I want to homebrew a crystal controlled (or VXO) CW Tx, (capable of break-in
operation) that employs a 2E26 tube in the PA. With ICAS operation I can get
27 watts of RF out with a driving power of 0.17 wattts (according to my RCA
sheet). I want most of my "design" efforts and interest to centre around
the PA stage. I think I could cope with that at least.

Can anyone please point me to a suitable solid-state exciter circuit? I want
the Tx to cover any HF band (I'll use plug-in coils). TIA.

"Richard" wrote in message
...
I want to homebrew a crystal controlled (or VXO) CW Tx, (capable of
break-in
operation) that employs a 2E26 tube in the PA. With ICAS operation I can
get
27 watts of RF out with a driving power of 0.17 wattts (according to my
RCA
sheet). I want most of my "design" efforts and interest to centre around
the PA stage. I think I could cope with that at least.

Can anyone please point me to a suitable solid-state exciter circuit? I
want
the Tx to cover any HF band (I'll use plug-in coils). TIA.

Why solid state? Since you're using the 2E26, you already need a high
Voltage supply, and a single stage crystal oscillator can operate from the
same supply without the need for a low Voltage supply for a multistage solid
state exciter. (It's gonna take more than one to get where you want to be.)
A tube crystal oscillator can be found in most old ARRL handbooks, using a
5763 or similar tube. Or, even a 2 stage oscillator buffer/multiplier
utilizing a triode/pentode 6EA8 or similar.

W4ZCB

On Sat, 19 Apr 2008 15:38:31 GMT, Harold E. Johnson wrote:

"Richard" wrote in message
...
I want to homebrew a crystal controlled (or VXO) CW Tx, (capable of
break-in
operation) that employs a 2E26 tube in the PA. With ICAS operation I can
get
27 watts of RF out with a driving power of 0.17 wattts (according to my
RCA
sheet). I want most of my "design" efforts and interest to centre around
the PA stage. I think I could cope with that at least.

Can anyone please point me to a suitable solid-state exciter circuit? I
want
the Tx to cover any HF band (I'll use plug-in coils). TIA.

Why solid state? Since you're using the 2E26, you already need a high
Voltage supply, and a single stage crystal oscillator can operate from the
same supply without the need for a low Voltage supply for a multistage solid
state exciter. (It's gonna take more than one to get where you want to be.)
A tube crystal oscillator can be found in most old ARRL handbooks, using a
5763 or similar tube. Or, even a 2 stage oscillator buffer/multiplier
utilizing a triode/pentode 6EA8 or similar.

IIRC, most any 'simple' 6146 transmitter can be adapted to the 2E26 --
with minor changes in high voltage and grid bias.

The ARRL Handbooks from circa 1955-1975 seemed to always have
a "75 Watt Novice Transmitter" project.

GL ES 73
Jonesy
--
Marvin L Jones | jonz | W3DHJ | linux
38.24N 104.55W | @ config.com | Jonesy | OS/2
*** Killfiling google posts: http://jonz.net/ng.htm

On Sat, 19 Apr 2008, Richard wrote:

I want to homebrew a crystal controlled (or VXO) CW Tx, (capable of break-in
operation) that employs a 2E26 tube in the PA. With ICAS operation I can get
27 watts of RF out with a driving power of 0.17 wattts (according to my RCA
sheet). I want most of my "design" efforts and interest to centre around
the PA stage. I think I could cope with that at least.

Can anyone please point me to a suitable solid-state exciter circuit? I want
the Tx to cover any HF band (I'll use plug-in coils). TIA.

In the fall of 1971, there was a two part article in QST for what may have
been the ultimate CW transmitter. It was solid state up till the driver,
a 6GK6, and then a pair of 6146's. It used the uncommon design, for a cw
transmitter, of a VFO that covered only a fixed range, and then it was
mixed up to the signal frequency. I'm working from the 1972 Handbook, but
I seem to recall the two part nature of the original had the first part
as a simpler version that was expanded in the second part.

But any existing solid state transmitter is going to put out more than
you'll need for the 2E26. Just pick a low power one and build it.


Michael VE2BVW

"Michael Black" wrote in message
mple.org...
On Sat, 19 Apr 2008, Richard wrote:

I want to homebrew a crystal controlled (or VXO) CW Tx, (capable of
break-in
operation) that employs a 2E26 tube in the PA. With ICAS operation I can
get
27 watts of RF out with a driving power of 0.17 wattts (according to my
RCA
sheet). I want most of my "design" efforts and interest to centre around
the PA stage. I think I could cope with that at least.

Can anyone please point me to a suitable solid-state exciter circuit? I
want
the Tx to cover any HF band (I'll use plug-in coils). TIA.

In the fall of 1971, there was a two part article in QST for what may have
been the ultimate CW transmitter. It was solid state up till the driver,
a 6GK6, and then a pair of 6146's. It used the uncommon design, for a cw
transmitter, of a VFO that covered only a fixed range, and then it was
mixed up to the signal frequency. I'm working from the 1972 Handbook, but
I seem to recall the two part nature of the original had the first part
as a simpler version that was expanded in the second part.

But any existing solid state transmitter is going to put out more than
you'll need for the 2E26. Just pick a low power one and build it.


Michael VE2BVW

I'm minded to have the PA valve input circuit have an impedance of 50 Ohms.
I need to fiure out then what the input circuit for the 2E26 would look
like. I've no idea at the moment, not being much of a homebrewer at present.

FYI: THe 2E26 is a good small rugged tube. It was used as final in
the Spy Sets used by the clandestine community in the cold war days.
I have one of the sets, and it will literally tune into anything and
work off almost any power source. It is crystal controlled, but I
don't have any schematic.

One of the older ARRL workbooks will have lots of circuits for the
2E26 tube, circa 1950-1960.




On Sat, 19 Apr 2008 11:36:00 +0100, "Richard"
wrote:

I want to homebrew a crystal controlled (or VXO) CW Tx, (capable of break-in
operation) that employs a 2E26 tube in the PA. With ICAS operation I can get
27 watts of RF out with a driving power of 0.17 wattts (according to my RCA
sheet). I want most of my "design" efforts and interest to centre around
the PA stage. I think I could cope with that at least.

Can anyone please point me to a suitable solid-state exciter circuit? I want
the Tx to cover any HF band (I'll use plug-in coils). TIA.

If the 2E26 is operating class C, I think you'll have a problem generating
enough voltage swing at the 2E26 grid unless you use tuned circuits to step
up the SS drive circuit's output. I have kinda similar set up, DDS VFO
drives SS broadband chain drives (1:4 stepup here) 6CL6 (tuned circuit here)
drives 6146.
Bob
kb8tl


"Richard" wrote in message
...
I want to homebrew a crystal controlled (or VXO) CW Tx, (capable of
break-in
operation) that employs a 2E26 tube in the PA. With ICAS operation I can
get
27 watts of RF out with a driving power of 0.17 wattts (according to my
RCA
sheet). I want most of my "design" efforts and interest to centre around
the PA stage. I think I could cope with that at least.

Can anyone please point me to a suitable solid-state exciter circuit? I
want
the Tx to cover any HF band (I'll use plug-in coils). TIA.

On Apr 25, 6:09*am, "CP" wrote:
If the 2E26 is operating class C, I think you'll have a problem generating
enough voltage swing at the 2E26 grid unless you use tuned circuits to step
up the SS drive circuit's output. I have kinda similar set up, DDS VFO
drives SS broadband chain drives (1:4 stepup here) 6CL6 (tuned circuit here)
drives 6146.
Bob
kb8tl

Right. The 2E26 needs about 80-120V pk-pk on the grid (depending on
plate voltage and power output), at a couple hundred mW.

Mike

Aaah, I see. If I try to use passive grid input circuit how am I going to
get the required voltage swing on the grid which could be in the order of
80-120V pk-pk? Noted thanks.



"CP" wrote in message
. ..
If the 2E26 is operating class C, I think you'll have a problem generating
enough voltage swing at the 2E26 grid unless you use tuned circuits to
step up the SS drive circuit's output. I have kinda similar set up, DDS
VFO drives SS broadband chain drives (1:4 stepup here) 6CL6 (tuned circuit
here) drives 6146.
Bob
kb8tl


"Richard" wrote in message
...
I want to homebrew a crystal controlled (or VXO) CW Tx, (capable of
break-in
operation) that employs a 2E26 tube in the PA. With ICAS operation I can
get
27 watts of RF out with a driving power of 0.17 wattts (according to my
RCA
sheet). I want most of my "design" efforts and interest to centre around
the PA stage. I think I could cope with that at least.

Can anyone please point me to a suitable solid-state exciter circuit? I
want
the Tx to cover any HF band (I'll use plug-in coils). TIA.

On Apr 25, 6:42*pm, "Richard" wrote:
Aaah, I see. If I try to use passive grid input circuit how am I going to
get the required voltage swing on the grid which could be in the order of
80-120V pk-pk? Noted thanks.

I imagine that's why the hybrid rigs of the past that used tube finals
also used a tube driver like a 6CL6 or 12BY7. Just easier to get the
required voltage with a tube, and they had the HV anyway for the
finals. You can certainly get on the air with a two-tube rig - all
the handbooks of the era had them. If you want to rethink a tube
oscillator/driver here are some good tube choices

6AG7
6CL6
5763
6AH6
6AC7
12BY7 (expensive!)

You should also consider joining the glowbugs email list, where ham
radio tube homebrew is king. Google should pull up the info to sign
up. They will definitely get you on the air.

Mike