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Author Topic: 2e26 tube PA  (Read 8460 times)
G3RZP
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Posts: 4586




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« Reply #15 on: November 24, 2012, 12:55:22 AM »

2E26 was around in 1948. 6146 didn't arrive until 1953.
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9A5BDP
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« Reply #16 on: November 26, 2012, 12:09:14 PM »

It's 2e26 tube originated regarding industrial/military or ham needs?
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G3RZP
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« Reply #17 on: November 27, 2012, 04:20:44 AM »

Industrial, I believe.
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9A5BDP
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« Reply #18 on: November 27, 2012, 11:52:03 AM »

I ask this because of nonstandard name (not like industrial tubes), thanx for information
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WB6BYU
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« Reply #19 on: November 27, 2012, 12:36:08 PM »

Most tube manufacturers had their own numbering systems that were used for tubes that
they developed.  Only those devices that were particularly successful (or were going to be
delivered to the military or other customer who required it) had "Standard" type numbers
assigned to them (often after the device had been in use for a while.)

The same is true of transistors today:  many manufacturers have parts that aren't
registered with one of the several different Standards, so carry the company's own
part number.  But if such a part is to be used in US Military equipment, for example,
it must be registered with JEDEC and assigned a "2Nxxxx" part number.
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N3QE
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« Reply #20 on: November 27, 2012, 12:42:11 PM »

I ask this because of nonstandard name (not like industrial tubes), thanx for information

The wonderful things about standards, is there are so many to choose from!!!!

The 2E26 number comes from the RMA 1942-1944 system. It is very standardized. First number is the heater power; 2 means less than 10 watts. The letter is type of device; E is a pentode. And the last digits are a serial number, starting with 21.

Incidentally... there are some other devices widely available to this day from the same numbering system. e.g. 1N34 means this: 1 means no heater power. N means crystal rectifier. 34 is a serial number. Thus... the number for the 1N34 germanium diode comes from the exact same system as the 2E26 tube.

See Sibley's _Tube Lore_, or http://en.wikipedia.org/wiki/RMA_tube_designation
« Last Edit: November 27, 2012, 12:44:46 PM by N3QE » Logged
9A5BDP
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« Reply #21 on: November 28, 2012, 11:53:37 AM »

Thanx for a lot of tech informations. I also have several pieces of 2c22 tube (for my audio hobby) and finaly I have descriptions for that standard-nonstandard tube marking system.

So back to workbench and hot soleding iron...
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VE3LYX
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Posts: 141




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« Reply #22 on: December 24, 2012, 06:56:53 PM »

I have a single tube amp on my homebrew Screen grid modulated transceiver. The transceiver is very low power so I had to build a PA for it. I used a variant of the 6146 as well.(6293)
Build a tank circuit coming in driven by a 4 turn loop in the centre of the tank coil.  For 40 m ten turns always works to get you in the ball park You can pad from there or tune . I used a dual gang 365pf from an ac dc radio (aka American 5) . I use the series style for 40m and parallel style for 80m . It works almost perfect and requires only small change when changing bands from my favourite frequencies. Set your grid resistor and feed in with a small RF style cap from the top of your input tank. Put a 52 bulb in the cathode circuit to keep the thing from running too strong in no signal mode. Also works great for tune up and acts as a safety fuse should something go wrong. Make a parasitic choke from some heavier copper wire and a low value 2 watt resistor. 5 turns usually is fine. Feed the plate with a Rf choke , I make mine from an old 5 watt wirewound resistor removing the old resistance wire and rewinding many turns of #22. Put on what you think is enuf then add 20 more turns. It will work just fine. Couple that to the plate lead and parasitic choke. Feed the output tank or Pi with a 1kv .01 . Take the screen off the plate feed before the RFC choke (PSupply side) I think mine is 27k but I would have to check. Took two tries. I was looking for 200 Volts screen.
Cathode circuit is fed from ground as is grid. And cathode goes from ground to 52 bulb then the cathode. I also like a switch in the cathode circuit. I use a good quality spst rated at 5 amps 250 volts so I can pop the amp out when on long standby. It works pretty good. I run around 327 volts under load. I use a gimmick cap between grid and plate for neutralizing but so far it hasnt been a problem. Gimmick is two lengths of insulated hook up wire twisted together but not actually connected . This run has a Pi output tank but I actually prefer a normal tank. I just had to try it to see if I liked the difference.
I wouldnt worry too much about a schematic. Get the DC voltages right. Put the RFchokes in , make the in and out tanks  then wire the RF stuff and you are away.
Don VE3LYX
 
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