No Transformer Amp

[supro66]

This thing could not work 



6KD6 tubes need 900 volts on the plates 15 tubes  :shocked:

One big Transformer

[PRR]

> 6KD6 tubes need 900 volts

No... that's a maximum.

They were designed for 150V TV sets.

They will pass large current at low voltage. Over 1 Amp with 45V plate (but 160V 110mA on G2).

> 15 tubes

Yeah, and they are $40-$60 each with a steady market in radio transmitters.

I estimate it works near 200mA per tube, 3 Amps for the whole amp (which disagrees with the 150mA on the plan). Maybe 800 Watts total dissipation for ~~30 Watts output. $700 of tubes.

The suggested 6V 5A heater power would not warm two 6KD6 (2.85A each!).

[Shrapnel]

What about the 6DK6 tubes?

Source of data: http://www.nj7p.org/Tube4.php

"Miniature type used as if amplifier tube in color and black-and-white television receivers. Requires miniature 7-contact socket."

Preferred Substitutes ......................... 6CB6 6CF6 6DE6
Substitutes ................................... 6BZ6 6HQ6


Heater Voltage ................................ 6.3 V
Heater Current ................................ 0.3 A

Maximum Ratings (Design Center Values): Pentode
Plate Voltage ................................. 330 V
Grid No. 2 Voltage ............................ 330 V
Plate Dissipation ............................. 2.3 W
Grid No. 2 Dissipation ........................ 0.55 W

Class A Amplifier
Plate Voltage ................................. 125 V
Grid No. 2 Voltage ............................ 125 V
Grid No. 1 Voltage Derived from
Cathode Bias Resistor ....................... 56 Ω
Plate Resistance (approx) ..................... 350K Ω
Transconductance .............................. 9800 µMho
Plate Current ................................. 12 mA
Grid No. 2 Current ............................ 3.8 mA

Class A Amplifier
Plate Voltage ................................. 300 V
Grid No. 2 Voltage ............................ 150 V
Grid No. 1 Voltage ............................ -6.5 V
Transconductance .............................. 9800 µMho
Plate Current ................................. 12 mA
Grid No. 2 Current ............................ 3.8 mA

The 6KD6 IS a different beast, and not the tube mentioned on that schem.

6KD6
"Duodecar type used as horizontal-deflection amplifier in color and bw tv receivers. Requires duodecar 12-contact socket."

[kagliostro]

Tube Depot sell 6DK6 at $ 3.95 each

http://store.tubedepot.com/nos-6dk6.html

Kagliostro

[supro66]

Tube Depot sell 6DK6 at $ 3.95 each

http://store.tubedepot.com/nos-6dk6.html

Kagliostro

I am going to get 4

I have a Yaesu FT 401-B Ham radio transceiver

There are 2-- 6KD6 tubes for the output

After I retire I plan to put a station on air again

That’s a good price

WRONG WRONG

I went and checked $50.00 for 6KD6 you had 6DK6
http://www.tubedepot.com/nos-6kd6.html

I knew that was to good to be true   

[sluckey]

WRONG WRONG

I went and checked $50.00 for 6KD6 you had 6DK6
http://www.tubedepot.com/nos-6kd6.html

I knew that was to good to be true   

Why are you interested in 6KD6? Your schematic clearly shows 6DK6.

[kagliostro]

I think he has two different interest

one for a Transformer Less amp 6DK6

and other for 6KD6 to be used in his RF transmitter

Kagliostro

[sluckey]

I think he has two different interest

I guess? But the 6KD6 has nothing to do with the topic of this thread or the schematic he posted. I really think he just got the tubes mixed up in the original post.

[supro66]

I think he has two different interest

one for a Transformer Less amp 6DK6

and other for 6KD6 to be used in his RF transmitter

Kagliostro

Yes you are right
I am sorry

I was looking for 6KD6 stuff
I was not paying attention

63 is a tough age for me
I wanted to see a 6KD6 schmatic

[kagliostro]

If you are looking for 6KD6 audio schematics

Traynor YBA - 3 use similar tubes 6KG6

if I'm not wrong 6KD6 = EL519 -- 6KG6 = EL509

http://www.lynx.bc.ca/~jc/700116_YBA3_A.gif

Kagliostro

[PRR]

> What about the 6DK6 tubes?

Dislexya strikes agian.

Then yeah, a bit over 10mA 2W per tube, say 200mA total, 1.6V or 1.13V RMS in 8 ohms is 0.16 Watts output from 40W plate heat and 28W of heaters.

Even if you find tubes and sockets super-cheap, is it worth the work?

[RicharD]

Seems like a transformerless tube power amp is possible but not practical when dealing with any sort of real power.  If it was, Fender & Marshall etc. woulda been doing it already.  OTOH, it's quite doable at lower power and higher impedance.  My headphone amp is transformerless using 6DJ8's as White cathode followers.  It sounds great and drives my cans plenty-o-loud.

[DummyLoad]

use 6AS7/6080 or 6c33 soviet.

--ISO

[supro66]

> What about the 6DK6 tubes?

Dislexya strikes agian.

And I do records on air craft every day

Hours and Drawing numbers for repair parts

I have to watch my P's and Q's

I have transposed numbers like 3753 to 3573  :shocked:

[HotBluePlates]

Seems like a transformerless tube power amp is possible but not practical when dealing with any sort of real power.  If it was, Fender & Marshall etc. woulda been doing it already. ...

You just said a mouthful!

If we had good speakers with an impedance of 200 ohms or so, OTL amps would be more common.

However, there are folks that feel OT's have so many flaws and design problems that they must find a way to eliminate them. That is easily done with solid-state, but difficult and wasteful with tubes.