Warning: Creating default object from empty value in /homepages/11/d132647312/htdocs/Amfone/mkportal/include/SMF/smf_out.php on line 47
Tube of the Week




 
The AM Forum
December 02, 2021, 05:27:48 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 2 [3]   Go Down
  Print  
Author Topic: Tube of the Week  (Read 13126 times)
0 Members and 1 Guest are viewing this topic.
KL7OF
Member

Offline Offline

Posts: 2215



« Reply #50 on: May 29, 2021, 08:21:25 PM »

Nice Dennis...do you have one in your collection?   I like the big spade connections on the base..
Logged
W7TFO
WTF-OVER in 7 land Dennis
Contributing
Member
*
Offline Offline

Posts: 2364


IN A TRIODE NO ONE CAN HEAR YOU SCREEN


WWW
« Reply #51 on: May 29, 2021, 09:30:04 PM »

I count 4 here.  Indeed, unicorns. Wink

Need to get pix.

73DG
Logged

Just pacing the Farady cage...
N5RLR
Extra With A Side Of Fries
Member

Offline Offline

Posts: 352


Supremely Lurking


WWW
« Reply #52 on: May 30, 2021, 11:45:44 PM »

New week, new tube. Let's go the other direction.  Let's go down in size. Wink
 
The Nuvistor.
 
The Nuvistor was a type of vacuum tube announced by RCA in 1959. Most of them were basically thimble-shaped, but somewhat smaller than a thimble, and much smaller than conventional tubes of the day. Their size almost approached the compactness of early discrete transistors. Triodes and a few tetrodes were made. The tube was made entirely of metal with a ceramic base.
 
Nuvistor tetrodes were taller than their triode counterparts. Manufacturing them required special equipment, since there was no intubation to pump gases out of the envelope. Instead, the entire structure was assembled, inserted into its metal envelope, sealed and processed in a large vacuum chamber with simple robotic devices. It has been said that this process made them more expensive than competing glass tubes.
 
Some Nuvistors were designed to be used in military equipment (some say that this was their intended application, with consumer- and experimenter use being a nice bonus -- and cover story). They were used in the Ranger spacecraft of 1961-65, and interestingly by the USSR in their MiG-25 fighter jet, presumably to harden the fighter's avionics against radiation.
 
Nuvistors were among the highest performing small signal-receiving tubes. They featured excellent VHF and UHF performance plus low noise figures, and were widely used throughout the 1960s in television sets, radio- and high-fidelity equipment primarily in RF sections, and oscilloscopes. They competed with the solid state revolution, and along with GE's Compactron, probably held it at bay for a few years. RCA discontinued their use in television tuners for its product line in late 1971. As of this writing I've not found exactly when their production ceased.
 
Radio amateurs also found use for Nuvistors, mainly in VHF/UHF converters. QST published a flurry of articles using them in the early 1960s. RCA Ham Tips, of course, published several Nuvistor projects, such as a 2-Meter transceiver in its Spring 1965 issue.
 
I first learned of them in the late 1970s, when I found a copy of the 1966 ARRL Handbook in my high-school library.  Therein was a construction project for a portable 420-Mc. transceiver using a Nuvistor as superregenerative detector and modulated oscillator. 250 mW plate input at 45 VDC!  Cheesy
 
Types:
 
* 7586 - First one released, medium-mu triode
* 7587 - Sharp-cutoff tetrode
* 8056 - Triode for low plate voltages
* 8058 - Triode, with plate cap & grid on shell, for UHF performance
* 7895 - 7586 with higher mu
* 2CW4 - Same as type 6CW4, but with a 2.1 V / 450 mA heater.
* 6CW4 - High-mu triode, most common one in consumer electronics
* 6DS4 - Remote-cutoff 6CW4
* 6DV4 - Medium-mu, intended as UHF oscillator, shell sometimes gold plated
* 8393 - Medium-mu, 12.6 V filament
* 13CW4 - Same as 6CW4, but with 12.6 V / 230 mA heater


* 2021-05-31 Nuvistor And Box.jpg (164.88 KB, 418x400 - viewed 122 times.)

* 2021-05-31 Nuvistor Components.jpg (233.12 KB, 560x400 - viewed 127 times.)

* 2021-05-31 Nuvistors And Glass Tube.jpg (136.58 KB, 424x400 - viewed 126 times.)
Logged

Michael

* * * * * * * * * *


Licensed Since 1990  Cheesy
Opcom
Patrick J. / KD5OEI
Contributing
Member
*
Offline Offline

Posts: 7923



WWW
« Reply #53 on: June 26, 2021, 11:22:56 AM »

We used to snag the nuvistors out of old color TV sets when they were scrapped. Quite a few older equipments still use them like CEI panoramic receivers and oscilloscopes.
Logged

Radio Candelstein - Flagship Station of the NRK Radio Network.
K9PNP
Member

Offline Offline

Posts: 475



« Reply #54 on: June 30, 2021, 05:38:09 PM »

Have a couple left in stock, I think.  Common in the 6M AM equipment like the Lafayette  HA-460 of the late 60's.  Still available from some of the tube dealers.  IIRC, replaced the 6AK5 and others as receiver RF amplifier.  Low noise, reasonable gain.  Of course, the noise floor was considerably lower then, so equipment noise did make a difference.
Logged

73,  Mitch

Since 1958. There still is nothing like tubes to keep your coffee warm in the shack.

Vulcan Theory of Troubleshooting:  Once you have eliminated the impossible, whatever remains, however improbable, must be the truth.
Opcom
Patrick J. / KD5OEI
Contributing
Member
*
Offline Offline

Posts: 7923



WWW
« Reply #55 on: July 18, 2021, 12:37:52 AM »

How about something that is 77 years old, yet advanced at its time and still powerful for its size?

The week's about up.. but I'd like to highlight the 8025 (8025A, and the 8012 /A having identical curves and ratings)

The 8025 is not common in ham homes, but 'large quantities' are available NOS online for $35 from a large surplus sales vendor so it's overlooked. I bought a box of NOS specimens at an antique radio auction for a song and people don't seem to have any idea what to do with them. It's a nice looking tube!

The 8025 was made by RCA and GE.

It was first used in WWII.
http://www.qrp.gr/technology/linearuhf/High_f.pdf
That might explain the original RCA data having a copyright of 1943, but the datasheet having its release date in 1945.

Plenty of pictures available:
https://www.google.com/search?q="8025"+vacuum+tube&source=lnms&tbm=isch&sa=X
Nice looking, eh?

The 8025A is a small, glass, directly heated 1000V triode with 40 Watt plate, a 6.3V, 1.92A filament, requires bias, and is good for up to 500MHz at full input and reduced input to 600Mhz. The filament center tap is not for connection to ground or to a filament transformer CT, but for an RF bypass scheme to minimize lead inductance.

Its advantages for UHF work are very short and direct grid and plate leads which come out both sides of the envelope.

The 8025/A has 1/4" plate and grid caps and a 'small 4 pin' base, and the 8012/A has grid and plate pins instead of caps, and flying leads for the filament.

It requires forced air cooling for CCS ratings, and is rated for 30W ICAS on the plate with convection cooling. Maximum plate current rating is 80mA according to GE.

Typical AM operation as a class C amp show 22W output at Carrier level.

Data sheets:
1943: https://frank.pocnet.net/sheets/201/8/8025A.pdf  - best info about care and feeding of the tube.
1945: https://frank.pocnet.net/sheets/049/8/8025A.pdf
1945: https://frank.pocnet.net/sheets/049/8/8012A.pdf

It's intended for class C operation and no modulator or linear amp ratings are given.

For those QRP interests and others wanting to play with it at zero bias, the curves show that 400V on the plate results in 22 Watts dissipation. 300V gives 10.5W dissipation.
It could be a good experiment to try as a class AB2 or B amplifier. For its size it seems like an electrically rugged tube.

The thoriated tungsten filament is a plus for that bright glow. I think the plate is tantalum. For forced air cooling, the data sheet only says that air should be directed at the bulb. These are not intended to be supported or stressed by inflexible connectors attached to their plate and grid connections.
Logged

Radio Candelstein - Flagship Station of the NRK Radio Network.
K8DI
Contributing
Member
*
Offline Offline

Posts: 241


« Reply #56 on: July 22, 2021, 02:59:28 PM »

Hello folks!

How about this one:  the 4-400A. A tetrode, 400w plate dissipation, high gain, low drive.



Data sheet:
https://frank.pocnet.net/sheets/088/4/4-400A.pdf

A place it was used:
The RCA BTA-1R1 broadcast transmitter

manual:  https://bama.edebris.com/manuals/rca/bta1r1/
Found in a fun catalog:  https://worldradiohistory.com/Archive-Catalogs/RCA/RCA-Transmitting-1962.pdf

Some other applications:
600m linear: http://w5jgv.com/4-400A_600M_amplifier/
Old magazine article for an amp: https://www.robkalmeijer.nl/techniek/electronica/radiotechniek/hambladen/qst/1961/01/page33/index.html

There are hundreds of posts on here that mention the 4-400a, and I am certain there are more than a few AM'ers talking on the air on them even now.  New tubes are available, but expensive. Used are in the usual places. I just made arrangements to buy several, with the rest of the transmitter included.....more on that elsewhere.

I'd like to hear from some of the big guns here about their favorite large tube.. Anyone?  Bueller?

Ed K8DI


Logged

Ed, K8DI, warming the air with RF, and working on lighting the shack with thoriated tungsten and mercury vapor...
N5RLR
Extra With A Side Of Fries
Member

Offline Offline

Posts: 352


Supremely Lurking


WWW
« Reply #57 on: July 22, 2021, 09:16:15 PM »


Now there's a Wish Book!  Grin
Logged

Michael

* * * * * * * * * *


Licensed Since 1990  Cheesy
Detroit47
Member

Offline Offline

Posts: 584


N8QPC on your AM dial


« Reply #58 on: July 27, 2021, 12:10:15 PM »

i'm surprised no one had anything to say about the 4-400. Or it's predecessor the 4-250 which makes appearances in the famous KW-1. Not to forget the 4-125 in the 30K-1. The Johnson product line makes full use of 4-250 in the Thunderbolt, 500 and, Desk KW. I believe that most of these rigs went to the 4-400 in later production. There is another giant in the glass family of Tetrode's the 4-1000.  The 4-1000 is truly in a class by itself. The tube just loves Hi voltage 6000 make them smile. It's to bad they are getting expensive 100 bucks used to get you a good tube those days are all gone. I know there is a lot of fellows  on this board that have built plate modulated rigs with these. Not to mention there uses as a linear amplifier tube. Show us some pictures of your 4x1 rigs don't hide those big legged girls.

Johnathan N8QPC
Logged

"We are all born ignorant, but one must work hard to remain stupid."  Benjamin Franklin
K1JJ
Contributing
Member
*
Offline Offline

Posts: 8541


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


« Reply #59 on: July 28, 2021, 12:19:27 PM »

There is another giant in the glass family of Tetrode's the 4-1000.  The 4-1000 is truly in a class by itself. The tube just loves Hi voltage 6000 make them smile. It's to bad they are getting expensive 100 bucks used to get you a good tube those days are all gone. I know there is a lot of fellows  on this board that have built plate modulated rigs with these. Not to mention there uses as a linear amplifier tube. Show us some pictures of your 4x1 rigs don't hide those big legged girls.

Johnathan N8QPC


ahhhh..... 4-1000As.  That's my choice for  "Tube of the Week."

Here's Fabio II  -  a working 4-1000A plate modulated construction project.  (125K hits on this BB)     A class C pair plate modulated by a pair.     I also run a pair in grid driven linear. (Rico Suave II)     4X1s get my vote as the coolest and most strapping glass tube for ham radio use.   (Followed by the 813)

http://amfone.net/Amforum/index.php?topic=33816.0


And then came "Quadzilla" .... quad 4X1s in linear service:
http://amfone.net/Amforum/index.php?topic=18616.0

4-1000A data sheet:
http://www.tubecollectors.org/eimac/archives/41000a(52).pdf


The beginning of Fabio II -   and Quadzilla linear running... #3 tube was soft when this picture was taken:


* FABIO II .....JPG (325.5 KB, 960x1280 - viewed 103 times.)

* Quadzilla.jpg (324.31 KB, 1280x960 - viewed 105 times.)
Logged

Use an "AM Courtesy Filter" to limit transmit audio bandwidth  +-4.5 KHz, +-6.0 KHz or +-8.0 KHz when needed. 

Nothing like a new homebrew rig. Come into the shack, flip on the switches and everything works perfectly.

And, nothing like an old dog.
K1JJ
Contributing
Member
*
Offline Offline

Posts: 8541


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


« Reply #60 on: July 28, 2021, 12:46:19 PM »

Here's some info on operating 4X1s in linear service, GG included:

http://amfone.net/Amforum/index.php?topic=32823.0



This is a rare notice from Eimac concerning GG 4-1000A linear service:

http://amfone.net/Amforum/index.php?topic=18634.0



There is more 4X1 construction info on this BB by doing a 4-1000A search.


Testimonial: In 50 years time, I've bought both new and used 4-1000As;  always ran air chimneys and was never really careful with parameters. I did my share of piss-beating them at times.  Except for one soft tube that I bought that way, I have never had a bad 4X1 tube in all that time.  (same goes for 813s)  


T


* eimac- 4-1000A.jpg EIMAC LINEAR SPECS.jpg (262.76 KB, 600x795 - viewed 102 times.)
Logged

Use an "AM Courtesy Filter" to limit transmit audio bandwidth  +-4.5 KHz, +-6.0 KHz or +-8.0 KHz when needed. 

Nothing like a new homebrew rig. Come into the shack, flip on the switches and everything works perfectly.

And, nothing like an old dog.
K1JJ
Contributing
Member
*
Offline Offline

Posts: 8541


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


« Reply #61 on: July 28, 2021, 02:18:56 PM »

And, Rico Suave II, the GG pair of 4X1s using regulated screen and grid supplies.   I found that running regulated screen  voltage in GG improved IMD.  The grid did not need to draw much current, which is always an improvement.


http://amfone.net/Amforum/index.php?topic=34543.0


* RICO SUAVE II Pair 4X1s linear.JPG (325.2 KB, 1280x960 - viewed 91 times.)

* RICO SUAVE II.JPG (322.92 KB, 960x1280 - viewed 104 times.)
Logged

Use an "AM Courtesy Filter" to limit transmit audio bandwidth  +-4.5 KHz, +-6.0 KHz or +-8.0 KHz when needed. 

Nothing like a new homebrew rig. Come into the shack, flip on the switches and everything works perfectly.

And, nothing like an old dog.
Opcom
Patrick J. / KD5OEI
Contributing
Member
*
Offline Offline

Posts: 7923



WWW
« Reply #62 on: October 07, 2021, 01:17:00 AM »

The 5787WA gas regulator. 18 of them came to me in a box of random NOS tubes.

A subminiature gas regulator in a T3 (3/8" dia) envelope about 2" long. It's a ruggedized type rated 98V @ 5-25MA.

These can be had for about $5, and $3 in quantity of >100. 

This little known tube is great for tight spaces and firing is supposedly not affected by incident light.

A possible use in addition to typical shunt regulation duties could be in place of a customary neon lamp for DC coupled vacuum tube circuits and voltage limitation at the front ends of receivers where its higher current ratings could give much increased life. YMMV.


* 5787WA.jpg (157.95 KB, 800x600 - viewed 54 times.)
* 5787WA.pdf (408.33 KB - downloaded 24 times.)
Logged

Radio Candelstein - Flagship Station of the NRK Radio Network.
Pages: 1 2 [3]   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 0.078 seconds with 18 queries.