The AM Forum

Well. Sometimes one is directed where to go by an unseen hand. I start rapping about 4E27's and 4 of them show up on ebay.

10 bucks a tube. so these puppies will be my finals, 2 and 2 spares, and I'll mod the snot out of them with 811A's.  8)

Pretty happy. now just gotta find another plate xformer and a bunch of other junk. Like a mod transformer.  :-X

I've seen that happen over and over.  Somebody here -- or on a reflector somewhere -- starts talking about something, a part, a radio they want, and lo and behold it shows up on eBay minutes later.

I have a feeling it's less about providence or dumb luck, and more about guys with warehouses of stuff monitoring and sensing an opportunity .. :-)

Grant/NQ5T

Good luck with them. I've never seen a Gammatron that worked. They, at least the 250TH types were always gassy and that was true of their 100TH tubes as well. I have some other type Gammatron types that I haven't tested yet so I don't know about them. I wonder if anyone else has any experience with Gammatron?

Your money would be better spent with Eimac 4E27/125tube. In the case of Eimac, I have never had any that were gassy. Some became gassy after a few years of service. When they did turn gassy it was like one day it  was fine and the very next morning, it was gone.

If they turn out to be gassy, let me know as I have some of the Eimac types both used and NOS. I'm sure we can make a deal.

Terry

well, if they're gassy I'll know. for 10.6666 bucks a tube I'll take the chance on em.  ;D And yeah, I'll check out ur stash.

As I understand it this thread is about Gammatrons. But Terry is discussing the 250-TH and 100-TH, which are Eimac.

Gammatrons were built by Heintz-Kaufman, not Eimac. In 1937 I had an AM rig that had two HK-354's in the final. Those tubes were built by Heintz-Kaufman, not Eimac. Those tubes were not gassy, in fact I used them for several years. My Dad, W8YNG, used the same rig after WW2 with the same HK-354's until he upgraded to a pair of Eimac 450-TH's.

I hope this adds some clarification to the thread.

They did have some look-a-likes to the Eimacs. They looked like them. After all these years I think it's amazing that any 60 year old vacuum holds.

Dr. Robert Goddard, the rocket pioneer from the 1930s, got a patent for a Gammatron tube. I saw an exhibit of this at the Roswell museum 2 months ago.

Next time I'm at the camp I'll take a picture of them. They are not Eimac. But anyhow, all input is welcomed. By yumping Yemminity I'll do that ya hear  ;D ;D

For $5 more you could buy a brand new 810 from China and make a 300W rig as elegant as this.

The rest of the story is at http://schmidling.com/radio.htm

js

Not earth shaking but it turns out H&K did make 250TH's tubes. I have one as shown in the eBay sale. I think the one I have will draw about 500 mills at 50 volts. I also have a 100TH by Lewis & Kaufman that looks good but I could run a car on the gas  ;D
http://cgi.ebay.com/POWER-TUBE-HEINTZ-KAUF-250-TH-Ham-Radio-VT-220-H5_W0QQitemZ220464455601QQcmdZViewItemQQptZLH_DefaultDomain_0?hash=item3354b49fb1&_trksid=p3911.c0.m14 (http://cgi.ebay.com/POWER-TUBE-HEINTZ-KAUF-250-TH-Ham-Radio-VT-220-H5_W0QQitemZ220464455601QQcmdZViewItemQQptZLH_DefaultDomain_0?hash=item3354b49fb1&_trksid=p3911.c0.m14)

I've got 6 brand new HK 257B's now, hope they're not all gassy.  ::)

Me too Derb, those tubes look cute to me and I want to see the red glow they should make. Maybe you could set up a test jig to see what they'll do before you get too committed to use them.   

well, the good news is they use 813 sockets so I could just do the ol switcheroo if they all suck. wouldnt even have to change any voltages except the fil.  :D