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#1
June 5th 05, 05:07 AM
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2C39's for 144 MHZ?
Hello, Has anyone tried using 2C39's for 144 Mhz? I happen to have a few
of them and was considering using them for a junkbox amplifier for 2 meter SSB. I have found several 1296 Mhz amps that use them, but so far, nothing for 2 meters. Thanks. Russ |
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#2
June 5th 05, 02:37 PM
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On Sun, 05 Jun 2005 04:07:47 GMT, "998 cc"
wrote: Hello, Has anyone tried using 2C39's for 144 Mhz? I happen to have a few of them and was considering using them for a junkbox amplifier for 2 meter SSB. I have found several 1296 Mhz amps that use them, but so far, nothing for 2 meters. Certainly they will work but I suggest the effort will be more trouble than it's worth. |
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#3
June 5th 05, 05:39 PM
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Yes, I should suspect that a lower freq for a high freq tube is no
problem... I think why you don't see them ever used at 144 Mhz is that there used to be VERY expensive--you would only pay the money if necessary and there were much cheaper alternatives for 144... Warmest regards, John "998 cc" wrote in message ... Hello, Has anyone tried using 2C39's for 144 Mhz? I happen to have a few of them and was considering using them for a junkbox amplifier for 2 meter SSB. I have found several 1296 Mhz amps that use them, but so far, nothing for 2 meters. Thanks. Russ |
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#4
June 6th 05, 01:13 AM
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From: "John Smith" on Sun,Jun 5 2005 12:39
pm Yes, I should suspect that a lower freq for a high freq tube is no problem... I think why you don't see them ever used at 144 Mhz is that there used to be VERY expensive--you would only pay the money if necessary and there were much cheaper alternatives for 144... The 2C39 was never intended for lower-frequency "CW" or other narrow-band modes. General Electric used them in 1800 MHz pulsed microwave radio relay terminals having peak pulse envelope output of 12 Watts...with forced-air cooling on the integral anode fins. There were six 2C39s in every GE 1.8 GHz terminal designed about 1950 (!). The transconductance is very high (14,000 umho?) and the grid-cathode, grid-plate spacing very small. The only sure way to hold such tolerances in varying heat environments is to use non-standard glass or ceramic tubing sections in the inverted lighthouse structure. Those who want to use it have to have an equally-expensive socket arrangement or be a fairly competent machinist have good tools at their disposal. The GE microwave terminal used integral socket and tuned cavity assemblies at 1.8 GHz. The GE transmitter was a chain of 7-pin and 9-pin tube oscillator-multipliers to about 255 MHz, then into a 2C39 septupler, that into the 2C39 final amplifier (pulsed anode). Receiver LO had a similar arrangement but only one 2C39 in the chain. "Hot spare" duplicate assemblies for the RF doubled the 2C39 totals. They worked and worked and worked in 24/7 operation, nine terminals where I was the operation and maintenance supervising NCO in the Army. There were hundreds of them used in many kinds of multi-channel radio relay, including long pipeline telemetry and control in the USA. The only thing "bad" about them was due to another tube manuafacturer's dimensional conflict with GE cavity design. Why that particular tube? Because it "looks sexy" with the anode fins so nicely machined? There's lots more half-century-old vacuum tube designs available somewhere. Western Electric 416s and 417s are out there in larger quantities. Geez, 829 duals have been used at 144 MHz with more output than one can safely run a 2C39 at that frequency. Socket assemblies for an 829 are easier to get than for an inverted lighthouse structure. A year or so ago I happened across a couple of non-USA sites giving nice details of 2C39s used in ham VHF transmitters. Nice photos and dimensions available. Both of them used the triode "pushed" beyond its safe limits of power. Think about replacement costs. At 2 meters, a better way using vacuum tubes (besides going to Eimac goodies) is in a "distributed amplifier," the grids of many 9-pin tubes connected to an L-C delay-line-like structure, the plates connected to another L-C network. The Tektronix 540 series scopes had those for the vertical amplifiers, good beyond 50 MHz, back in the 1960s. No tuning required...except in how to couple the medium-Z output to a low-Z antenna. Or...one can get transistors that have worked in their ratings at 150 MHz VHF "business band" with all the nitty and gritty details in old Motorola Application Notes. CW operation at 2 meters no sweat at up to 150 Watts, more than a 2C39 pair can do safely. Lots of alternate choices...such as solid-state Cellular Telephone cell site ("base station") transmitters and equivalents that don't have internal networks to optimize operation in the 1 GHz band. [but, you knew that already, right? :-) ] |
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#5
June 6th 05, 01:40 AM
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yes, you will forgive me if I skip reading all of that, I doubt you
offered anything relevant to the mans original question anyway... John wrote in message oups.com... From: "John Smith" on Sun,Jun 5 2005 12:39 pm Yes, I should suspect that a lower freq for a high freq tube is no problem... I think why you don't see them ever used at 144 Mhz is that there used to be VERY expensive--you would only pay the money if necessary and there were much cheaper alternatives for 144... The 2C39 was never intended for lower-frequency "CW" or other narrow-band modes. General Electric used them in 1800 MHz pulsed microwave radio relay terminals having peak pulse envelope output of 12 Watts...with forced-air cooling on the integral anode fins. There were six 2C39s in every GE 1.8 GHz terminal designed about 1950 (!). The transconductance is very high (14,000 umho?) and the grid-cathode, grid-plate spacing very small. The only sure way to hold such tolerances in varying heat environments is to use non-standard glass or ceramic tubing sections in the inverted lighthouse structure. Those who want to use it have to have an equally-expensive socket arrangement or be a fairly competent machinist have good tools at their disposal. The GE microwave terminal used integral socket and tuned cavity assemblies at 1.8 GHz. The GE transmitter was a chain of 7-pin and 9-pin tube oscillator-multipliers to about 255 MHz, then into a 2C39 septupler, that into the 2C39 final amplifier (pulsed anode). Receiver LO had a similar arrangement but only one 2C39 in the chain. "Hot spare" duplicate assemblies for the RF doubled the 2C39 totals. They worked and worked and worked in 24/7 operation, nine terminals where I was the operation and maintenance supervising NCO in the Army. There were hundreds of them used in many kinds of multi-channel radio relay, including long pipeline telemetry and control in the USA. The only thing "bad" about them was due to another tube manuafacturer's dimensional conflict with GE cavity design. Why that particular tube? Because it "looks sexy" with the anode fins so nicely machined? There's lots more half-century-old vacuum tube designs available somewhere. Western Electric 416s and 417s are out there in larger quantities. Geez, 829 duals have been used at 144 MHz with more output than one can safely run a 2C39 at that frequency. Socket assemblies for an 829 are easier to get than for an inverted lighthouse structure. A year or so ago I happened across a couple of non-USA sites giving nice details of 2C39s used in ham VHF transmitters. Nice photos and dimensions available. Both of them used the triode "pushed" beyond its safe limits of power. Think about replacement costs. At 2 meters, a better way using vacuum tubes (besides going to Eimac goodies) is in a "distributed amplifier," the grids of many 9-pin tubes connected to an L-C delay-line-like structure, the plates connected to another L-C network. The Tektronix 540 series scopes had those for the vertical amplifiers, good beyond 50 MHz, back in the 1960s. No tuning required...except in how to couple the medium-Z output to a low-Z antenna. Or...one can get transistors that have worked in their ratings at 150 MHz VHF "business band" with all the nitty and gritty details in old Motorola Application Notes. CW operation at 2 meters no sweat at up to 150 Watts, more than a 2C39 pair can do safely. Lots of alternate choices...such as solid-state Cellular Telephone cell site ("base station") transmitters and equivalents that don't have internal networks to optimize operation in the 1 GHz band. [but, you knew that already, right? :-) ] |
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#6
June 6th 05, 05:31 PM
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"John Smith" wrote in message ... yes, you will forgive me if I skip reading all of that, I doubt you offered anything relevant to the mans original question anyway... Yeah, don't confuse us with theory and engineering- especially stay away from any math. But to Len, Thanks for the informative post. I have used 2C39's on 23cM in 2 and 4 tube water cooled designs for EME, but appreciate your insight into the construction and caveats. Dale W4OP |
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#7
June 6th 05, 06:27 PM
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the guy asking about using 'em on 144 Mhz will be thrilled by the
reports of another Ghz user... John "Dale Parfitt" wrote in message news:fT_oe.2741$Kj3.761@trnddc03... "John Smith" wrote in message ... yes, you will forgive me if I skip reading all of that, I doubt you offered anything relevant to the mans original question anyway... Yeah, don't confuse us with theory and engineering- especially stay away from any math. But to Len, Thanks for the informative post. I have used 2C39's on 23cM in 2 and 4 tube water cooled designs for EME, but appreciate your insight into the construction and caveats. Dale W4OP |
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#9
June 7th 05, 10:44 PM
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On Sun, 05 Jun 2005 06:37:02 -0700, Wes Stewart
wrote: On Sun, 05 Jun 2005 04:07:47 GMT, "998 cc" wrote: Hello, Has anyone tried using 2C39's for 144 Mhz? I happen to have a few of them and was considering using them for a junkbox amplifier for 2 meter SSB. I have found several 1296 Mhz amps that use them, but so far, nothing for 2 meters. Certainly they will work but I suggest the effort will be more trouble than it's worth. I've used them aircooled at 432 but thy are only good for maybe 15W that way. A pair running grounded grid at 144 would work but for the it's a lot of work unless you go to the trouble of water cooling. I'd use 4CX250 before I'd bother with that. FYI the motorola H44s (a old tube UHF FM business radio used 2C39s for the driver and final). Allison |
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#10
June 8th 05, 05:05 AM
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Hello Len and All. Thanks for the replies. I found all of the "positive"
responses very beneficial including the Ghz responses. The reason for my enquiry is that I have some of these tubes and related surplus equipment and was looking for a way to use the parts from it. In fact, I believe the equipment I have is one of the pulsed relay stations mentioned below. I have one complete Lo-band unit except for the horn antenna. It sounds like the end would not justify the means in considering these tubes as viable 2-meter amps. I do have a few 829/3E29's and sockets in the parts box, so that is a possibility as well. Anyway, I like tube equipment which is why I am not going the solid state route. Thanks again. 73, Russ W6OHM wrote in message oups.com... From: "John Smith" on Sun,Jun 5 2005 12:39 pm Yes, I should suspect that a lower freq for a high freq tube is no problem... I think why you don't see them ever used at 144 Mhz is that there used to be VERY expensive--you would only pay the money if necessary and there were much cheaper alternatives for 144... The 2C39 was never intended for lower-frequency "CW" or other narrow-band modes. General Electric used them in 1800 MHz pulsed microwave radio relay terminals having peak pulse envelope output of 12 Watts...with forced-air cooling on the integral anode fins. There were six 2C39s in every GE 1.8 GHz terminal designed about 1950 (!). The transconductance is very high (14,000 umho?) and the grid-cathode, grid-plate spacing very small. The only sure way to hold such tolerances in varying heat environments is to use non-standard glass or ceramic tubing sections in the inverted lighthouse structure. Those who want to use it have to have an equally-expensive socket arrangement or be a fairly competent machinist have good tools at their disposal. The GE microwave terminal used integral socket and tuned cavity assemblies at 1.8 GHz. The GE transmitter was a chain of 7-pin and 9-pin tube oscillator-multipliers to about 255 MHz, then into a 2C39 septupler, that into the 2C39 final amplifier (pulsed anode). Receiver LO had a similar arrangement but only one 2C39 in the chain. "Hot spare" duplicate assemblies for the RF doubled the 2C39 totals. They worked and worked and worked in 24/7 operation, nine terminals where I was the operation and maintenance supervising NCO in the Army. There were hundreds of them used in many kinds of multi-channel radio relay, including long pipeline telemetry and control in the USA. The only thing "bad" about them was due to another tube manuafacturer's dimensional conflict with GE cavity design. Why that particular tube? Because it "looks sexy" with the anode fins so nicely machined? There's lots more half-century-old vacuum tube designs available somewhere. Western Electric 416s and 417s are out there in larger quantities. Geez, 829 duals have been used at 144 MHz with more output than one can safely run a 2C39 at that frequency. Socket assemblies for an 829 are easier to get than for an inverted lighthouse structure. A year or so ago I happened across a couple of non-USA sites giving nice details of 2C39s used in ham VHF transmitters. Nice photos and dimensions available. Both of them used the triode "pushed" beyond its safe limits of power. Think about replacement costs. At 2 meters, a better way using vacuum tubes (besides going to Eimac goodies) is in a "distributed amplifier," the grids of many 9-pin tubes connected to an L-C delay-line-like structure, the plates connected to another L-C network. The Tektronix 540 series scopes had those for the vertical amplifiers, good beyond 50 MHz, back in the 1960s. No tuning required...except in how to couple the medium-Z output to a low-Z antenna. Or...one can get transistors that have worked in their ratings at 150 MHz VHF "business band" with all the nitty and gritty details in old Motorola Application Notes. CW operation at 2 meters no sweat at up to 150 Watts, more than a 2C39 pair can do safely. Lots of alternate choices...such as solid-state Cellular Telephone cell site ("base station") transmitters and equivalents that don't have internal networks to optimize operation in the 1 GHz band. [but, you knew that already, right? :-) ] |
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