Hi,

807 == 6L6 for RF in a 5-pin socket.

Or do you need a 6L6 specifically?

Frequency would be helpful as I have some 6L6 for guitar amps I can test
for suitability.


Cheers!
__
Gregg

Kevin Dooks wrote:
Anyone have any thoughts on which 6L6GC being currently produced would
be best for RF work ?


TIA

I've used the cheap eastern block 6l6's on 40 & 80m without any
problems, if you need to use the higher bands you would be better off
using a 807 (same valve but with a top cap anode)

http://cgi.ebay.co.uk/10x-Tubes-6L6_W0QQitemZ300266924970QQcmdZViewItem?hash=item3 00266924970&_trkparms=39%3A1|66%3A2|65%3A1|240%3A1 318&_trksid=p3286.c0.m14

Far better quality than the new production Chinese version.


Steve H

In article ,
Kevin Dooks wrote:
Anyone have any thoughts on which 6L6GC being currently produced would
be best for RF work ?

Check the datasheets and pick the one with the lowest interelectrode
capacitance.

The higher power ones (like the Sovtek 6881WXGT) will probably tend to
have higher capacitance because of the larger plate area.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

Anyone have any thoughts on which 6L6GC being currently produced would
be best for RF work ?


TIA

Kevin Dooks wrote:
On Mon, 20 Oct 2008 19:44:09 -0300, Kevin Dooks
wrote:

Anyone have any thoughts on which 6L6GC being currently produced would
be best for RF work ?


TIA

Sorry, I should have given more info. This home-brew CA
( Canoe Anchor ) covers 40 thru 10M, CW and phone and runs 400 ish
volts on the plate. There are space limitations, height including
envelope and base con't exceed 3 inches max and envelope diameter
can't exceed 1.65 inches due to cabinet restrictions.

Would LOVE to use an 807 or 6FL6 or similar but I just don't have the
room.

TIA

Aren't most 6L6 variants taller than 3" by a good bit?

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

Do you need to implement control loops in software?
"Applied Control Theory for Embedded Systems" gives you just what it says.
See details at http://www.wescottdesign.com/actfes/actfes.html

Kevin Dooks wrote:

Sorry, I should have given more info. This home-brew CA
( Canoe Anchor ) covers 40 thru 10M, CW and phone and runs 400 ish
volts on the plate. There are space limitations, height including
envelope and base con't exceed 3 inches max and envelope diameter
can't exceed 1.65 inches due to cabinet restrictions.

Would LOVE to use an 807 or 6FL6 or similar but I just don't have the
room.

Hi,

You might try a 5881 tube. It's shorter than the normal 6L6GC's.
5881 seated height is 2.9"
Height including base pins is 3.938", diam 1.438"

I would buy a new old stock GE or RCA 5881,
in case the current production
imports are not suited for rf, since production is now aimed
at the electric guitar amplifier market.

The 5881 has 23W max plate dissipation. The original series
6L6/ 6L6G/ 6L6GA/ 6L6GBGB had 19W max plate dissipation,
and the 6L6GC had 30W.

73,
Ed Knobloch

On Mon, 20 Oct 2008 19:44:09 -0300, Kevin Dooks
wrote:

Anyone have any thoughts on which 6L6GC being currently produced would
be best for RF work ?


TIA

Sorry, I should have given more info. This home-brew CA
( Canoe Anchor ) covers 40 thru 10M, CW and phone and runs 400 ish
volts on the plate. There are space limitations, height including
envelope and base con't exceed 3 inches max and envelope diameter
can't exceed 1.65 inches due to cabinet restrictions.

Would LOVE to use an 807 or 6FL6 or similar but I just don't have the
room.

TIA

Kevin Dooks wrote:

Sorry, I should have given more info. This home-brew CA
( Canoe Anchor ) covers 40 thru 10M, CW and phone and runs 400 ish
volts on the plate. There are space limitations, height including
envelope and base con't exceed 3 inches max and envelope diameter
can't exceed 1.65 inches due to cabinet restrictions.

Hi,

If you can't submount the octal socket, even a 5881 won't fit.
Have you considered a pair of 5763 9 pin miniature
transmitting tubes in the final? Each has 12W max plate dissipation,
so a pair would be rated for the same power as a 6L6.
They are small, so not as forgiving of an overload, though.

An 8121 tube would fit easily, but it requires a 12V heater,
and the sockets can be expensive. It's finned for a transverse
blower, but at 400V class C, it might not need a blower.
I've bought 8121's on ebay for around $10, a bargain
compared to the pricey 8122, which is the same tube
with a bigger plate dissipation rating (and which requires
through-the-socket cooling).

If you are willing to pressurize the chassis, a 4X150A
or 4CX250B would fit fine, but your blower might be as large
as the rest of the rig.

73,
Ed Knobloch

Edward Knobloch wrote:
Kevin Dooks wrote:

Sorry, I should have given more info. This home-brew CA
( Canoe Anchor ) covers 40 thru 10M, CW and phone and runs 400 ish
volts on the plate. There are space limitations, height including
envelope and base con't exceed 3 inches max and envelope diameter
can't exceed 1.65 inches due to cabinet restrictions.

If you can't submount the octal socket, even a 5881 won't fit.
Have you considered a pair of 5763 9 pin miniature
transmitting tubes in the final? Each has 12W max plate dissipation,
so a pair would be rated for the same power as a 6L6.
They are small, so not as forgiving of an overload, though.

On 160M, you should be able to get more power out of a 6L6 than a single
5763, but by the time you get up to 20M, the 5763 will be putting out a good
bit more than the 6L6. The shunt capacitance on the 6L6 kills you.

An 8121 tube would fit easily, but it requires a 12V heater,
and the sockets can be expensive. It's finned for a transverse
blower, but at 400V class C, it might not need a blower.
I've bought 8121's on ebay for around $10, a bargain
compared to the pricey 8122, which is the same tube
with a bigger plate dissipation rating (and which requires
through-the-socket cooling).

The 8121 is a really cool gadget, and ten bucks is hard to beat. It is
surprisingly rugged, and if you only want to run HF you can make your own
socket.

If you are willing to pressurize the chassis, a 4X150A
or 4CX250B would fit fine, but your blower might be as large
as the rest of the rig.

Last time I used a 6L6 as a final, I had to submerge the whole chassis in
transformer oil to cool it down. I was getting less than 2W on 10M with
the plates glowing bright red. That was... well... a long time ago....
it seemed like a good idea at the time... and it worked great on 80M!
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."