[RTTY] Heathkit SB-1000 On RTTY

[Bill, W6WRT]

ORIGINAL MESSAGE: 
On Tue, 25 Sep 2012 10:01:00 -0400, W4TV wrote:

>I'd suggest the "carrier conditions" rating is the most appropriate for
>RTTY.  With 275-280 mA at 2500V in AB2 one is still looking at a safe
>limit of about 400W from a single 3-500.

REPLY: 
I disagree. The "carrier conditions" you quote are for Class C plate modulated
operation. This is not how the SB-1000 operates. 

Referring to the Eimac data sheet, a more appropriate mode for RTTY is Class B
grounded grid, single tone conditions. Under those conditions the rated PEP
output is 750 watts per tube. Remember - under single tone conditions, PEP and
continuous carrier (i.e. RTTY) are the same. 

A purist will point out there is an error in the Eimac data sheet. What it calls
"Class B" is really Class AB2, since there is significant anode idle current
with zero drive. True Class B would have essentially zero idling anode current
with zero drive. 

I'll repeat what I said in my original post: The limiting factor in the SB-1000
is the power transformer, not the tube or tank circuit. If you limit the SB-1000
to about 600 watts RF out on RTTY, you can run it all day long with no problem.
I ran mine that way for years. 

73, Bill W6WRT