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Title: 4cx1500b tube socket Post by: w4bfs on October 04, 2014, 10:48:56 AM well if I can find a sk800b socket or be able to modify my existing socket that has the cathode grounded to unground it ....has anyone done this ? .... it looks possible but will have to be done with GREAT care by changing metal spacers in the contact fingers stack with insulating spacers
I found out from W5CBS that the infamous Orr super cathode drive ckt is a good match for 4cx1000a / 4cx1500b tubes and I wanna try it ...73 Title: Re: 4cx1500b tube socket Post by: KD6VXI on October 05, 2014, 04:07:39 PM I can tell you this. I modified my 4cx1000 Eimac socket to house my 3cx1000 tube.
Per KM1H the Chinese sockets are easily modifiable. That's what gave me he idea. Incidentally, I have a 4CX1000 tube surplus :-) Super cathode drive isn't all that clean, as has been found. --Shane KD6VXI Title: Re: 4cx1500b tube socket Post by: w4bfs on October 07, 2014, 04:47:29 PM I can tell you this. I modified my 4cx1000 Eimac socket to house my 3cx1000 tube. Per KM1H the Chinese sockets are easily modifiable. That's what gave me he idea. Incidentally, I have a 4CX1000 tube surplus :-) Super cathode drive isn't all that clean, as has been found. --Shane KD6VXI tell me more, tell me more .... Orr claimed in his 1967 Qst article nearly a full order of magnitude distortion reduction .... what was found ? ... might need to talk with you about ur 4cx1000 surplus ...73 John Title: Re: 4cx1500b tube socket Post by: KD6VXI on October 07, 2014, 05:43:06 PM http://www.w8ji.com/vhf_stability.htm
Search super cathode drive. W8JI doesn't like it. I typically take lot of his info with a grain of salt, but he explains this pretty well. He stops short of calling Bill Orr out, but does refer to the person who came up with it as an Eimac employee as well as radio handbook author. The 4cx1000 is surplus to my needs. Got it first, then found out (after winning it for a hundred buck auction) the 3cx1000 was beefier than the 8877, and is the smallest tube they will rebuild. That solidified it for me :-) --Shane KD6VXI Title: Re: 4cx1500b tube socket Post by: KD6VXI on October 07, 2014, 05:49:12 PM Here's a few pics of the 'new' socket and the tube. The 4cx1000 is 'English Electric Valve Company', with a CV9918 code on it. Sold to me by a .UK ham as working, pulled from a piece of patted out commercial equipment. He has posted here before, I believe. Was hand delivered to me, not a hipper, across the pond.
Title: Re: 4cx1500b tube socket Post by: w4bfs on October 08, 2014, 06:22:32 AM thanks Shane .... I read thru Tom's critique and I understood that his disaffection with super cathode drive was with elevating triode grids above ground ... maybe I missed something or as Paul Simon stated in 'Mrs Robinson' - "a man hears what he wants to hear and disregards the rest"
I am back in contact with W5CBS (who reported good results from a super cathode driven 4cx1000) and am hoping for more dialog ... 73 ...John modified 10/9/14 : not Mrs Robinson but rather The Boxer by Paul Simon ....tnx KLC Title: Re: 4cx1500b tube socket Post by: KD6VXI on October 08, 2014, 09:41:22 PM I think your right. I just did a search of my bookmarks, pasted it.
The method Tom speaketh of is floating the grids on a triode. More fubar bs. Let me know how you make out, I just might have found a use for my tube lol. --Shane KD6VXI Title: Re: 4cx1500b tube socket Post by: WD8BIL on October 10, 2014, 01:18:16 PM Quote Paul Simon stated in 'Mrs Robinson' - "a man hears what he wants to hear and disregards the rest" Actually, it was "The Boxer", whoops, I just read your edit!!! Never mind! Title: Re: 4cx1500b tube socket Post by: w4bfs on October 10, 2014, 06:12:40 PM tnx for the sanity check .... on the 4cx1000a/1500b super cathode drive amp .... looks like a go ... power gain of approx 10 (100W in/ 1KW out) ... stable at 3kV ...I may have a sk800b AMfone - Dedicated to Amplitude Modulation on the Amateur Radio Bands
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