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
_______________________________________________
Amps mailing list
Amps@contesting.com
http://lists.contesting.com/mailman/listinfo/amps
|