The AM Forum

I lit up my 4-250 last night, and that Filament was bright! 
Are they supposed to look like a lightbulb???

Yes they are, Ed. I can read the manual from the light through the window on the KW-1, runs a pair.

I remember the first time it lit off years ago, I thought the same thing and shut it down fast. Couldn't get to that power switch fast enough, though it was gonna launch. A far cry from the dull red glow of your average receiving tube!  :D

There should be 5.0V RMS at the socket and there should be some tube pin cooling even with just the filament on.

In use I like to reduce the filament to the point that the power just starts to drop and then increase 0.1V. Thats the point of best tube life and you can increase as necessary as it ages. While the tube is rated for a slight overvoltage it does reduce life unnecessarily.

Carl
KM1H

Cool! Yea it was a little scary. I've had that tube for a while and the thought of burning it up made me shiver!

So I think I will Definitely need a viewing window now...

Yeah you maybe felt like you were watching a Jack O' Lantern lighting up.

There's a guy on here that lit up the PLATE of a 450TL white-hot, and the tube held up anyway ! 

The 810 triodes also are a white-hot filament. Fun to watch.

Check this video.

http://www.youtube.com/watch?v=46TLmROTTqk

Nice video.  lotsa cool stuff there.

If you need a lamp use real tubes ;D

Carl
KM1H

those heat dissipating plate caps are uber bad, man.  8)  I got 2 of em bud radio style,  but they need a acid bath to clean em up.

I drilled out 2 HR-3's....but really need HR-5's I think.

If'n I HAD a 4-1000 It'd be more than just a lamp!

Actually I think I'll just go for a 2nd 4-250. Adding a socket and such is easier.

Someday I'll go for 833's I think, they look much more Old Buzzardly.

imo the most buzzardly tube family: the wire leads: 852, 860, etc.

(http://vintageham.com/tubeimages/rca852tube.jpg)

Does anybody Have any of those...wooo. Tubeyalar..

back around 1980 and 8, as ozona bob used to say, someone brought in a old wooden table into amateur radio center in downtown baltimore. Not just any table.

It was a transmitter table. whomever made it used the tabletop surface itself to fasten all the components down on, so the entire tabletop was nothing but standoffs, tuning condensers, coils, tubes and such. it had a shelf below and on that shelf was all the power supplies. this rig was death by electrocution personified.

Ernie put it in his storefront window for a few months. It used either 852's or 860's, cant remember which. Was a high power CW rig, no modulator or any sign of there ever being one. I guessed the date of building to be in the 1928 to 1933 timeframe from the components used.

I had one of those tubes that I got out of some military rig back when I was in high school. We had gone to some surplus military warehouse (my understanding was that many schools were invited) and you could take away whatever they had stored there. Between my physics teacher and, I think 3 other guys, we filled a van in about 1/2 hour. Couldn't convenience the teacher to go back for another load. Finally took the tube to some hamfest and unloaded it.

(http://vintageham.com/tubeimages/rca852tube.jpg)

They are very Old Buzzardly looking.  Too hard to find though.

My avatar is an 860 doing its thing.

When in the Navy I worked on several rigs using an 860 VFO with 1 Kv, driving a 860 IPA and a 861 final. Stable as a rock.

Im still looking for an 861.

Carl
KM1H

Yea, that's part of the problem with the cooler looking tubes and such. You might find one to build that Uber-Buzzardly rig, but should it ever go south, you're rebuilding a rig to use what you can get.  Still, the only reason I'm building a 4-250 based rig is because that's what I had so smoke 'em if you got em.

as I recall, a thoriated tungsten filament is designed to be operated at 2400 degrees ...this is a straw color and not a bright white ... bright white operation will be brief ...73 ...John

OM 7FTO sent me a pair of Hytron HY 40's, 7.5 volt filaments, looks like a carbon plate 811. I got em, so I'm gonna use em. Spending too much time on "what if's" and such. Gotta build, get moving. start drilling and blasting under influence of dope.  :D

I should have had a transmitter made by now. radio season is upon me.

Cant wait for my 304TL modulator!   I will post pics of it lit up!

I had a single 4-1000 amp.  First time I lit it off, I flipped the switch fast.. Super bright.  Looked lovely behind glass.

I would love an old 1500T behind Glass!!!


C

I should have the Derbophone amp done this weekend. It has been a major boondoggle, I have just about completely dissassembled and reassembled it. All that is left to do is rebuild the outpoot sensor circuit and install the koolin fan. I should be test firing it this weekend.
I had had a few things come up unexpectedly and didnt get the time to finish it yet. But, it will be done this weekend!!

Now.......... get up offa yo ass and get that antenner up so you be "wavin yo hand in the breeze"

                                                           The Slab Bacon

cool! I'll run by next door an see when Jeremy the redneck can shoot some antenna lines for me. I also have to get my "junk is stuffed everywhere" problem under control before it gets back. Right now I literally have no place to put it. I have iron and transmitter parts in every nook and cranny. Glo's last day off is this Thursday so that's NG, Friday is NG, & Saturday is out because she has a doggie event planned for all day.

Put it on the air and run the hell out of it and see what kinda reports you get.  :D

P.S. one of those thor plate transformers you got me is a perfect match for these HY40's, so a PS will be started shortly. I am going to get that Stancor P-8033 plate transformer off the floor polished up and moved into the small rack today & tomorrow and screwed down.
The Thermador is for the 4-400's. Voltage is too high for little tiny tubes. 2500 is a good 4-400 fit.

it will be hella nice to have something I can just snap on and talk on while all my grandiose plans are either being proven or disproven as the case may be.  :-\