[mordy]

Let’s do a scientific test, but I need your help to set up the parameters. Burned in tubes, leave them on for one hour, playing music, no fans on, temperature measured at hottest spot in tube. OK? I can use one pair of Bendix graphite plate and a pair of Sylvania regular plates.

Said and done. Put in a pair of Bendix graphite plate 6080 for an hour and measured the hotspot in the tube; then the same with a pair of Sylvania 6080. Driver tubes are a pair of Japanese NEC 6SN7GTB relabled Channel Master.
Played piano music; room temperature 25C.
I do want to point out that rarely do two tubes measure identical temperatures; in addition the temperature within the tube varies in different spots. The infrared thermometer has a little red dot where it hits the object and I wave it slowly back and forth for the highest reading which the thermometer locks on to.
Sylvania 6080 - the tubes are a little different but sound the same:

Bendix: 118/120C
Sylvania: 98/99C
Why they measure different when they both draw 2.5A I leave for others to figure out.

 

[Shane D]

Said and done. Put in a pair of Bendix graphite plate 6080 for an hour and measured the hotspot in the tube; then the same with a pair of Sylvania 6080. Driver tubes are a pair of Japanese NEC 6SN7GTB relabled Channel Master.
Played piano music; room temperature 25C.
I do want to point out that rarely do two tubes measure identical temperatures; in addition the temperature within the tube varies in different spots. The infrared thermometer has a little red dot where it hits the object and I wave it slowly back and forth for the highest reading which the thermometer locks on to.
Sylvania 6080 - the tubes are a little different but sound the same:

Bendix: 118/120C
Sylvania: 98/99C
Why they measure different when they both draw 2.5A I leave for others to figure out.

Don't have any 6AS7G's sitting around do you?

 

[mordy]

Don't have any 6AS7G's sitting around do you?

I do - what to you want me to measure? 6080 vs 6AS7G?

 

[No Deal]

I have seen GEC 6AS7G rebranded as Haltron......

Are these the real deal? Way overpriced?

https://www.ebay.com/itm/254195578638?ssPageName=STRK:MEBIDX:IT&_trksid=p2060353.m1438.l2649

 

[L0rdGwyn]

Are these the real deal? Way overpriced?

https://www.ebay.com/itm/254195578638?ssPageName=STRK:MEBIDX:IT&_trksid=p2060353.m1438.l2649

Those are Russian.

 

[cddc]

Said and done. Put in a pair of Bendix graphite plate 6080 for an hour and measured the hotspot in the tube; then the same with a pair of Sylvania 6080. Driver tubes are a pair of Japanese NEC 6SN7GTB relabled Channel Master.
Played piano music; room temperature 25C.
I do want to point out that rarely do two tubes measure identical temperatures; in addition the temperature within the tube varies in different spots. The infrared thermometer has a little red dot where it hits the object and I wave it slowly back and forth for the highest reading which the thermometer locks on to.
Sylvania 6080 - the tubes are a little different but sound the same:

Bendix: 118/120C
Sylvania: 98/99C
Why they measure different when they both draw 2.5A I leave for others to figure out.

Sorry, I don't argue with uneducated person, you win @mordy !

 

[Shane D]

I do - what to you want me to measure? 6080 vs 6AS7G?

Yes please. That was the question I had asked earlier, "Is there a difference temperature wise?"

 

[L0rdGwyn]

Max temperature only means the said tube can stand such temperature, so yeah, with stronger graphite plates Raytheon graphite plate 6080 can stand 100c more than RCA 6080 regular plates. But in actual circuits RCA regular plate 6080 and Raytheon graphite plate 6080 will consume the same amount of heater current (2.5A), and the same amount plate/grid current in the same circuit/amp, hence they will generate the same amount of heat. Max temp on the tube data sheet is only the max rating, it has nothing to do with actual/working heat generated.

I don't put my faith on feeling or guts, I put my faith on science and data...

Let’s do a scientific test, but I need your help to set up the parameters. Burned in tubes, leave them on for one hour, playing music, no fans on, temperature measured at hottest spot in tube. OK? I can use one pair of Bendix graphite plate and a pair of Sylvania regular plates.

Assuming the tubes measure roughly the same and will be at the same operating point in the same circuit - meaning the same plate-to-cathode voltages, grid-to-cathode voltages, and plate currents - the heaters and the plates will dissipate the same amount of power in two different models.

However, the plates have different material and physical construction, as such they are going to have different thermal resistance, °C/W, increase in material temperature for unit of power dissipated.

So the power dissipation is the same, but the temperature will different based on the thermal resistance of the internal structure.

Also, there is no "grid current", this is class A1, the grid is always negative relative to the cathode. Looking into the grid from the previous stage will present an impedance in the tens of megaohms range, it won't draw any current. The only current contributing to the increase in tube temperature will flow through the heaters and from plate to cathode.

 

[mordy]

Are these the real deal? Way overpriced?

https://www.ebay.com/itm/254195578638?ssPageName=STRK:MEBIDX:IT&_trksid=p2060353.m1438.l2649

The last picture shows the dual inverted saucer getters which means that they are Russian Svetlana tubes. Here is a link to one for sale now:
https://www.ebay.com/itm/194998609015?hash=item2d66d2a477:g:gnAAAOSwHc1iUswR
Overpriced? You bet! Maybe a 10th of the price for a pair.

 

[bcowen]

Are these the real deal? Way overpriced?

https://www.ebay.com/itm/254195578638?ssPageName=STRK:MEBIDX:IT&_trksid=p2060353.m1438.l2649

In addition to what @L0rdGwyn and @mordy already posted, the seller is 'wege_high_tubes'. He has a lengthy reputation of pricing tubes at 5x - 10x the going market price. He knows very well those are not Telefunkens, or he'd have them priced at $4500. Best recommendation is to steer very clear of anything he's listing.

 

[hmscott]

I saw those Halton's, and thanks to the previous detailed descriptions here I knew it was a Svetlana

How about this one? Did Telefunken actually make this 6080 in their Ulm plant under license from RCA or another manufacturer? The seller goes into a discussion of the origin of this tube and others not made by Telefunken but instead rebranded by Telefunken, www-tubes.rs states that this 6080 was produced by Telefunken:
https://www.ebay.com/itm/253791647315

"Auction is for one (1 pcs) extremely rare genuine Telefunken 6080 / 6AS7 / 5998.
This tube is very scarce. You can find many other types rebranded Telefunken 6080 like General Electric, RTC France, Sylvania, ... All of them come in original Telefunken boxes.
Someone who is not deeply interested in tube production details for years could make mistake easily.
This one is made in Ulm tube plant and it's clearly different to fakes in many details. The most important details are unique Telefunken's thick ring getters, two of them.
The tube is tested with 100V on plates and -24V on grids. This tube tests 130/136 mA, very strong example, like NOS, with lot of life left.
Please pay attention that guiding pin is broken as it is shown on photos!"


"On eBay
If you buy directly, the prices are 12% lower and the items will be declared as “old radio parts”, low value, so you will need to pay just symbolic VAT and tax amount. Place your orders to nostubes@gmail.com please."

What I find most odd is that they blatantly go against eBay Policy of selling eBay listed items off-site, strange...
https://www.tubes.rs/ebay-listings/

 

[cddc]

Assuming the tubes measure roughly the same and will be at the same operating point in the same circuit - meaning the same plate-to-cathode voltages, grid-to-cathode voltages, and plate currents - the heaters and the plates will dissipate the same amount of power in two different models.

However, the plates have different material and physical construction, as such they are going to have different thermal resistance, °C/W, increase in material temperature for unit of power dissipated.

So the power dissipation is the same, but the temperature will different based on the thermal resistance of the internal structure.

Also, there is no "grid current", this is class A1, the grid is always negative relative to the cathode. Looking into the grid from the previous stage will present an impedance in the tens of megaohms range, it won't draw any current. The only current contributing to the increase in tube temperature will flow through the heaters and from plate to cathode.

LG, I can't believe an educated person like you with a Dr. degree would argue something that is factual...you think I'm as gullible as some uneducated person does...I'm so disappointed in you!

Okay, let's talk about thermal resistance and the law of conservation of energy!

So what is the thermal resistance that you're trying to base your argument on? It's an object's resistance to heat conductance. Yes, some materials conduct heat faster, some slower, just like the Raytheon graphite plate 6080 takes longer to warm up, and the regular plate 6080 warms up much faster. But have you considered the law of conservation of energy?!!!

As long as the same 2.5A heater current is drawn, and the same amount of plate current and grid current (yes, I intentionally list grid current here just in case someone will be nit-picky on the subject! I will elaborate later) are going through both the graphite-plate and regular-plate tubes, the same amount of total heat will be generated, which can be calculated by the following equations, Total power consumed = heater power consumption + plate power consumption + grid power consumption = I_heater x V_heater + Ip x Vp + Ig x Vg. The 6 parameters on the right hand side of the equation will be the same for both Ray graphite-plate 6080 and regular-plate 6080, hence the total power consumed will be the same for both tubes ( and total heat generated = total power consumed - power consumed by the load on tube, will also be same since load will be the same)! Yes, Ray graphite-plate 6080 will reach normal thermal operating temperature slower than regular 6080 does because of its higher thermal resistance, but it will eventually get there (some folks say graphite-plate 6080 needs 10-30mins to warm up), and what's more important, the total heater generated by both 6080 tubes will be the SAME, that's defined by the equations I listed above and the law of conservation of energy.

Now, let me elaborate why I intentionally listed grid current there previously. Yes, most tubes run on negative grid voltage on their grids, hence their grid current will be close to 0, but let's not forget that some tubes do run on positive grid voltages, so there will be measurable grid current on them! And even under the negative grid voltage mode, some electrons will go astray and hit the grid by chance, hence will generate grid current theoretically (though this current is almost 0 and is negligible). So if I did not list grid current there, some guy will be nit-picky on it. And even I did include the grid current there, someone is still trying to be nit-picky on it

 

[cddc]

I saw those Halton's, and thanks to the previous detailed descriptions here I knew it was a Svetlana

How about this one? Did Telefunken actually make this 6080 in their Ulm plant under license from RCA or another manufacturer? The seller goes into a discussion of the origin of this tube and others not made by Telefunken but instead rebranded by Telefunken, www-tubes.rs states that this 6080 was produced by Telefunken:
https://www.ebay.com/itm/253791647315

"Auction is for one (1 pcs) extremely rare genuine Telefunken 6080 / 6AS7 / 5998.
This tube is very scarce. You can find many other types rebranded Telefunken 6080 like General Electric, RTC France, Sylvania, ... All of them come in original Telefunken boxes.
Someone who is not deeply interested in tube production details for years could make mistake easily.
This one is made in Ulm tube plant and it's clearly different to fakes in many details. The most important details are unique Telefunken's thick ring getters, two of them.
The tube is tested with 100V on plates and -24V on grids. This tube tests 130/136 mA, very strong example, like NOS, with lot of life left.
Please pay attention that guiding pin is broken as it is shown on photos!"


"On eBay
If you buy directly, the prices are 12% lower and the items will be declared as “old radio parts”, low value, so you will need to pay just symbolic VAT and tax amount. Place your orders to nostubes@gmail.com please."

What I find most odd is that they blatantly go against eBay Policy of selling eBay listed items off-site, strange...
https://www.tubes.rs/ebay-listings/

This one is the real deal, it's indeed a genuine Telefunken 6080.

Telefunken did produce some 6080 tubes, but in very small quantity.

 

[mordy]

This one is the real deal, it's indeed a genuine Telefunken 6080.

Telefunken did produce some 6080 tubes, but in very small quantity.

Looks like an honest seller - he also lists rebranded Telefunken 6080 tubes clearly as RCA made.
https://www.ebay.com/itm/255313837773?hash=item3b71e3fecd:g:swsAAOSwoa1h1KMo

And here is another Telefunken branded GE tube:
https://www.ebay.com/itm/264912109312?hash=item3dadfdff00:g:KZcAAOSwunJflVJc

The back of the tube has the telltale GE dots:

Perhaps the easiest way to tell real ones apart from fakes is to look for a double top mica:

 

[Galapac]

This one is the real deal, it's indeed a genuine Telefunken 6080.

Telefunken did produce some 6080 tubes, but in very small quantity.

Yes, you have to be careful buying Telefunken 6080s.
I bought some years ago and educated myself on what was genuine.

For example here is a bad fake:
https://www.ebay.com/itm/255313837773?hash=item3b71e3fecd:g:swsAAOSwoa1h1KMo

• Bad date code
• 6AS7W marking (really?)
• no ”Made in Germany” marking
• single top mica(Telefunkens have two)
• new boxes
• and worst of all GE markings to boot

Many took Thomson France 6080WA tubes and faked them to look like Telefunkens but the easiest give away is bad date codes or many tubes having the same date code since the forgers were lazy and didn’t bother to change the codes.