• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

Those Magnificent Television Tubes

This tube features a conventional control grid. There's a frame grid succedessor, though, the EF184/6EJ7 - same pinout, shorter envelope, much higher gm, lower noise figures. Both the EF80 and the EF184 were designed for IF strips in European TV sets. Their remote cutoff pendants are EF85/6BY7 and EF183/6EH7, respectively.

Best regards!

thank you...
 
I was expecting George to say 4D32 for the maximum Watts.....i wonder what the 4d32 can really do in terms of power.....

I briefly explored the power limits of the 4D32 in the 6L6GC in AB2 thread. They are seen in post #654.

I did not consider them for this amp because I only have 6 of them and my amp will use at least 8 tubes plus spares. I have seen as much power flow from 35LR6's, and I haven't been there yet, but I believe that under the conditions that I will likely use, the 36LW6 will make more power based on it's peak cathode current capabilities. Physical size is also a factor.

The 4D32 made 200 watts on 650 volts into a 3300 ohm load. The power went to 250 watts when I changed the load to 2500 ohms, but the plate efficiency went down indicating more power being wasted in the tube. The optimum load seems to be in the 3300 ohm range, so more power could be found with more B+ voltage, but 650 volts is already over the published specs. Based on looks and the fact that this is an RF tube designed for Collins, those ratings are probably very conservative. My bench supply only goes to 650 volts, so that is the limits of my testing ability for now.....and above the ratings for my existing OPT's.

I have seen 525 watts flow through these OPT's with 4 X 35LR6 but they were at the edge of pale glow in a dark room after a minute or two. That may be OK since I don't plan to listen to 1 KW of continuous sine waves!

I have been talking about this for several years, but preliminary work on the project has started. I will start a new thread about it in the Tubes / Valves forum some time in the next few days.
 
The microscope results

Since I promised, here is it:
The microscope is a toy type, but suceed to show grid wires
I need to touch the microscope lens (very close) for seeing the wires.
The 'scope manual says 200x magnification, but I don't believe.
Really are a VERY small gauge...
I put a HP old display-in-a-chip (what a waste of semiconductor surface...). It have a integral lens, and real chip size is less than 1x2mm. Note the very huge bond wires, in comparision to this tube (like smoking-amp said)
Most EPROM out here have also bond wires larger tha that.
Of course, modern IC probably have more fine bond wires
 

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How lucky you are! This valve, among others, has been made in a manageable amount of about 1.500 pc., therefore it is very scare and expensive - if one ever gets his hands on some of them.

I didn't want anybody here to destruct his valuable tubes, I've just been kidding :D.

The EL3010 is among the power tubes with the highest gm figures that I'm aware of.

Best regards!
 
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While looking around on my hard drive for something else, I found the example that makes me distrust the entire lot of 35LR6's that I have. There are some good tubes in there but I would need to do an extreme test on each tube.

This one met the hammer. A good tube has a twist on the tabs at the top of the plate where it comes through the top mica. This keeps the mica from popping off. This tube had no such twist, and neither do most of the other tubes. I got 45 35LR6 tubes in a cardboard box at a hamfest and they were cheap. Perhaps these had been stress tested by UPS somewhere in their history.

You see some unusual characters at a hamfest, but Major Tom?
 

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DIYBras: good idea with the mm scale

Here are the 6JC6 (3.1 Watt diss. RF), 12HL7 (10 Watt diss. Video), E130L (27.5 Watt diss.), and 21JV6 (18 Watt diss. TV Sweep) again with mm scales.

Counting both wires at the 1 mm end points, looks like 19 wires for the 6JC6, 9.5 wires for the 12HL7, 4.5 wires for the E130L, and 9 wires per 5 mm for the the 21JV6

so wires per mm would be 1 less:
6JC6 18 wires/mm
12HL7 8.5 wires/mm
E130L 3.5 wires/mm
21JV6 1.6 wires/mm

There is a 12GN7 that is identical to the 12HL7 (21000 gm) except it has 36000 gm. So I would guess it has 36/21 x 8.5 = 14.57 wires/mm

-----------------------

EL3010 obviously are scarce. $125

12HL7 and 6JC6 on the other hand seem to be over-abundant TV tubes. Both made the $1 list at ESRC. A couple hundred of each in a box here.

Using 5 curve tracer selected 12HL7 in parallel, gives me 50 Watt diss. and 105,000 gm. for $5 (OK, some sockets too)

pic 4: 12HL7 in triode

-------

pic 5: train tracks near George's house after he got 600 Watts out of the 6LW6 :eek::D:D

pic 6: power line to Tubelab now :D:cool:

..
 

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I looked at some Sylvania 35LR6 tubes here and they do seem rather lacking in twisted top plate pins. Not only 35LR6 even, 24JE6 too and some others. Many have a just barely noticeable slight twist too. Like it was meant to just hold some parts together until it got handed to the next person on the assembly line. They may be depending on the bent tab on the beam plate to hold them together. Cost savings? Efficiency? In a hurry?

I can imagine they didn't test for present day UPS delivery 6 ft drop tests. The delivery guy last week fell over just walking to the door with a heavy box. And the 1st Tek Curve Tracer I ordered years ago arrived with the CRT busted and the box crushed. It went back.
 
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the 1st Tek Curve Tracer I ordered years ago arrived with the CRT busted

They seem to kill many heavy packages that get delivered here. I have talked to the FedEx and UPS drivers that deliver here and asked them to ring the doorbell when they have a heavy delivery for this house and I will meet them at the truck with a hand truck or carry the package myself. They are pretty good about that, but I had 135 pounds coming in 3 boxes including a HP8664 RF signal generator that weighs in at 85 pounds. I heard a crash on the front porch and went out the door to see a UPS truck pulling away. The signal generator had the box caved in on one side.

I promptly picked it up put it in my car and drove to the UPS office where we opened the box. The front panel was smashed and one VFD was obviously broken. UPS said that the unit was not properly packaged, something that heavy should have been crated. The EBAY seller said "you paid for a parts unit, that's what you got." The picture clearly showed two working VFD's, but the seller, and Paypal agreed that I got what I paid for. I still managed to fix the unit, but I had to buy another front panel.

I have seen a lot of corner cutting in vacuum tubes made near the end of the vacuum tube production era. Sylvania / Philips / ECG seemed to do this the most, and resorted to a lot of "glass stuffing" to fulfill existing contracts. I have seen a lot of different guts stuffed into a bottle and labeled "807." There were some 6BG6's with 7027A guts inside, and even some 6B4's (a DHT) with triode connected 6AV5's ( a TV sweep pentode) guts inside. I have also seen some pretty crummy tubes quality wise in Sylvania ECG boxes.
 
I had a "minty" and spare HP35670A and sold it to a fellow in Boston. We exchanged info and he drove down here to pick it up in order to avoid shipping. Offered him coffee, eggs n/ bacon but he wanted to get it back up there before dinner! (I had scored a SR785 which is much easier to work with and wasn't unhappy to part with the HP.)
 
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So the question is, is this a true Sylvania tube or a GE?


While looking around on my hard drive for something else, I found the example that makes me distrust the entire lot of 35LR6's that I have. There are some good tubes in there but I would need to do an extreme test on each tube.

This one met the hammer. A good tube has a twist on the tabs at the top of the plate where it comes through the top mica. This keeps the mica from popping off. This tube had no such twist, and neither do most of the other tubes. I got 45 35LR6 tubes in a cardboard box at a hamfest and they were cheap. Perhaps these had been stress tested by UPS somewhere in their history.

You see some unusual characters at a hamfest, but Major Tom?