Warning: Creating default object from empty value in /homepages/11/d132647312/htdocs/Amfone/mkportal/include/SMF/smf_out.php on line 47
How about 8 3-500's ?




 
The AM Forum
April 22, 2019, 12:47:09 PM *
Welcome, Guest. Please login or register.

Login with username, password and session length
 
   Home   Help Calendar Links Staff List Gallery Login Register  
Pages: [1]   Go Down
  Print  
Author Topic: How about 8 3-500's ?  (Read 2419 times)
0 Members and 1 Guest are viewing this topic.
KM1H
Contributing
Member
*
Offline Offline

Posts: 3519



« on: March 31, 2013, 12:39:54 PM »

http://www.ebay.com/itm/C98537-Lot-8-Eimac-3-500Z-High-Mu-Power-Triode-RF-Tubes-w-Sockets-Chimneys-/330896766180?pt=US_Ham_Radio_Amplifiers&hash=item4d0afbf4e4#ht_2354wt_913

I have never seen them used that way but price is not bad for local pickup if they are any good. Bring a jig to test at a much reduced voltage.

With 4 at RF and 4 at audio it would do some serious power Grin

Carl
Logged
Opcom
Patrick J. / KD5OEI
Contributing
Member
*
Offline Offline

Posts: 7135



WWW
« Reply #1 on: April 01, 2013, 12:09:51 AM »

How to test those like that?

let's see if I can guess right. Consider it a chance for you guys to educate me on lo-volt testing of HV tubes.

apply fil volts..

1.) and then see how much B+ is needed to make them take full plate current? That's a lot of juice 6KV, not a wall-plug deal. -not best

2.) 1KV and pulse the grid to 27V with 3 nine volt batteries to see if you can get to 400mA plate current? The grid current would be 100mA, maybe OK?

Logged

Radio Candelstein - Flagship Station of the NRK Radio Network.
wa3dsp
Member

Offline Offline

Posts: 289


WWW
« Reply #2 on: April 01, 2013, 02:45:05 AM »

I have no idea about the 3-500, I don't have any but the 811A and 572B can be tested by applying filament voltage and tying the grid and plate together. Apply positive voltage to the plate, negative to the filament transformer CT. A good tube will draw 250ma at about 44 to 45 volts. It would be interesting if someone has a known good 3-500 to run this test and see what you get. Then you can compare other tubes. It is also a good idea to just apply filament voltage for an hour or so on a tube that has been out of service for awhile.
Logged
K5UJ
Contributing
Member
*
Offline Offline

Posts: 2845



WWW
« Reply #3 on: April 01, 2013, 09:46:36 AM »

they have radiation warning labels on the tube chimneys.  weird.

I'd take a pair modulated by two pairs push pull.  I've looked at datasheets for 3-400/3-500 before and it seems that for plate modulated PA, the drive to the grid(s) has to be modulated to some extent to hit 100%.
Logged

"Not taking crap or giving it is a pretty good lifestyle."--Frank
kb3ouk
Member

Offline Offline

Posts: 1576

The Voice of Fulton County


« Reply #4 on: April 01, 2013, 11:06:08 AM »

they have radiation warning labels on the tube chimneys.  weird.

I'd take a pair modulated by two pairs push pull.  I've looked at datasheets for 3-400/3-500 before and it seems that for plate modulated PA, the drive to the grid(s) has to be modulated to some extent to hit 100%.

I've saw that on the tubes themselves but never like that before, I believe they put that on there due to the thoriated tungsten filaments in most transmitting tubes, since thorium is radioactive. And all high mu triodes need a little modulation on the drive to be able to make 100 percent modulation.
Logged

Clarke's Second Law: The only way of discovering the limits of the possible is by venturing a little past them into the impossible
W1RKW
Contributing
Member
*
Offline Offline

Posts: 4125



« Reply #5 on: February 05, 2019, 03:55:04 PM »

If one had several dozen tubes with thoriated filaments and if radioactive is there a danger?  I have a bunch and just learned that thorium is radioactive.  Anyone have any insight on radioactive tubes?  My shack is in the basement and have always wondered about radon exposure. I don't think I have an issue with radon but knowing I've been sitting next to a bunch of potentially "hot" vacuum tubes doesn't sit well with me. 
Logged

Bob
W1RKW
Home of GORT. A buddy of mine named the 813 rig GORT.
His fear was when I turned it on for the first time life on earth would come to a stand still.
n1ps
Contributing
Member
*
Offline Offline

Posts: 281


Zorch!


« Reply #6 on: February 05, 2019, 07:54:01 PM »

geiger counter kits are pretty inexpensive.  I built one with a russian tube.  Fun to play with anyway. 
Peter
Logged
N0WEK
Contributing
Member
*
Offline Offline

Posts: 774



« Reply #7 on: February 05, 2019, 07:57:01 PM »

Least of your worries, unless you want to break the tube, grind up the filaments and snort them.

Coleman lantern mantles used to be coated in thorium.

I suppose you could try running them with enough voltage that they'd kick off X-rays.
Logged

Diesel boats and tube gear forever!
PA0NVD
Member

Offline Offline

Posts: 515


Nico and Chappie (Chappie is the dog...)


« Reply #8 on: February 05, 2019, 08:34:17 PM »

But the energy will be very low, less than 5 - 6  kev only with a HV of that level. , so the radiation is attenuated by about any structure like the glass enveloppe, a chimney, a metal plate etc.
Thorium is an Alpha emitter. You can stop Alpha radiation with a piece of paper
I have a sensitive geiger muller counter, sensitive for high energy Alpha and Beta radiation. There is absolutely no measurable radiation outside a tube with a thoriated filament, so don't worry, even in the presence of many tubes.
Some AN-GRC9 sets are really active due to the radium paint of the lettering. , especially the French made sets can be extremely hot. Take care with those sets, there is some Radon emission!!
I gave one to a specialist and he could remove the paint. He didn't want to destroy the set. . It really was too hot for me, the geiger counter did peg!!
All AN-GRC9 transmitter fequency dials are radio active, but quite low. No problem there.
Logged
WBear2GCR
Member

Online Online

Posts: 3668


Brrrr- it's cold in the shack! Fire up the BIG RIG


WWW
« Reply #9 on: February 06, 2019, 09:19:40 AM »



Post is from 2013??

     
Logged

_-_- bear WB2GCR                   http://www.bearlabs.com
W1RKW
Contributing
Member
*
Offline Offline

Posts: 4125



« Reply #10 on: February 06, 2019, 05:04:32 PM »

yes it is.  Figured I'd search for a post with the search word "radioactive" and up popped this post and responded rather than start a new post.

Thanks for the feed back on the radioactive aspect of thoriated filaments.
Logged

Bob
W1RKW
Home of GORT. A buddy of mine named the 813 rig GORT.
His fear was when I turned it on for the first time life on earth would come to a stand still.
Opcom
Patrick J. / KD5OEI
Contributing
Member
*
Offline Offline

Posts: 7135



WWW
« Reply #11 on: February 06, 2019, 07:56:53 PM »

Feel free to send me all the thoriated tungsten filament tubes that are unwanted. same with mercury rectifiers.

No broken/duds please.
Logged

Radio Candelstein - Flagship Station of the NRK Radio Network.
WBear2GCR
Member

Online Online

Posts: 3668


Brrrr- it's cold in the shack! Fire up the BIG RIG


WWW
« Reply #12 on: February 06, 2019, 08:26:01 PM »

Patrick,

You may not be fully qualified to handle the incoming onslaught... I'm here to help you safely
dispose of these hazardous items! Remember now, these awful and dangerous items MAY cause
cancer in the State of California!

Appropriately qualified you may be able to receive our exclusive FREE SHIPPING BONUS!
Inquire today!


                       _-_- signed, expert thoriated tube disposal experts company
Logged

_-_- bear WB2GCR                   http://www.bearlabs.com
Opcom
Patrick J. / KD5OEI
Contributing
Member
*
Offline Offline

Posts: 7135



WWW
« Reply #13 on: February 08, 2019, 12:05:54 AM »

Bear,

Why not carve up the country between us? I have a fedex acct, we could e-mail call tags to our many happy customers, and make secret agreements on prices later in PHASE II, after the apocalypose when those parts are highly sought by all QRO stakeholders and the EPA isn't around to take notice. We can be the fat cat robber barons of the new electronic renaissance!
Logged

Radio Candelstein - Flagship Station of the NRK Radio Network.
w8khk
Member

Offline Offline

Posts: 842


This ham got his ticket the old fashioned way.


WWW
« Reply #14 on: February 08, 2019, 03:58:29 AM »

Remember now, these awful and dangerous items MAY cause
cancer in the State of California!


I keep hearing this all the time.  I have played with iridescent meters and knobs, mercury, mercury vapour tubes, thoriated tungston filaments, held solder in my mouth as a third hand, and my dad even used his 304TL transmitter as a self-operated diathermy machine Back in the early fifties, and relieved his arthritis.  He lived a healthy life to the age of 93!

But all this good stuff may cause cancer ONLY IN THE STATE OF CALIFORNIA?Huh  what is it about California that makes these harmless items dangerous?  I am so glad I live far from that dangerous state!
Logged

Rick / W8KHK  ex WB2HKX, WB4GNR
K1JJ
Contributing
Member
*
Offline Offline

Posts: 7811


"Let's go sailing, Tommy!" - Yaz


« Reply #15 on: February 08, 2019, 11:57:55 AM »

I keep hearing this all the time.  I have played with iridescent meters and knobs, mercury, mercury vapour tubes, thoriated tungston filaments, held solder in my mouth as a third hand, and my dad even used his 304TL transmitter as a self-operated diathermy machine Back in the early fifties, and relieved his arthritis.  He lived a healthy life to the age of 93!


How true.

Back in the 1990's there was ham scare talk about unshielded homebrew HF rigs and close-by HF antennas causing cancer. There were published maximum radiation levels. At the time I was a member of the AWA and received their quarterly letter. I noticed during the mid-1990's there was a cluster of the old timers dying off. These were the Hiram and Lee Deforest types of the world, hams and broadcasters, who had lived thru the early 1900's, 20's, 30's. These were the "unshielded HF radio days" if there were any - antenna tuners, open wire, exposed finals, etc.

I noticed that most of these radio OTs were living into their 90s, some later 90s, just as your father had Rick. To me that was proof that HF radiation, at least in the one KW level, was not harmful to health.  If these OTs lived that long, even with ancient medical care, then it was good enough for me.

Since 2010 I have stopped using open-viewed Plexiglas and have all big rigs in steel 19" cabinets, (just for aesthetics and safety) but would not have any worries if still exposed.

Of course, high power X-ray and microwave doses are a different thang... but just wanted to make this HF point.

This is not a scientific test, but living to our mid 90's is about 20 years past an average USA man's longevity of 76.  Who knows - maybe RF kills the bad bugs in our bodies...  Grin
There's probably 100 major ways to trigger cancer cell growth, but I don't believe HF is one of them.

T
Logged

K1JJ slogan: “It takes as much time and effort (or longer) to properly test, modify, optimize & fine tune a homebrew AM BIG RIG as it took to initially build it;
plus the skill to tailor the audio processing & EQing to best highlight our unique voices!"
PA0NVD
Member

Offline Offline

Posts: 515


Nico and Chappie (Chappie is the dog...)


« Reply #16 on: February 08, 2019, 01:09:39 PM »

you are right Tom I was involved in Spain and in the Netherlands in RF dangers. I worked my whole life with very high RF fields, up to the level were it heats your arm pointing at an RF device. 50 kW at 27 MHz.
I remember that there were people very worried and claiming to be sick of radiation in a small village were antennas of radio Netherlands at the shortwave were located. They claimed that these antennas should be dismantled. So they were cut down. And all complaints were over, nobody was sick anymore. The strange thing was, that these antennas were already disconnected for more than 5 years... Grin
I had the same experience in Spain, were a group of people were sick, headache etc underneath a new mast of cellular telephone transmitters. So I came over to measure the field strength. People indeed were sick, pale, could not sleep etc. I did measure no excess and explained the screen of the spectrum analyser, and asked if they had cellular telephones, they did. And they never were sick until the mast was placed there. So I had them put the cellular near the antenna of the analyser and explained that that signal was about 10,000 times higher than the mast signal, so whats happening here?. The didn't understand and came with lots of articles about the danger of radiation. I told them that is completely normal that one becomes sick worrying day and night, not sleeping, afraid to get cancer etc, I convinced them that there was NO danger with the proof that there cellular with 10,000 times more signal NEVER gave problems. I called these people a month later and nobody was sick anymore....
All those idiots that love to see there name in the internet and news paper writing articles how dangerous is RF radiation and not even know what it really is., should be stopped worrying people. And when their arm hurts of writing articles, they go to a specialist for an RF diathermy treatment playing dummy load in between a few electrodes with 500 Watts of RF power applied....
Logged
KD6VXI
Contributing
Member
*
Offline Offline

Posts: 1985


Making AM GREAT Again!


« Reply #17 on: February 08, 2019, 03:19:32 PM »

Some people here know the rf levels I've played with.  And I'm not big, by any means.

None of the 11 meter amp builders, mobile especially, that I know or knew have died from cancer.  At least not directly attributable to rf.  One alternator guy died of lung cancer, but that probably had to do with the packs (two) of cigarettes he smoked a day.

Hams, for the most part, have little to worry about at hf.


Now, I WILL pass along this anectodal evidence.

I do know of a ham who had a competition Cb mobile he was building. 16 2879s, probably good for 4.5 to 5kw key down all in.

EVERY time he keyed his station, he went blind.  Not darkness, but bright white he said. It was temp to be sure.  But, after 4 or 5 times, he sold everything and went to ham radio.  He's now a prominent contester!   So I do know of one case of hf radiation causing non perm damage.

I'm more scared of hv myself!  🤣💥

--Shane
KD6VXI
Logged
PA0NVD
Member

Offline Offline

Posts: 515


Nico and Chappie (Chappie is the dog...)


« Reply #18 on: February 08, 2019, 03:43:02 PM »

So am I. My elmer at HV told me that you have to learn working with HV from an OLD technician. Bad HV technicians never grow old......
Logged
Steve - K4HX
Administrator
Member

Offline Offline

Posts: 2490



« Reply #19 on: February 10, 2019, 11:38:41 AM »

Ionizing versus non-ionizing radiation. Supposedly, US hams are supposed to meet radiation exposure limits. Link to easy calculator below. At HF, you have to be VERY near the antenna at high power to exceed the limit. For example, with a kW into a dipole, a licensed amateur radio operator can be as close as 2.5 feet and their family, neighbors, etc can be as close as 5.5 feet.

http://hintlink.com/power_density.htm
Logged
KK4YY
Member

Offline Offline

Posts: 196


Gol’ na vydumku khitra


« Reply #20 on: February 10, 2019, 04:57:57 PM »

If you stand close enough, and long enough, to your antenna on a nice Summer day you could get cancer! Shocked

Seeing your skin turn red is the first clue. You should definitely move away from your antenna...

...and into the shade. Grin
Logged

Fate does not protect its worshipers any more than its deniers.
Pages: [1]   Go Up
  Print  
 
Jump to:  

AMfone - Dedicated to Amplitude Modulation on the Amateur Radio Bands
 AMfone © 2001-2015
Powered by SMF 1.1.21 | SMF © 2015, Simple Machines
Page created in 0.088 seconds with 18 queries.