[Amps] SB-220 Project.

[Joe]

I want to Thank EVERYONE who helped me bring this old SB-220 back from 
the Grave.

It so far is working beyond my expectations. So much so that I am 
actually somewhat scared of what other part may not handle the new 
capabilities. Someone made the analogy of installing a 454 V8 into a 
Ford pinto. And yeah... Good comparison.

Watching Grid current on key down, the highest it gets is about 180 ma. 
so way safe below the 240/250 limit true?

Yet I really do not know what it truly is putting out. My WATT meter was 
not too long ago calibrated against a Bird so I know it is close. Yet, 
with my TS-430S at 100 watts drive, it is pinning the needle on the watt 
meter full scale is 2KW. so it's making more than 2 KW.

Changes from "Stock" that were made are:

Harbach soft start,  Nice,,

Home brew HV cap and resistor section.

AnTeck Toroidal HV Transformer.  EXTREMELY Happy with so far. 1/3RD TO 
1/4 THE PRICE of other replacements.

Changed the LOW/HIGH voltage switch into a Standby/Operate switch

Harbach RM meter HV Board,  Also Nice,
But not using the Bias section. With the New much higher HV Voltage the 
idle current with a stock Harbach Board was way HIGH like 250 ma. The 
tubes were turning orange doing nothing but idleing making no output 
power. I tried as Harbach said to add more diodes to the string to knock 
it down more and I did,  I added 10 more, and that knocked it down to 
about 180 ma. Better but still gets hot with not very long transmissions.

I loved the old home brew active bias that this amp had but got toasted, 
so hunted down a new one and someone suggested from Ameritron, their,......

EBS-1H Electronic Bias Board.
Works AWESOME!!!!!! In idle with no drive idle current is ZERO, 
slightest drive at all and you have bias and it's fully adjustable. I 
set it to where many said I should at about 150 ma.

The amp now in SSB the plates even at that 2KW+ out never change color 
at all,
In CW at same output it takes a LONG CQ of say 30 seconds or so to start 
to get them to a dull RED.

ONLY with dead key down solid carrier can I get them to orange point and 
that is still like at 30 seconds or so. but they cool off very quickly.

so, so far very happy,

And again a GIANT Thanks to everyone here on list and many that helped 
me off list also.

THANKS!!!

Joe WB9SBD