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[VR2AX]

It was only when I put the power supply for my L-4 on the bench to do some updates, that I realized how many differences there were between the PS-4 and the PS-4B supplies. After comparing the schematics for the two L-4 and L-4B, and checking against my own supply (which I now believe is a PS-4B), I found the following differences.

Can anyone spot any more differences between the two?

1. Each diode string in the PS-4 has only 6 diodes (7 in the 4B).

2. The two large bias resistors in the PS-4 are each 200K 50W wired in parallel (the 4B has two 50Ks wired in series).

3. The 0.82 ohm 'fast burn' fuse resistor is wired in the -VE side of the HT line in the PS-4 (+VE line in the 4B).

VR2AX

This is what I posted some years ago. 50 hz in UK and Hong Kong was not a big issue. My first brand new L4B in UK had a slight HV transformer buzz, which Drake put down to the lower cycle, but said not to worry.

[VE7RF]

It was only when I put the power supply for my L-4 on the bench to do some updates, that I realized how many differences there were between the PS-4 and the PS-4B supplies. After comparing the schematics for the two L-4 and L-4B, and checking against my own supply (which I now believe is a PS-4B), I found the following differences.

Can anyone spot any more differences between the two?

1. Each diode string in the PS-4 has only 6 diodes (7 in the 4B).

2. The two large bias resistors in the PS-4 are each 200K 50W wired in parallel (the 4B has two 50Ks wired in series).

3. The 0.82 ohm 'fast burn' fuse resistor is wired in the -VE side of the HT line in the PS-4 (+VE line in the 4B).

VR2AX

This is what I posted some years ago. 50 hz in UK and Hong Kong was not a big issue. My first brand new L4B in UK had a slight HV transformer buzz, which Drake put down to the lower cycle, but said not to worry.

The L4PS has 7 x diodes per string, BUT they are only 600 v  piv rated.  I bought 8 x new harbach boards....and they too use 7 x diodes per string.  I put 7 x PM600's in each string.   2 x boards per PS. ( one at each end).... bit only one board gets the diodes.   Both boards eacg got 8 x 330 uf caps  + mating 100K @ 3watt eq reistors.

One of my oem diodes ( 600 v piv) finally gave out since bought new back in 1977 (L4B + L$PS bought in 1977).  1/2 the side was blown out..and was spitting arcs / flames.   Replaced the one diode, and all was well..... till last year, when I did a complete rebuild on all 4 x amps.   Bought a caseload of 100 x 330 uf caps..and used 64 of em.  16 per amp.   So far, so good.

Putting the .82 ohm hv ...'fuse' in the B- line is pure fubar.  You can put a 3agc style fuse in series with the B-...like in series with the bias diodes, as long as there is a 100K resistor in parallel with the fuse.  Suck too much cathode current, cathode fuse opens up..and 100k is instantly in the circuit....and amp biased off.

I used a real BUSS  HV fuse + glitch R..in series with the B+.

[VR2AX]

As you say, they are well suited for repairs and upgrades. The ham I sold the amps to, had a swapped out Acom transformer going spare, he had fixed for someone. The HV was good, but the screen secondary had gone. Easy to modify the Harbach and Heathkit Shop boards to work with full wave bridge instead of doubler.

[KD6VXI]

Eimac made glass tubes for several companies in the 60's thru 80's under what was called "Other Labeled" program. Included were RCA, Sylvania and GE. Possibly others. The labelling was done with rubber stamps with logos supplied by the firms ordering the tubes. Warranty was handled by the firms taking delivery of the product.

Like you'd know, Reid


Tongue in cheek, of course.  Thanks for the small history lesson


--Shane
WP2ASS / ex KD6VXI

[W6MTF]

Eimac made glass tubes for several companies in the 60's thru 80's under what was called "Other Labeled" program. Included were RCA, Sylvania and GE. Possibly others. The labelling was done with rubber stamps with logos supplied by the firms ordering the tubes. Warranty was handled by the firms taking delivery of the product.

Like you'd know, Reid


Tongue in cheek, of course.  Thanks for the small history lesson


--Shane
WP2ASS / ex KD6VXI

Yes,  I was there at the right time, just started when Varian >stupidly< sent Eimac technology to the Chinese.
I've written a few pages on that very subject but never published it. I might get around to putting some of that here on the forum.
I'm glad to see a few folks are still interested in tubes.
FWIW I don't hang out on social media (I put this forum in that category, most of it but not all).
I still get a few requests for help with tubes, sources vary sometimes old friends sometimes Eimac  er, CPI, contacts me. I mentioned the next time they need help I was going to invoice them for time spent.

And today an old friend asked me something about Planar Triodes which I have very little experience with but it turned out it was about an application for 1296MHz using tbes intended for Television Translator service, so I'm now looking for info on a Philips YD-1049
and that led me to find this!
An Amperex 3-500Z with the most interesting label on it.
Seller states "the critical internal components are made here in the US, and then the bulbs are assembled in our plant in China using US and European technology and manufacturing processes." 

And with that I recall the way Richardson Electronics convinced Varian management to send three engineers, a new hydrogen furnace and all the test specifications from Eimac to China. It wasn't to build glass tubes but that would come later.

[W6MTF]

when I figure out how to inset an image I'll share that . . . 
Reid  W6MTF

[KD6VXI]

I can't blame you for wanting compensation for your time.  Time isn't free, we only have so much of it, and when you aren't using it for yourself, repeatedly, then it's time for someone to compensate you for it.

Varian wasn't the only idiots that sent their tech to someone else to pilfer it.  Look at what happened with Alpha after using Bulgaria to build an amplifier.  Motorola, Eimac, et al...  All lost their competitive advantage to cheap labor.  And now I hear that Econco may be going the way of the dodo bird from more than one source.  When it becomes cheaper to use communist sourced parts than to have American rebuilt, what's the point.

As to images, you can't upload them here.  You'll have to put them on something like imgur and then put a link in specific http markup to get them to show here.  Glenn is really good about helping people set that up, maybe he can chime in or help you.  You'd think in 2022, Eham would get with the 90s and have image upload...  Then again, it will increase their bandwidth and storage.

But it sucks when you pull up something from the past and the image host has either deleted the file or is long gone out of business.

--Shane
WP2ASS / ex KD6VXI

[W9IQ]

You cannot directly upload images to eHam. Here a way to include pictures in your post.

1.) Open PostImages.org in a new tab or window.
2.) Select the "Choose Images" button.
3.) Select the picture you would like to show on eHam.
4.) Once uploaded, copy the "Direct Link" shown.
5.) In your post on eHam, select the picture icon in the toolbar (lower row, leftmost button)
6.) Paste the direct link of the image you copied earlier. It will be inserted between the IMG tags.

The picture will then render properly when you preview or post your message.

- Glenn W9IQ

[W6MTF]

OK lets see how this turns out,  thanks Glenn!
This is pic of a current Amperex 3-500Z borrowed off a well-known auction website.
I recall Richardson Electronics having rights to the Amperex Brive, France operation so this leads one to wonder where does the U.S. technology come from? Well, Richardson bought the Triton tube biz when they went belly-up. 
Triton had previously bought the glass tube manufacturing from Varian when they ceased making tubes (triodes/tetrodes) at Salt Lake City so its probably full circle. Does this make sense?   

[KD6VXI]

OK lets see how this turns out,  thanks Glenn!
This is pic of a current Amperex 3-500Z borrowed off a well-known auction website.
I recall Richardson Electronics having rights to the Amperex Brive, France operation so this leads one to wonder where does the U.S. technology come from? Well, Richardson bought the Triton tube biz when they went belly-up. 
Triton had previously bought the glass tube manufacturing from Varian when they ceased making tubes (triodes/tetrodes) at Salt Lake City so its probably full circle. Does this make sense?   

I recall that Richardson bought some of the small glass envelope tube manufacturing lines as well.

Somewhat like a well known shop for rf parts and things like that whom tried to get a Motorola device cloned in Japan and it didn't work too well.  But, it did get us the 2SC2879, a failed 28 volt device that the CBers exploited as a 21 to 24 volt device in their 'shootout' vehicles.

It's always full circle with places like that.  In the end, they eat their own.

--Shane
WP2ASS / ex KD6VXI

[KB2WIG]

I would like to know who manufactured my IBM 6146 ? ?

KLC

[KD0REQ]

ha, that's for stuporcomputers

[W6MTF]

Did Sylvania make 3-500Z tubes or are they rebranded? Thanks Mike

Mike, your tube was definitely made by Eimac. I took the liberty of borrowing your great photo to show what we are talking about on the thread before it morphed a bit.
 

[W6MTF]

to better examine the base of the tube for illustrating changes Eimac made to manufacturing over the years I am now the proud owner of subject tube!  W6MTF

[WB8PFZ]

Enjoy the tube. Hope it makes it in good condition. Sold one Eimac to a local. Mike