Can anyone tell me what are the normal plate voltages
used on this tube in the two modes? I'm trying to figure out
what plate transformer to look for or try to cobble up?

I've googled lots of these amplifiers but see no mention
of CW/RTTY mode voltages/currents. It looks like about
3000V on SSB but see not mention of other modes. My SB220
had a tap on primary at the SQR2 point to switch modes,
would that be the same for this tube? What would be good
parameters for CW/RTTY operation?

Thanks.

WA5DXP

Jim wrote:
Can anyone tell me what are the normal plate voltages
used on this tube in the two modes? I'm trying to figure out
what plate transformer to look for or try to cobble up?

I've googled lots of these amplifiers but see no mention
of CW/RTTY mode voltages/currents. It looks like about
3000V on SSB but see not mention of other modes. My SB220
had a tap on primary at the SQR2 point to switch modes,
would that be the same for this tube? What would be good
parameters for CW/RTTY operation?

Thanks.

WA5DXP


You should be OK with 3KV on the anode + 350V on G2 , de-rating for RTTY
will depend more on the amount of cooling air and PSU. Watch the grid
current as it's only rated at 1W max.

Have a look at care and feeding of power grid tubes on the CPI site
(they own Eimac), http://www.cpii.com/library.cfm/9 .

Gerry....

Gerry;

Thanks for the link. The SB220 had a tap on primary, so when you
switched to CW/RTTY you did not have to retune the amp,
which was probably done by others.

I'll check out the site.

Jim







On Sun, 16 Mar 2008 03:13:49 +0000, Gerry
wrote:

Jim wrote:
Can anyone tell me what are the normal plate voltages
used on this tube in the two modes? I'm trying to figure out
what plate transformer to look for or try to cobble up?

I've googled lots of these amplifiers but see no mention
of CW/RTTY mode voltages/currents. It looks like about
3000V on SSB but see not mention of other modes. My SB220
had a tap on primary at the SQR2 point to switch modes,
would that be the same for this tube? What would be good
parameters for CW/RTTY operation?

Thanks.

WA5DXP


You should be OK with 3KV on the anode + 350V on G2 , de-rating for RTTY
will depend more on the amount of cooling air and PSU. Watch the grid
current as it's only rated at 1W max.

Have a look at care and feeding of power grid tubes on the CPI site
(they own Eimac), http://www.cpii.com/library.cfm/9 .

Gerry....

"Jim" wrote in message
...
Gerry;

Thanks for the link. The SB220 had a tap on primary, so when you
switched to CW/RTTY you did not have to retune the amp,
which was probably done by others.

I'll check out the site.

Jim



As a note, for information...

The SB-20 was designed to meet the old FCC regulations which
dictated power input, not RF output.

73, Pete