866 jr subs? Globe King 400B

[K8WBL]

Finishing up the restoration of my Globe King 400B transmitter and wanted to solid state the 866 juniors in the modulator stage. any suggestions?

73, Tim
K8WBL

[W2PFY]

Perhaps on the eBay and maybe on here you can find solid state direct replacements that just plug right into the socket. If the filament transformer is good, just unhook the primary. You may someday want to sell it or run tubes. I would recommend 866AX tubes or 3B28 tubes if you want to go back to hollow state. If it belonged to me, I would try to find some 866AX Amprex MV tubes

[Pete, WA2CWA]

How about a couple of diodes:

[K8WBL]

Thanks guys, well, I cannot easily use the solid state plug ins...which would be great -  as the 866 JR do not have a plate cap - diodes are what I was going to do but will have to make up my own plug in caps I suppose - thought there might be some for sale, but I cannot find any...all are for either the 866A or smaller tubes like the 5U4 variety....

Tim
K8WBL

[Pete, WA2CWA]

Find an old tube with the same pins, break the glass, and clean out the core. Figure the PIV rating you need, get some diodes, mount them on a perf board (width the same as the inside diameter of the tube base you just cleaned out), wire the diodes to the pins you need and epoxy the board into the inside of the tube base. I've been doing this for many years with the majority of all my tube rectifiers. Sell the tube rectifiers to the audio guys and retire early.

[W2PFY]

Where did you get that information from? The 866jr's have a plate cap.

see link below

http://frank.pocnet.net/sheets/084/8/866Jr.pdf

[Opcom]

Would a plug-in replacement for the 5Z3 work? The 5Z3 is the older kind of 5R4.

The pinout is the same except the 5Z3 has anodes on pins 2 and 3. They are usually rated 2800PIV at 1 amp.

Some 866Jr have a cap, some do not. sheets attached.

The non-cap datasheet attached claims what looks like a 5000PIV rating, but most sheets indicate a 1250VDC output.

Nice picture of one: http://www.r-type.org/exhib/aad0001.htm

and someone's avatar is one. For my part, I love non-capped 866Jr's, and would gladly trade you a pair of solid state 5Z3's (I think I have them here)

- in any case what's your AC input and DC output, so as to judge the PIV necessary?

[W2PFY]

That tube was not ever used in that rig to my knowledge. but then my knowledge is limited. I'll sign out from this thread and let you guys thrash it out.   

[K8WBL]

MIne in the GL400 have rounded tops, no plate caps... all wired under chassis, 4 pins.

I know what your talking about I think, smaller versions of the 866A tubes, but I cannot remember what they are...

TK

Where did you get that information from? The 866jr's have a plate cap.

see link below

http://frank.pocnet.net/sheets/084/8/866Jr.pdf

[k4kyv]

Would a plug-in replacement for the 5Z3 work? The 5Z3 is the older kind of 5R4.

Not exactly.  The 5Z3 is the older kind of 5U4.  It is electrically the same as a 5U4G.  The 5R4 draws 2 amps of filament current, the same as a 5Y3 or 80, but it is  rated for much higher voltage.

The 5Z3 and 5R4 have the same filament voltage and socket connections, but are not electrically equivalent.

[w3jn]

The 866JR is a half wave rectumfrier.  It does NOT have a plate cap.  The basing diagram on the NJ7P tube database website is wrong.

A 4-pin base with 3 or 4 1N4007s or the 1N54xx equivalents in series would work fine.

[K8WBL]

Thanks, the diode string sounds like the best choice,

73, Tim K8WBL

PS> Not too long before my BIG signal comes out from Cincinnati...hi hi  been trying to get this Globe King 400B going for some time now...cleaned up and now getting fired up...

[flintstone mop]

I would try to keep the 866's for that beautiful glow. The 3B28 is not an impressive pube for glowing. There seems to be a lot of flavors to choose from.

Fred

[Todd, KA1KAQ]

Early GKs used the 866Jrs and V70Ds, both of which are harder than snail snot to find these days. Not sure if a 3B28 would drop in, plenty of glow from the ones I have but there are probably other issues.

The fellow who makes Copper Cap SS replacements might have one, or could easily build them for you if you decide to go that route. He offered to build a CC 5Z4 to replace the metal tube flamethrower in my 32V-2 some time back.

[w1vtp]

Finishing up the restoration of my Globe King 400B transmitter and wanted to solid state the 866 juniors in the modulator stage. any suggestions?

73, Tim
K8WBL

Here's an outfit that will make SS versions (Todd already mentioned them).  Yours would be a custom job but they look like they could do it.  They have an email address on their web site

http://www.webervst.com/ccap.html

I have some HB SS 866s at home.  I'll try to take a picture of 'em to show you what I did.  They worked fine

Al VTP

[K8WBL]

OK Al, sounds good.  I have some NOS Russian solid state plug-ins.  Guy said they were for 866 but have no plate caps.  These are open arrangement deals and each use 4 diodes per tube/SS plugin.  So, my question, dumb as it may sound, but dealing with HV I want to be sure...is what pins do these diodes connect to and in what direction?  I should be able to make these work I think...they stand about 5 inches tall.

73, Tim K8WBL

[w1vtp]

I think I have this straight -- the original 866Jr's were a bit derated from the HY866 JRs (the latter being a Hytron product).  You really need to refer to a schematic of the Globe King.  It seems that the connections all on the bottom.  If so the connections (according to my 1950 ARRL handbook) should be pins 1, 4 filament.  The plate for the standard 866JR is pin 2.  The HY866Jr has the plate on the top.  The HY866JR doesn't apply in this case, apparently. 

There is a center tap for the filament xfmr.   I've included a schematic courtesy of

http://bama.sbc.edu/

As you can see the 866JR fil xfmr uses a center tap.  Keep that in mind when going to a SS replacement.  If you keep the fil xfmr in there you will have continuity to the swinging choke but you will have to make one connection to either side of the filament.  It will go through the filament transformer to the swinging choke.  For a positive output supply, as in this case, the anodes go to the windings on the HV xfmr - the cathodes are tied together and go to one of the filament connections.

Here is the photo I promised of my 866 SS replacement.  I wired them so that once I pulled the filament transformer ('cause it was shorting to ground) I had continuity from the output of the SS rectifier to the swinging choke.

'Nuf for now. 

73, Al W1VTP

PS:  I've included a pic of the xmtr I used those SS replacements in.

[K8WBL]

Thanks Al...

Tim

[w1vtp]

Another note.  Those SS rectifiers are no longer available from Solitron.  However, there are rectifiers available at:

K2AW's Silicon Alley
175 Friends Lane
Westbury NY 11590
+1-516-334-7024

I see his ads in QST and his rectifiers are mentioned in several HB HV power supplies.  They seem to be a good product (no personal experience).

Good luck, Al

[flintstone mop]

Don't forget the usual pitfall of changing to solid state rectumfriers. Maybe a little extra B+ might not hurt the modulators.

Fred

[Tim WA1HnyLR]

Ahh yes,
 to solid state or not to solid state,That is the question. The Globe King 500 used a pair of 816s . I would solid state the supply. A rule of thumb I use is for every 100 volts of outpoot 1Kv PIV of diode. I know this sounds like overkill but diodes are cheap enough. Being that the supplies are choke input the transient spikes can kill diodes. Overkill is good.The K2AW type diodes work well. They are easy. Drill the hole and mount them up. Plain old Radio Shack 1KV piv diodes work well. Just get a piece of perf board and make them up. Mount the board underneath the chassis. The modulator power supply is underfiltered. 6MFD is not enough capacitance . By removal of the 866 jr tube sockets and the accompanying fillament transformer there should be plenty of space above on the chassis for a good sized oil condensher. The blue glow of the Mercury vapor rectifiers is nice but there is no peek-A-boo window to observe them . Why bother with the Mercury vapor tubes when you can't see them. In terms of voltage increase. A gasseous rectifier has a voltage drop of 15 volts. 10Kv of solid state 1s 7 volts. Solid stating the power supply will result in an increase of 8 volts! insignificant. good luck
De Tim WA1HnyLR

[K8WBL]

Thanks to all who applied, what happened here is that I have 3 GK400...one is  a B and the other a C.  On the B, it has been hacked into quite a bit on the mod chassis and someone replaced the 866jr with 816, with caps.  I put in soild state versions of the 866A's and they seem to work fine...looks like there was the clipping mod put in and then taken out.  also the Couplates have been removed on the B...the C appears unmolested, except some one removed the HV power supply on the lower deck...for another project...so I am looking for one of those...thought I had one but its too tall...not much room between these decks on the globe kings....

73, Tim K8WBL