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#31
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6L6 substitute
"msg" wrote in message ernet... ken scharf wrote: snip (I've heard of 807's taking over 1000 volts on the plate just fine!). The official ICAS ratings for the 807 allow up to 750 volts at 100ma plate current, and there is a typical operation shown at 75 watts input, so at 50w your transmitter wasn't even breaking a sweat yet! A pair of 807's in AB2 (SSB linear) will put out 120w PEP, just about the same as a pair of 6146's. The 6146B officially will do about 135-140w in the same service. snip FWIW, here is a homebrew quad 837/807 linear that does 2kw PEP with 2KV on the plates (I have it but did not homebrew this one): http://www.cybertheque.org/homebrew/837_linear I took the photos some years ago using a digital camera with focus and image burn issues; this summer I intend to reshoot these with a better camera. Michael Looks good! For "on-line" viewing the photos you took look fine on this end. |
#32
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6L6 substitute
On Sun, 07 Dec 2008 13:08:00 -0600, msg wrote:
ken scharf wrote: snip (I've heard of 807's taking over 1000 volts on the plate just fine!). The official ICAS ratings for the 807 allow up to 750 volts at 100ma plate current, and there is a typical operation shown at 75 watts input, so at 50w your transmitter wasn't even breaking a sweat yet! A pair of 807's in AB2 (SSB linear) will put out 120w PEP, just about the same as a pair of 6146's. The 6146B officially will do about 135-140w in the same service. snip FWIW, here is a homebrew quad 837/807 linear that does 2kw PEP with 2KV on the plates (I have it but did not homebrew this one): http://www.cybertheque.org/homebrew/837_linear I took the photos some years ago using a digital camera with focus and image burn issues; this summer I intend to reshoot these with a better camera. Michael I built a 837 "linear" back around 1958. I used mercury vapor rectifier tubes - love that blue glow. It worked pretty well at about 1200V. I used it mostly for CW and some AM. The 837s were cheap and pretty rugged. Damn near killed my self on the high voltage so I got rid of it. Bruce W0BF |
#33
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6L6 substitute
On Sat, 06 Dec 2008 16:41:00 -0500, ken scharf
wrote: Fred McKenzie wrote: In article , JIMMIE wrote: I am considering an 807 as a replacement Jimmie- Just how simple will this transmitter be? My first novice transmitter was built from an ARRL publication back in the 50s. The specification was for a single 6V6, used as a crystal oscillator with output coupled to the antenna. I found I could get more power with a 6L6 plugged into the same socket. Along the way to getting more power, I found that crystal current would increase to the point where the crystal would fracture! If you use a 807 or 1625, I hope you will have a lower power oscillator driving it. Something like a 6AG7 would make a nice crystal oscillator, and should have sufficient output to drive an 807. 73, Fred K4DII The 6AG7 - 807 combo is a classic. E. F. Johnson sold a 50 Watt Novice transmitter in the '50's with this tube line up (also a 5R4GY rectifier IIRC). Other tubes that have been used as the oscillator/driver were the 6CL6, 12BY7, 6GK6, and 5763. That would be the Johnson Viking Adventurer. I built one in 1955 from a kit. I later replaced the 807 with a 6146 - didn't make much difference, actually. Bruce W0BF |
#34
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6L6 substitute
"Bruce W. Ellis" wrote in message ... On Sat, 06 Dec 2008 16:41:00 -0500, ken scharf wrote: Fred McKenzie wrote: In article , JIMMIE wrote: I am considering an 807 as a replacement Jimmie- Just how simple will this transmitter be? My first novice transmitter was built from an ARRL publication back in the 50s. The specification was for a single 6V6, used as a crystal oscillator with output coupled to the antenna. I found I could get more power with a 6L6 plugged into the same socket. Along the way to getting more power, I found that crystal current would increase to the point where the crystal would fracture! If you use a 807 or 1625, I hope you will have a lower power oscillator driving it. Something like a 6AG7 would make a nice crystal oscillator, and should have sufficient output to drive an 807. 73, Fred K4DII The 6AG7 - 807 combo is a classic. E. F. Johnson sold a 50 Watt Novice transmitter in the '50's with this tube line up (also a 5R4GY rectifier IIRC). Other tubes that have been used as the oscillator/driver were the 6CL6, 12BY7, 6GK6, and 5763. That would be the Johnson Viking Adventurer. I built one in 1955 from a kit. I later replaced the 807 with a 6146 - didn't make much difference, actually. Bruce W0BF Yep, that's what I started out with. Bought my Adventurer used back in 1964 along with an HQ-110c. When I got my General ticket I got a nice drifty Knight Kit VFO. My antenna relay was taken from an old pinball machine! My best contact was Ascension Island . Africa on a 40 meter CW.. I used a wire vertical... that was not terribly vertical G |
#35
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6L6 substitute
On Dec 5, 11:28*am, Tim Wescott wrote:
On Thu, 04 Dec 2008 06:23:48 -0800, JIMMIE wrote: After years of avoiding morse code I am finally getting into it. the ideal of operating a very simple transmitter appeals to my junkbox/ trashcan construction mentality. I am looking for a substitue for a 6L6 that has the plate brought out the top. I was trying to build a little Glowbug transmitter but was having all kinds of problems neutralizing the the thing. I think I would have better luck if I can separate the grid and plate circuits from each other. I am considering an 807 as a replacement Suggestions would be appreciated. Jimmie Have you considered a 6L6 with careful shielding at the socket? *IIRC the pins that neighbor the plate pin would be at RF potential; you could put a big, flat, high-value ceramic right between those socket pins to shield the grid, and possible even extend the shield out if you were willing to hand-make a cap from copper strip and Kapton tape. It's kinda heroic measures to take on a tube that's more expensive now than it's "high-tech" RF brethren, but if you just gotta have that metal- tube look it may do the trick. -- Tim Wescott Control systems and communications consultinghttp://www.wescottdesign.com Need to learn how to apply control theory in your embedded system? "Applied Control Theory for Embedded Systems" by Tim Wescott Elsevier/Newnes,http://www.wescottdesign.com/actfes/actfes.html Thanks Tim, I rplaced the 6L6 with a 6DQ6 and all is right with the world on this end. Im putting out about 40 watts on 80M. My next project may be building a little super rengerative receiver. Im trying to see just how little I can get by with and still have a productive station. Jimmie |
#36
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6L6 substitute
You could try the 5B/254M which is a smaller and slimmer version of the 807.
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#37
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6L6 substitute
"JIMMIE" wrote in message ... .. My next project may be building a little super rengerative receiver. You mean a regenerative receiver, surely? |
#38
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6L6 substitute
On Dec 8, 5:15*am, "Theo" wrote:
"JIMMIE" wrote in message ... . My next project may be building a little super rengerative receiver. You mean a regenerative receiver, surely? Yes one should not type and carry on a conversation with thier wife at the same time. Jimmie |
#39
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6L6 substitute
On Mon, 8 Dec 2008 10:07:11 -0000, "Theo"
wrote: You could try the 5B/254M which is a smaller and slimmer version of the 807. Somewhat OT.. Oldtimers refer to a bottle of beer as an 807. Never heard of a 6L6GT referred to that way. I suppose a whiskey bottle could be called an 813. Time for a couple of 807's. Bruce W0BF |
#40
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6L6 substitute
ken scharf wrote:
Tim Wescott wrote: On Thu, 04 Dec 2008 06:23:48 -0800, JIMMIE wrote: After years of avoiding morse code I am finally getting into it. the ideal of operating a very simple transmitter appeals to my junkbox/ trashcan construction mentality. I am looking for a substitue for a 6L6 that has the plate brought out the top. I was trying to build a little Glowbug transmitter but was having all kinds of problems neutralizing the the thing. I think I would have better luck if I can separate the grid and plate circuits from each other. I am considering an 807 as a replacement Suggestions would be appreciated. Jimmie Dunno if it's been mentioned yet -- 2E26. The 807 is _not_ a 6L6 in a different envelope -- it's quit arguably the 6L6's big brother, but it's got different ratings; it could probably be shoe-horned into a circuit designed for the 6L6, but you'd be missing out on about 6dB of final output power. The 807 IS a 6L6G with a 5 pin base and the plate connected to the top. The published ratings of the 6L6G look different than the 807 because of their intended use. ICAS ratings for the 6L6G were never published. Also the 807 has additional shielding and insulation over the 6L6G that make it usable at higher frequencies and voltages than the 6L6G. Most 807's have ceramic spaces to support the plate which are lacking in the 6L6G. But make no mistake about it, the two tubes share the IDENTICAL cathode, grids, and plate structures. The 6BG6G tv sweep tube IS an 807 with an octal base. It has the same ceramic plate supports, but lacks the extra rf shielding. The 1625 is an 807 with a 12.6 volt heater and a large (same as type '59) 7 pin base. The type 1614 is a metal tube based on the 6L6. It is a transmitting version, and probably has additional shielding. Otherwise its internal structure is the same as the 6L6 metal type. The type 1619 is sorta kinda a 6L6 with a directly heated 2.5v cathode. Same metal bulb as the 6L6. Specs' are different due to the different element spacing thanks to the filament cathode. This tube is often triode connected to replace 45's and 2A3's in old radios with a socket adapter. As a result the of the construction differences regarding shielding, the 807 often would NOT need neutralization while 6L6G's and 6BG6G tubes used as rf power amps do. The 6L6GA was identical to the 6L6G except that the bulb shrunk from an ST16 to an ST14 size. The 6L6GB was identical except for the bulb changing again to a T14. The 6L6GC is a totally different bottle with higher plate and screen dissipation and plate voltage ratings. The 6L6GC was said to be a plug in replacement for the older 6L6 tubes, but RCA kept the 6L6GB around for a while anyway. In fact a bias re-adjustment was a good idea when replacing an older 6L6 with the 'GC version if a cathode bias resistor wasn't used. I bow to your superior knowledge. How do you know? Time spent busting tubes and looking inside? Old-time service and/or circuit design experience? Experience building tubes? I'd love to see a detailed family tree for some of the more popular tube types. -- Tim Wescott Wescott Design Services http://www.wescottdesign.com Do you need to implement control loops in software? "Applied Control Theory for Embedded Systems" gives you just what it says. See details at http://www.wescottdesign.com/actfes/actfes.html |
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