8643 Data

[Jim, W5JO]

Wonder if anyone has a data sheet on the 8643?  I have searched all over and can't find it on line nor in any publication I have.

If you have the information and can scan, I would appreciate it.

73  Jim
W5JO

[flintstone mop]

Jim
Are you sure it's not an 8463??? I cannot find an 8643 either.
Stay tuned to the thread.
Fred

[Pete, WA2CWA]

8643 used in the Drake TC-2.

Google found this quick.
From one of the newsgroups:

8643: double tetrode.
Vf=13.5V or 6.7V   If=1A or 2A.
Pa = 2 x 38W max.
Va = 800V max.
Vg2 = 300V max.
mu = 7.

Base: 1-7 = f,f. 5 = heater CT.
2 = g1-1
3 = common g2
topcap1 = a1
4 = common cathode
6 = g1-2
topcap2 = a2

Source: GE essential characteristics 1973

[w3jn]

I think I have one or more of them, Jim, you need one?

[Jim, W5JO]

I think I have one or more of them, Jim, you need one?

Interesting about the Drake rig.  They were used in the Motrac series radios on UHF and the radio put out 100 watts or so.

Yes I do need one.  "What is your price"?   

73  Jim
W5JO

[Jim, W5JO]

By the way thanks Pete.  I looked high and low for that information but did not find it on the I net.  Did not know Drake used it.

73  Jim

[Pete, WA2CWA]

Actually I'm surprised that a number of tube vendors still sell this tube. The picture came from one of three(I think) vendors on ebay selling them. I think I also have several of these floating around here somewhere.

Years ago I had mentioned in some on the air conversation that I acquired a Drake TR-6/VFO/SC-2/TC-2 combo. Someone then broke in and indicated I would probably need spare finals for the TC-2 so we worked a deal. The follwing yea,r took the entire package to Dayton and found it a new home. The spare tubes weren't part of the package. So they're probably still here somewhere.

[WA1GFZ]

motorola used to rape customers for about $200 for that tube.
did about 100 watts but never saw one used at hf.

[Ian VK3KRI]

8643 used in the Drake TC-2.

Looks very similar to a Phillips 6/40 tube. They were used here alot in VHF base stations.
                                                             Ian VK3KRI

[The Slab Bacon]

The 8643 is basically a souped up version of a 5894 with a little higher dissapation rating and a little more emission. They were primarily used in Motorola 110w VHF and 
65w UHF Motrac mobile radios and their associated base stations.

The motorola versions had plain steel pins while the Amperex versions had gold plated pins. The pinout os the same as a 5894 but the plate pins are thicker on the 8643.
The motorola part has a long Motorola part numba and a plain brown box.

If you need them the tube vendors usuallly want big bux for them but you can still find the motorola versions fairly cheap at hamfests as there is not much call for them anymore.

I would love to see someone build a nice HF rig using them as they are quite a strapping little tube.
                                              The Slab Bacon

[W3SLK]

They almost look like a slim version of the 829B which has also been used at VHF. I don't know what the differences are between it and the 829B but I always see the 829B's going for a song.

[w3jn]

I think I have one or more of them, Jim, you need one?

Interesting about the Drake rig.  They were used in the Motrac series radios on UHF and the radio put out 100 watts or so.

Yes I do need one.  "What is your price"?   

73  Jim
W5JO

Absolutely free.  It's a karma thing

Now lemme look thru the stash and see if I got one for sure...

[Jim, W5JO]

I would love to see someone build a nice HF rig using them as they are quite a strapping little tube.
                                              The Slab Bacon

I, today, acquired a Globe Champion 300A, sans the AX 9909s, but with two pair 5894s.  I am going to convert it and when done put in the 8643s if I can get a pair.  JN has be gracious enough to look and some other people are looking, which is why I gravitate to this list.  There isn't a nicer bunch anywhere.  Needless to say, anyone who posts wants here, I look to return the favor.

As a former Motorola Service Station owner, I cringed the times I had to replace one of these tubes under contract.  It was very seldom compaired to the 5894 in the VHF stations, but at the price Motorola charged for the 97-136-02 (the 5894 was the 97-136-A01), it was enough for me to cut small donut holes in my desk chair.

If you are intersted, the Chump is in fair to good condition.  The electrolytics need changing, resistances checked, the finals modified, and some surface rust removed from the transformers and it will be ready for the warm up period.  It won't be the queen but will look good enough to sit adjacent to the GK 500A.

I am checking my tube stock, the guy (the only nice one in my neighborhood) gave me a pair of 809s, a couple of 2E26s, and I am in process of checking them on my WE tube tester.  The real test will come when I apply filament and HV to the thing.  I plan to paiir it with a NC 183D on a desk top combo and see how much I can get out of the thing.  I am looking for 150-175 watts and the famous Globe audio.  I wonder if it will have the minor hum the GK 500 series has.

My wife is gone for about 7-9 days and maybe when she returns, I will have enough done that I can finish in a reasonable amount of time.

73  Jim
W5JO

[W3SLK]

Jim said:

today, acquired a Globe Champion 300A, sans the AX 9909s, but with two pair 5894s

Jim what ever you do, don't turn your back on the thing when the filaments are on. I have one that I turned everything on and made a short trip into town, (about 3 miles). About half way there, my fire pager goes off for fire call at my house! To make a long story short, The LVPS T-1, shorted out and cooked all the tar out and smoked the basement and the shack. Unless I find one locally, it looks as if PW Dahl is going to get my business. This transformer not only has the LVPS but also the filaments for the rectifiers and its going to be a pain in the groin replacing the dang thing.

[Jim, W5JO]

I remember you telling the story, but did not remember it was a Champion.  I do not leave the filaments on a transmitter when I am out of the shack for any time, thanks for the tip.  I wonder what caused the short.  I plan to put SS plug in rectifiers in the HV and probably in the LHV supply.

Have you considered Gary Brown, WZ1M up in Maine for a rewind?  It is a bit less expensive than PWD and he does quality work.  I have never asked about potted transformers but I would ask before you spring for Dahl.

For the better part of it's life, it has been in climate controlled rooms, so there is little in the way of corrision and only surface rust on the other transformer laminations.  So far resistance checks show everything in the green, but I haven't gotten to that transformer yet.  Resistance is one thing, but HV is another with current.

Work in progress, thanks for the reminder.

73  Jim
W5JO

[Ian VK3KRI]

They almost look like a slim version of the 829B which has also been used at VHF. I don't know what the differences are between it and the 829B but I always see the 829B's going for a song.

The 829s don't have internal cross neutralisation which  the others do, also the 829 is phyically two tetrodes in the same envelope, the other types have a single cathode with an anode on each side of it.   Maybe an 829 would be a good choice for a compact modulator ? 

[WU2D]

Yeah the Motrac mobiles and the base stations and some repeaters used em too. Good profit for the Moto radio shop since the cops were too cheap to change out Motracs after pulling them in and out of 20 squad cars. If they don't get 25 years out of a radio, it is considered junk. We made a lot of dough on installs and changing out tubes when I worked in a small shop in the early 1980's.

The 829B is a great tube, but they do take a lot of grid drive. I souped up a WW2 SCR-522 with an 829B in the final instead of the 832. I had to lower the socket with spacers, but it worked great. I went from about 8 Watts out to a strapping 22 Watts with the 829B.

I have used the tube single ended too, with both sections in parallel; at least in a HB 10 Meter rig with another one as the modulator - worked fine with a surplus TCS transformer.

I heard you can get 40-50 Watts out on 6M with a single 829B in push pull.

Steve WA1HUD apparently had some trouble with the 829B tube on 220 MHz and said that the 5894 is a proper VHF/UHF tube and to throw the 829B's away. I don't agree, I think the 829B is classic and rugged and well worth playing with, even now.

Mike WU2D

[W3SLK]

Jim said:

Have you considered Gary Brown, WZ1M up in Maine for a rewind?  It is a bit less expensive than PWD and he does quality work.  I have never asked about potted transformers but I would ask before you spring for Dahl.

I had thought about that but I don't recall the price. It would have to be less than 1/2 of what it would cost to get from Dahl.

[Jim, W5JO]

I had thought about that but I don't recall the price. It would have to be less than 1/2 of what it would cost to get from Dahl.

It will probably be 75% of the Dahl price.

[Jim, W5JO]

I have been working on radios for a very long time.  Too long to count right now, but I found something in the Globe Champ 300A that I have never seen before.  It is an open HV bleeder resistor.  I don't know how it happened but is was open.

The resistor was a 100K ( pretty standard for Leo's HV stuff) at 50 Watts.  Given 1000 volts HV, 50 watts is overkill in wattage.  Even mounted where it is, it should have held up under the stress.  It didn't.

Not too long ago on another BB, a discussion took place about shorting sticks.  I would have really needed one for this rig.  The discussion on shorting sticks came to two conclusions.  1. use a direct grounded stick and 2. use one with a high value resistor in series with the ground.  I prefer #2.  Then add a direct ground to prevent the caps from building up a charge following discharge.  But that is just personal preference.

Update, I have the final subchassis converted for 5894/8643, most of the electrolytics replaced.  I have replaced one of the selenium rectifiers and have two to go.  I have all the tubes ready to go in place and have the cabinet to paint.  I will use some polishing compound on the front panel and replace the line cord with a 3 wire.  The fuse holder is broken and will be replaced.

The good news is that I am only throught 1/4th bottle of whiskey and 1/2 pack of cigarettes.