The 36KD6 heater draws 450 mA. Four of them is comfortably below 2 Amps.
73
73
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Contex 500 Tube Amp
- Thread starter Shadetree Mechanic
- Start date
STM,
Here is a datasheet I have found for the 40KG6A/PL519.
http://frank.yueksel.org/sheets/010/p/PL519.pdf
300mA @ 40V on the heaters/filaments
The transformer link from RF parts you posted has an output of 36Vac. The 300mA draw may rise with that lower voltage on the heaters to more than the rated 2a output of the transformer.
Someone smarter than me should be able to confirm or dismiss that notion. Just food for thought.
73's
David
Here is a datasheet I have found for the 40KG6A/PL519.
http://frank.yueksel.org/sheets/010/p/PL519.pdf
300mA @ 40V on the heaters/filaments
The transformer link from RF parts you posted has an output of 36Vac. The 300mA draw may rise with that lower voltage on the heaters to more than the rated 2a output of the transformer.
Someone smarter than me should be able to confirm or dismiss that notion. Just food for thought.
73's
David
If you're willing to replace the tube sockets, this opens up a whole range of other possibilities.
Might as well include some fixed control-grid bias if you're going to rip out the tube sockets.
73
Might as well include some fixed control-grid bias if you're going to rip out the tube sockets.
73
STM,
Since you already have them, I would try the 6KM6's first. You may not get quite the output of the 6LQ6's but it probably would not be noticed on the receiving end.
(Fixed control grid bias-
)
73's
David
Since you already have them, I would try the 6KM6's first. You may not get quite the output of the 6LQ6's but it probably would not be noticed on the receiving end.
(Fixed control grid bias-
)73's
David
The pins on the european tubes are fatter. They will "waller" out the spring contacts inside the tube sockets, unless you change them to match the EL509 or PL519 type tubes. The base of those tubes is called "magnoval", and has the pins on the same diameter circle. but the pins are thicker.
That was what I meant about changing sockets.
Best bang for the buck usually starts with a tube that's compatible with the sockets already in the amplifier. Changing them is a PITA.
73
That was what I meant about changing sockets.
Best bang for the buck usually starts with a tube that's compatible with the sockets already in the amplifier. Changing them is a PITA.
73
6P45S Sweep Tube - $17, Socket - $2. (Russian EL-509's/heavy Glass Mil-spec)
Similar to PL519 except the heater voltage is 6.3V. SK509 type Socket - $2
6P45S -C- Svetlana (aka. EL509 / EL519 ) (6KG6)
https://www.facebook.com/alex.gavva
ur4ll@gmx.com
Chris: Is correct. These tend to spread the 6LQ6/6MJ6 sockets types but do fit. When the tubes got to close too top of cage, I would fasten a small piece of Mica or thin piece of Lexan to top as insulator above them. These are good tubes and vs, changing wiring for others (like the 30-40 volt tubes) IMHO much better choice.
Dr. Alex is a good guy! I have dealt with him on several purchases.
Takes couple, 3 weeks to receive them but ALWAYS arrived in perfect condition from Russia.
All the Best
Gary
PS: At his price you can possibly order spares also, as he will normally combine shipping.
Make sure you spec NOS as there are Zillion's of "Pulls" out there for sale (which are still good)
The Military would run them for "X" hours and pull them regardless of working or not.
https://tubes-store.com/product_info.php?products_id=812&osCsid=4v4dn34oenvsdog2q42m6iavm4
https://tubes-store.com/product_info.php?products_id=24&osCsid=4v4dn34oenvsdog2q42m6iavm4
http://rutubes.com/product/6p45s-el509-6kg6-tube/
Similar to PL519 except the heater voltage is 6.3V. SK509 type Socket - $2
6P45S -C- Svetlana (aka. EL509 / EL519 ) (6KG6)
https://www.facebook.com/alex.gavva
ur4ll@gmx.com
Chris: Is correct. These tend to spread the 6LQ6/6MJ6 sockets types but do fit. When the tubes got to close too top of cage, I would fasten a small piece of Mica or thin piece of Lexan to top as insulator above them. These are good tubes and vs, changing wiring for others (like the 30-40 volt tubes) IMHO much better choice.
Dr. Alex is a good guy! I have dealt with him on several purchases.
Takes couple, 3 weeks to receive them but ALWAYS arrived in perfect condition from Russia.
All the Best
Gary
PS: At his price you can possibly order spares also, as he will normally combine shipping.
Make sure you spec NOS as there are Zillion's of "Pulls" out there for sale (which are still good)
The Military would run them for "X" hours and pull them regardless of working or not.
https://tubes-store.com/product_info.php?products_id=812&osCsid=4v4dn34oenvsdog2q42m6iavm4
https://tubes-store.com/product_info.php?products_id=24&osCsid=4v4dn34oenvsdog2q42m6iavm4
http://rutubes.com/product/6p45s-el509-6kg6-tube/
Wow Chris! What an excellent looking job. Nice and clean. That Vector, and 500 watts (contex,) along with either the 2340 or Madison would give you a great shot at reaching the stations you hear.
What's been your furthest dx contact? Any dx out of the Continental US? I haven't been on th5 air for several months and don't know if there's been skip to other countries. How's my old friend the sonar 2340 treating you? I hate to sound greedy considering I still have the other 2340, but God only knows I wish I didn't part with that one. With that being said I couldn't have imagined it going to a better home. It's strange how we get attached to inanimate objects. That 2340 was part of my collection for sooooo long. I think you mentioned running some sort or outboard audio gear. If that's the case please exspand on what you did. If you could add a few photos of the sonar with the audio gear hooked up I'd appreciate it. 73 PS. Things are getting better for me and although I've said it before I think we're going to get together soon in order to hand off those items I have for you. That will include the lmr400 (so you could add the new connectors. I also want to give you that 5 pin interface so you could convert it over to the 1/4" phone plug for my 2340. I have a Beringer 802, and Shure sm58. I have nothing to loose giving the Sonar an outboard 3 band eq/mixer. Those items are just sitting in the closet doing nothing. I recall Mike telling me the 2340 operates at 3khz wide. If that's the case the 802, and sm58 might give the Sonar's audio some more depth as far as adding a bit of bass to it goes.
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Thanks Jojo, I just hooked it up and the power is up to almost 400w with the shorter tubes. Talked to a guy about 15 miles away that said it sounds great. That 2340 is really a jem. When the DX is running, I can normally talk to everyone on this side of the Mississippi River at least. On rare occasion I have talked to California.
I'm assuming DX across the Atlantic isn't currently running. It's been so long and I haven't been looking at the YouTube DX clips. What were the original tubes and what did you replace them with? 400-500 watts is imo a sort of benchmark. Considering one would have to run 2KW in order to gain a single s unit, 400-500 is always a safe bet when deciding on an amp and it's output. It's the reason I would drive the Phantom so that I would get 500 instead of the 800+ it would get when driving it with 3 watts as oppeses to the 1 1/2 I drove it with, and will continue to drive it with when I get back on the air. Why push it to the max when there's a negligible difference between the 500 and the almost 900 that it will do. I am sure that driving it the way I have, and will continue to is the reason why it's 6LQ6's are original. I know the day may come when I have to change out those d&a stamped Sylvanias.
It may sound silly, but there's something about having those d&a tube still in the amp, and giving close too full output if not full output. I once drove it with 4 DK, and 20 pep (on AM) and saw a kw+. There's a beautiful Maverick currently available on eBay. I think it's advertised as working 100%, but has it's original caps. I wouldn't consider it pristine but for its age it is in wonderful cosmetic condition. I am trying my best not to make an offer, but I'm finding it difficult. It would look terrific next to the Phantom. I don't know if you're in the market for another amplifier Chris, but taking into consideration you are obviously up for doing the recap I would take a look at that Maverick (if I were you.) That's if you're in the market for another amplifier. Ones in that cosmetic condition don't come along too often. cosmetics is the first hint as to how the amplifier has been treated throughout its lifetime, and this one has definitely been treated with gloves. The shipping cost is some what out of control, but since it's a best offer auction gives a potential buyer some leverage. I would offer $225 for the amplifier, and see what happens. Even if you can get it for $250 + the $100+ shipping imo $360 (with shipping) is worth it. I've been looking at Mavericks on eBay 4 about 5 years, and I'm almost positive this is the cleanest one I've ever seen. It truly is a beautiful looking amplifier. I owned a Maverick back in the day and even though it was a cosmetic mess it operated flawlessly. If my memory serves me right I was getting 600 watts pep with a couple of wartts of drive and 12 Watts pep. Please take a look if you're in the market. UPDATE! THE PRICE WAS LOWERED TO $316, AND THE SHIPPING ALTHOUGH LISTED AS $100 THE DESCRIPTION ADDS THAT SHIPPING PRICE WILL BE ADJUSTED ACCORDING TO WHERE ONE LIVES. ITS ALSO STILL BEST OFFER. $250 MIGHT LEED THE SELLER TO A COUNTER OFFER OF $275. EVEN IT THE SHIPPING WINDS UP BEING THE $100 @ $375 IMO THE AMPS WORTH IT. IT'S DESCRIBED AS 100% WORKING. I RECENTLY REPLIED TO A POST ABOUT CHANGING CAPS. MAYBE THESE CAPS ARE THE TYPE THE POSTER DESCRIBED. HE SAID IF THEY WORK DON'T CHANGE THEM. I'M HOPING SOMEONE SEE'S THIS AND BUY'S IT. I SHOULDN'T BE BUYING EQUIPMENT WITH MY MEDICAL BILLS DUE, BUT THIS MAVERICK LOOKS SO DAMN CLEAN! I WANT TO PULL THE TRIGGER IN THE WORST WAY. I ACTUALLY DONT NEED IT BUT THESE MAVERICKS ALMOST ALWAYS LOOK LIKE CRAP. I THINK THE GREY COLORED ONE'S ARE FROM THE LATE 60's THROUGH THE LATE 70's WHEN d&a CHANGED THE COLOR TO THE LIGHT BROWN. FOR AN AMP OF IT'S VINTAGE IT LOOKS ABSOLUTELY BEAUTIFUL. PLEASE SOMEONE BUY IT!!! THE LAST THING I NEED TO DO IS SPEND $ ON AN AMP WHEN I ALREADY HAVE 2 TO MANY. I SAID BUY IT. DAMN IT!!! LOL.
https://rover.ebay.com/rover/0/0/0?mpre=https://www.ebay.com/ulk/itm/223628118407
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Shadetree, I know this is an old post, but I noticed in my trials that when L1 choke gets abused/worn the swr climbs..in other circumstances possibly years of use and/or abuse could cause it? A trimmer cap may be enabling the root issue?
My brother, Chris! I've never considered anyone I knew, to be my Elmer, but if I ever need advice, I'll drop you a line, before posting a question. I know chris, to be a modest person, and definitely gives credit, for all the technical hobby, related knowledge he has gained, to all the very knowledgeable members, and now people he considers friends, here on wwdx. 73 God bless you all. Your old friend Jojo.
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That's a good point, the choke doesn't appear to be burnt though. Still running strong without any other problems. I suspect the input tune was never ideal to begin with, because tube radios don't care about swr. In the olden days, people didn't even know that swr was. It has been a while since I used it, I will fire it up tonight.