Just found a nice 20A DP switch. Going to parallel the terminals. Should give me 40A rating. Should be plenty for supply.
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Drake L4B
- Thread starter Crusher
- Start date
ordered the soft start, should be here middle of next week. Jeff at harbach is waiting on parts and will ship out when they arrive. Will see him up at the Findlay hamfest on the 11th of next month.
WOW! W8CQ is going to Findlay Hamfest...cool
I was at Findlay last year...nice fest...Hope to be there again...long drive though from my neck of the woods...3 hours plus one way...
Don't know if I'll set-up (like last year) or just get a space and set-up the shade tent and coffee pot.
All the Best
BJ
I was at Findlay last year...nice fest...Hope to be there again...long drive though from my neck of the woods...3 hours plus one way...
Don't know if I'll set-up (like last year) or just get a space and set-up the shade tent and coffee pot.
All the Best
BJ
I was there last year. Picked up some nice air variables and some other parts. Partly going up there, have a 3cx15000a7 up there waiting for me.
Wavrider: I have got that same article stached in my Drake file folder just waiting for another RF deck to come along.
When I got my present unit, I thought if I wanted to sell it later the "stock look" would be easier to sell...but alas when the PS took a dump, I said NO I am updating this old girl and getting rid of all the reasons they die.
Hence all new PS parts except stayed with the original Xformer.
W8CQ/Harbach...suggested to do this...this...etc...I followed his advise to the letter.
Well here I am 14 months later, the old girl has never missed a lic.
I thought about switching out the xformer for a Peter Dahl but the extra output of maybe 500w just did not appeal to me at that time.
She loafs along at 11-1200w with 70w drive and if the need arrises she can go 3-400 more...but whose going to notice! Only me.
I went through that stage of Building/Blowing and repairing for many an amp...Now I just like to make them purr...
I have got a PS waiting in the wings for something...
Humm what can I do with 4200+vdc at 3 amps ?
Only time will tell...
All the Best
BJ
When I got my present unit, I thought if I wanted to sell it later the "stock look" would be easier to sell...but alas when the PS took a dump, I said NO I am updating this old girl and getting rid of all the reasons they die.
Hence all new PS parts except stayed with the original Xformer.
W8CQ/Harbach...suggested to do this...this...etc...I followed his advise to the letter.
Well here I am 14 months later, the old girl has never missed a lic.
I thought about switching out the xformer for a Peter Dahl but the extra output of maybe 500w just did not appeal to me at that time.
She loafs along at 11-1200w with 70w drive and if the need arrises she can go 3-400 more...but whose going to notice! Only me.
I went through that stage of Building/Blowing and repairing for many an amp...Now I just like to make them purr...
I have got a PS waiting in the wings for something...
Humm what can I do with 4200+vdc at 3 amps ?
Only time will tell...
All the Best
BJ
Friend dragged over that old L4B, looked like it had been sitting for years.
I recapped and new diodes on the PS.
I ran across that mod page and thought ok Let's see what can be done as I did not like the high Plate current at idle.
With the owners permission I went and did the bias mod and a couple of other things to it.
That old L4B does exactly like you said, just purrs along.
So when I built the 4X1 home brew I did basically The same bias set up. Fused everything that I could fuse.
Works great.
4200vdc at 3 amp?
I have the filament tr for a pair of 4X1, I also have another 4-1000a tube and several sockets.
That 4200v at 3 amps would sure tickle a pair of those 4-1000A's especially driving it with the FT-102
Loafing at legal limit is putting it mildly. I could probably light the fluorescent light bulbs in the shack, without turning the light switch on.
I recapped and new diodes on the PS.
I ran across that mod page and thought ok Let's see what can be done as I did not like the high Plate current at idle.
With the owners permission I went and did the bias mod and a couple of other things to it.
That old L4B does exactly like you said, just purrs along.
So when I built the 4X1 home brew I did basically The same bias set up. Fused everything that I could fuse.
Works great.
4200vdc at 3 amp?
I have the filament tr for a pair of 4X1, I also have another 4-1000a tube and several sockets.
That 4200v at 3 amps would sure tickle a pair of those 4-1000A's especially driving it with the FT-102
Loafing at legal limit is putting it mildly. I could probably light the fluorescent light bulbs in the shack, without turning the light switch on.
Very good article, thanks for the link. Definitely some good info for sure. Going to go thru it a little better when it aint so early.
Switch arrived and I installed today. Just took some 1/4" brass stock and ran across left to right side. Should be good for 40A now. Wired up to terminal strip and mounted to PS case. Looks good. Waiting for soft start and will install before I even test it to see if there are any further problems.
Yes, they are nice amplifiers, Had 3 of them pass this way in last 2 months, mainly changing transformers and replacing HV cap/diode board. But this last one has had more than its share of problems on the HV side. Guess that's what happens when you go back behind someone else's work.
Finally installed soft start last night, jeff forgot to send me the pins for the plug. So called him last night. He's suppose to be shipping them out. That's all I need, then I can put it back together and see what happens.
Soft start complete, on/off switch installed on PS. Had to remove factory switch and install an on/on hi/lo switch. Fabricated switch plate. old one only worked after rocking it back and forth a few times. amp is good to go, new tubes installed.
