I own a Heathkit SB-1000. Have not had it to long, just a few months. Had a few issues and just wanted to share them and what I did to fix them.?

one day on 80M I think I hit a bad something. Bad tune or wrong ant, I’m not sure but had an arc or something. After that, 80 was not tuning up at all. 40M and up worked fine but ones in a while, I could swear I seen and even Hurd an arc. I thought it was the tube, but it was just the reflection off the tube that is visible through the right side cabinet. This started happening more and especially while tuning up. And the breaker kicked off the amp and it went back on.?

I took the cabinet off and had a good view at the area that I suspected was arcing and I noticed the wire from the wound core L9 to the band select was broken. There was a small gap between the wire and the chassis about 1/8 or less and I seen it arc across.?

Also, turn 11 on the 80M/160m tank L8 was tarnished black and the plastic form/turn spacers were melted to the point that the shape collapsed into two pieces, pushing into each other with some of the turns, touching each other. ?

Also, the 2.5mH RF choke fried. It lost value but was not open. This agile junctions with the lead to L9 wound core wire that broke.?

I replaced the RF choke, fixed the wire, pulled the L8 tank out, cleaned with toothpaste, water mix, rinsed with water, then rinsed with 91% alcohol, Fabricated plexiglass, spacers and reformed the tank.?
I also used strips of paper soaked with DeoxIT to clean the relay contacts, a trick I learned from my friend Paul. I tested all of the diodes on the rectifier board, inspected everything, tightened all bolts, including the loose ones that hold the tube socket, they also ground the grids. I did the washer mod on the band select junction that runs to the door knob, capacitor on the plate capacitor to prevent corona. I cut many long leads at many junctions from the original builder. and I cleaned everything.?

now she is working great, here is some of the data I recorded after tune up on several bands.?

160M

68W drive = 600W out

Ig = 150mA

Ip = 380mA

Vp = 2900

Zp = 7632

input = 1,102W

efficiency = 54.45%

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80M?

62W drive = 800W out

Ig = 150mA

Ip = 425mA

Vp = 2900

Zp = 6824

Input = 1,232.5W?

efficiency = 65%

40m

63W drive = 810W out

Ig = 150mA

Ip = 400mA

Vp = 2910

Zp = 7275
input = 1,164W

efficiency = 69.6%

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20M and 15M Efficiency about 63%

10M?

58W drive = 700W out

Ig = 150mA

Ip = 435mA

Vp = 2900

Zp = 6667

input = 1,261.5W

efficiency = 55.5%

I have ran about 10 hours or so since I repaired the amp and I’m pretty happy. I do not run the limits in the manual, the manual max limits are:

Ig = 200mA

Ip = 550mA

Output power = 1KW

thats nuts and contradicts Eimac data sheet for a 3-500Z

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Eimac Data sheet max at typical operation at 3KV

Ig = 108mA

Ip = 400mA

output 740W

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Heathkit manual max limits = 37.5% over Eimac max specs and has you exceeding grid dissipation by 50%. Grid is the most fragile part of the tube.?
Eimac states driving impedance is 115.?
grid dissipation = peak voltage X grid current.?
so at 100W drive, peak grid voltage is 150V

150V X 0.2Ig = 30W grid dissipation. ?30W grid dissipation is 50% over Eimac 20W Grid Dissipation.?

I do runs a little over on SSB, about 150mA of Ig and 400mA of Ip, but on CW I run a max of 100mA of Ig and/or 400mA of Ip, no more.?

well, thanks to my friend Paul for his great mind and others!!!

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thanks for reading. Hope this helps someone out there.?
KG2RG