction of stereo phase modulation was the predominant method of doing FM and required a very high amount of frequency multiplication to achieve 100% FM modulation at low audio frequencies. Even PLL type modulators like the RCA system ran the modulated VCO at somewhere around 5 MHz and used frequency multiplication to get up into the FM band. Regards, John Byrns -- Surf my web pages at, http://fmamradios.com/ |
One tube transmitter
You would find it rather difficult to FM a crystal oscillator.
Possible, but difficult. Not really. It's done all the time in temperature-compensated oscillators, simply by varying the series or load capacitance. |
FM One tube transmitter
Excuse me, but that circuit uses two tubes.
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FM One tube transmitter
Shouldn't diodes count as "tubes", if only in an "antique" sense?
"William Sommerwerck" wrote in message . .. Excuse me, but that circuit uses two tubes. |
One tube transmitter
In message , William
Sommerwerck writes You would find it rather difficult to FM a crystal oscillator. Possible, but difficult. Not really. It's done all the time in temperature-compensated oscillators, simply by varying the series or load capacitance. OK then - 'Possible, but much more difficult than with a free-running L-C circuit'. When an oscillator is crystal controlled, to get a lot of FM, it usually takes a bit more than 'slipping a variap' into the circuit. You usually have to use some form of VXO circuit. Even then, the amount of FM you get can depend a lot on the characteristics of the crystal. And it may not be very linear. But it all depends on what you need. Some early crystal-controlled FM equipment avoids the problems of FMing the crystal itself. Instead, in a later stage they phase-modulate the signal (producing a predictable amount of PM) and, of course, multiply up to the final frequency. Ian. -- |
FM One tube transmitter
No mention of "antique" at all, just "one tube", and when I look at
a 6J6 I see one tube... :) unless I have had a few too many then? If someone said "design such-and-such using a single tube", would it be fair to use a Compactron? When you describe a circuit as being "single-tube", the implication is that the tube is not a multi-section device. |
FM One tube transmitter
In article ,
"William Sommerwerck" wrote: No mention of "antique" at all, just "one tube", and when I look at a 6J6 I see one tube... :) unless I have had a few too many then? If someone said "design such-and-such using a single tube", would it be fair to use a Compactron? Yes, a tube is a tube is a tube. When you describe a circuit as being "single-tube", the implication is that the tube is not a multi-section device. No, you have to be specific if you mean a single section tube. Regards, John Byrns -- Surf my web pages at, http://fmamradios.com/ |
FM One tube transmitter
No ,
It uses a single 2 section tube tube Pronunciation: \'tüb, 'tyüb\ Function:noun Etymology:French, from Latin tubus; akin to Latin tuba trumpet Date:1651 a hollow elongated cylinder; electron tube Main Entry:electron tube Function:noun Date:1922 an electronic device in which conduction by electrons takes place through a vacuum or a gaseous medium within a sealed glass or metal container and which has various uses based on the controlled flow of electrons -- Carl WA1KPD Visit My Boatanchor Collection at http://home.comcast.net/~chnord/wa1kpd.html "William Sommerwerck" wrote in message . .. Excuse me, but that circuit uses two tubes. |
FM One tube transmitter
Terry,
I'll bet your sorry you ever shared this! -- Carl WA1KPD Visit My Boatanchor Collection at http://home.comcast.net/~chnord/wa1kpd.html "TerryJ" suptjudatcomcastdotnet wrote in message ... FM with one tube..... "TerryJ" suptjudatcomcastdotnet wrote in message ... Note the one MHz crystal oscillator? AM..... "Johnny Byrns" wrote in message ... TerryJ wrote: Capable of 100% modulation and has fairly good fidelity. How do I tell if it uses AM or FM transmission signals? The diagram shows nothing in reference to a FM or AM transmission bands. -- Johnny Byrns (http://www.fmamradios.com/Johnny's.html) |
FM One tube transmitter
Carl WA1KPD wrote:
Terry, I'll bet your sorry you ever shared this! ------------------------------------------------- Terry - Despite the rather senseless carping (c'mon boys, cut the crap!), this is cool! Thanks for posting it! Bill |
FM One tube transmitter
Carl WA1KPD wrote:
No , It uses a single 2 section tube tube Pronunciation: \?tüb, ?tyüb\ Function:noun Etymology:French, from Latin tubus; akin to Latin tuba trumpet Date:1651 a hollow elongated cylinder; electron tube Main Entry:electron tube Function:noun Date:1922 an electronic device in which conduction by electrons takes place through a vacuum or a gaseous medium within a sealed glass or metal container and which has various uses based on the controlled flow of electrons Please don't use HTML The text in your message is just streaks across the monitor. -- Service to my country? Been there, Done that, and I've got my DD214 to prove it. Member of DAV #85. Michael A. Terrell Central Florida |
FM One tube transmitter
Carl WA1KPD wrote:
Terry, I'll bet your sorry you ever shared this! That's like an auction I'm running now, for a (pair of 7591's). I have gotten four questions on how many tubes there are, one tube, two pair etc etc. Think shoes.Ken |
FM One tube transmitter
Nicely done. I like the dual varactor arrangement, which should have
a lot of advantages over a single diode. All in all, simple and elegant! Pete |
FM One tube transmitter
Despite the rather senseless carping (c'mon boys, cut the crap!), this is
cool! Thanks for posting it! I agree. An interesting post. And now for my usual dumb questions :-) 1. Have you built one (or more) and if so, could we see a photo? 2. What do you mean by "star grounding technique?" Phil Nelson |
FM One tube transmitter
"Phil Nelson" wrote in message ... Despite the rather senseless carping (c'mon boys, cut the crap!), this is cool! Thanks for posting it! I agree. An interesting post. And now for my usual dumb questions :-) 1. Have you built one (or more) and if so, could we see a photo? 2. What do you mean by "star grounding technique?" Phil Nelson Star grounding is a VHF/UHF grounding technique. VHF and higher have to have VERY short lead dress, including grounding. Star grounding is basically taking the grounds from each pin that requires a ground or a bypass to the closest point possible on the chassis. This makes the socket and grounds/bypasses resemble a star. |
FM One tube transmitter
Uncle Peter wrote:
Nicely done. I like the dual varactor arrangement, which should have a lot of advantages over a single diode. All in all, simple and elegant! Pete If I'm reading correctly, the "varactor" is a pair of plain old rectifier diodes! I never would have thought of using power diodes for this application. I guess I thought there would have been way too much capacitance to be able to reasonably resonate them at 100 MHz. Good stuff! Bill |
FM One tube transmitter
If I'm reading correctly, the "varactor" is a pair of plain old
rectifier diodes! I never would have thought of using power diodes for this application. I guess I thought there would have been way too much capacitance to be able to reasonably resonate them at 100 MHz. Good stuff! About 45 years ago, Popular Electronics had a construction project for an FM-band transmitter. It used a reverse-biased silicon rectifier to modulate the carrier. I assume two back-to-back diodes increases the linearity of the modulation. |
FM One tube transmitter
"Brian McAllister" wrote in message ... On Sun, 8 Jul 2007 16:18:15 +0900, "Brenda Ann" wrote: "Phil Nelson" wrote in message om... Despite the rather senseless carping (c'mon boys, cut the crap!), this is cool! Thanks for posting it! I agree. An interesting post. And now for my usual dumb questions :-) 1. Have you built one (or more) and if so, could we see a photo? 2. What do you mean by "star grounding technique?" Phil Nelson Star grounding is a VHF/UHF grounding technique. VHF and higher have to have VERY short lead dress, including grounding. Star grounding is basically taking the grounds from each pin that requires a ground or a bypass to the closest point possible on the chassis. This makes the socket and grounds/bypasses resemble a star. At the audio manufacturer where I worked, star grounding meant to take all grounds to a single point on the chassis, thus having ground wires radiate like the points on a star. This avoided ground currents flowing through the chassis. Brian McAllister That's interesting, and makes sense for audio certainly, but would not be feasible at 100 MHz, as it would create lead lengths that would be a significant inductance at that frequency. |
FM One tube transmitter
Brian is using the term correctly, but Star grounds are not used in RF
equipment. See link below. The shortest path to ground should be used. http://www.maxim-ic.com/glossary/ind...Tm/Star_Ground -- Tom Mills "Brian McAllister" wrote in message ... On Sun, 8 Jul 2007 16:18:15 +0900, "Brenda Ann" wrote: "Phil Nelson" wrote in message om... Despite the rather senseless carping (c'mon boys, cut the crap!), this is cool! Thanks for posting it! I agree. An interesting post. And now for my usual dumb questions :-) 1. Have you built one (or more) and if so, could we see a photo? 2. What do you mean by "star grounding technique?" Phil Nelson Star grounding is a VHF/UHF grounding technique. VHF and higher have to have VERY short lead dress, including grounding. Star grounding is basically taking the grounds from each pin that requires a ground or a bypass to the closest point possible on the chassis. This makes the socket and grounds/bypasses resemble a star. At the audio manufacturer where I worked, star grounding meant to take all grounds to a single point on the chassis, thus having ground wires radiate like the points on a star. This avoided ground currents flowing through the chassis. Brian McAllister Sarasota, Florida email bkm at oldtech dot net |
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