Any info on the GMI-11 Russian tetrode...

[K5WLF]

While chasing things on the Net the other night, I ran across a tube I'd never heard of before. It's the GMI-11, a Russian tetrode designed for pulse use in airborne radar. Specifically, in the SU-27 and Mig-29. If it will hold up to service in those birds, it's tougher than most humans I know (myself included).

Here's the URL where I found it: http://qro-parts.com/product_info.php?products_id=82

The spec sheet is attached. I have plate iron that will make 1500 VDC without a doubler, which is one of the things that attracts me to this tube. I hate voltage doublers.

I make no claim of being a tube amp designer. Given a good design and schematic, I can build one. But, at this point, I can't design one. If anyone has any info, experience or ideas on building an amp with this tube, I'll welcome the input.

TIA,
ldb
K5WLF

[W3RSW]

Plate dissapation is about half way between the venerable 4D32 and the 813.
This tube would make a very nice, compact AM xmitter with a pair modulated by a pair.

I wonder what kind of audio amp specs, plate load for mod transformer, distortion, etc. the tube has.
In amateur service the distortion wouldn't have to be super Hi Fi.

Buy several and experiment. Here's your chance to corner the market. 

Price, oxide cathode, high emission filament, low current filament, boat or airplane voltage application for the filament, reasonably low plate voltages...   What more could you ask?

[K6IC]

Have seen this tube on the QRO site,  and wondered about it,  too:

Here is a link, a chance to learn more about the tube and brush up on your Russian,  too:
http://ru3ga.qrz.ru/LAMP/5.htm

This is the RU Data Sheet:
http://www.gstube.com/data/2969/

Will Google around some more ...    GL  Vic  

[W3RSW]

I notice QRO's charging $109 for it.
But spec sheet from Russia says,"

   GMI-11  71.64 US$         

-so customs and shipping would call for a bulk buy.

I wonder if they have warehouses full of these rugged tubes?
Look at how the elements are aligned with supports sealed in glass both top and bottom.

One neat bottle;- compactron on steroids.

[W2PFY]

That store also has an ebay site. If you go on the search on ebay and punch in that number you'll come up with their site, with a beautiful example of a home brew amp with the plates glowing red.

[K5WLF]

...a beautiful example of a home brew amp with the plates glowing red.

Only thing wrong with that amp is that there's no window in the front to watch the glowstuff.

Sure like the moderate drive requirements too. It'd work well with the DX-60A the postman dropped off at my house today. I'm gonna have to get some xtals or the VFO before I can get it on the air. But the hollow-state state in my shack is getting closer.

Anybody got an HG-10 they want to sell?

73,
Larry
K5WLF

[K6IC]

Yea,  Terry,

Saw that image.  A beautiful amp,  sure looks commercial to me,  but is probably not,  given the stated purpose of the tube.

Scroll down this page a bit,  think that this is what Terry was referring to:

I cannot get the e-bay link to post correctly --linewrap problem,  so,  not that anyone needs it buy this line in Google should do it -- first non sponsored link:

gmi-11 tube data ebay

One other note,  have done business with QRO Parts before, and they do a very good job.  At least when dealing with them directly,  the prices noted are really FOB Russia.  Even if the parts are in Texas,  there is a significant shipping cost not shown until one checks out.  Basically,  the heavier the part the more this non-obvious cost is.  Not anything dishonest,  just something that is not known until the checkout process is done.

Think some one here should snag some and build an amp.  Oh,  and on the noted prices on one of the other pages,  that is probably an old price.  Lotta prices @  QRO have risen 10-15% in the past 6 or so months. Perhaps our Dollarito is getting smaller yet ... etc     Vic

[K5WLF]

This should solve the linewrap problem: http://tinyurl.com/yj97q7g

The listing says the amp is HB. It's a nicely done project.

Wish I was good enough to design an amp using a pair of those tubes. Back to the books I guess.

The QRO-Parts.com website is showing the tube with socket for $109.50. Five bucks less than the ePay listing.

73,
ldb
K5WLF

[K6IC]

Hi Larry,

Thanks for the tiny fix.

According to the QRO site,  two of these tubes with sockets delivered to my door in CA
2ea  GMI-11 & Skt 219.00
     Total shippping $34.00
               Total: $253.00

Not too bad,  and with that window ... COOL.

[K5WLF]

Hi Larry,

Thanks for the tiny fix.

According to the QRO site,  two of these tubes with sockets delivered to my door in CA
2ea  GMI-11 & Skt 219.00
     Total shippping $34.00
               Total: $253.00

Not too bad,  and with that window ... COOL.

TinyURL is like a Gerber Multi-Tool to me. Can't live without it. It's one of the buttons on the toolbar in Firefox. 

Yeah, the price on those tubes is definitely right.

I emailed QRO-stuff and asked if they had the skemat for the amp in the ad. He said they didn't, but sent me a 'one-holer' schematic that might be a starting point for designing an amp using a pair of them. The one I just got from him is the attached GIF. The JPG is a partial drawing that was part of the English language spec sheet I got yesterday.

Gentlemen, I propose the 2010 AMFone GMI-11 Design Challenge. An amplifier designed by a 'committee'. Yep, us. There is a lot of knowledge and talent in this group. Shall we put it to work? I'm not capable of designing the actual RF circuits, but I can make some contributions in power, control, layout, panel design, etc. Anybody else want to play?

Basic parameters:
Uses a pair of GMI-11 tubes
Capable of legal limit on AM (figure 100% duty cycle for old buzzardly transmissions)
Ep = 1500 (because I already have the PS)
160 - 10 meter coverage with an easy option to eliminate 15 & 10 (I just want 160, 80, 40 & 20)
20-30 watts drive for full output (lets 100 W riceboxes be used as AM drivers)
Pi-network output

Let's see what we can come up with -- and I'll build the first one. With a window.

Whaddaya think?

73,
ldb
K5WLF

[W2PFY]

Saw that image.  A beautiful amp,  sure looks commercial to me,  but is probably not,  given the stated purpose of the tube.

There are some truly gifted people out there that can build great looking things that are functional. someday I'll start a thread with a two meter homebrew transmitter that an engineer built. It's a work of art but that's for another time.

 

[KM1H]

That tube was discussed elsewhere when it first surfaced. Basically at that price it is an expensive curiosity considering how many NIB 813's and 4-125A's are still available. I believe the initial price was $99 delivered in the USA.

Size wise it is the same height and slightly narrower than a 3-400Z which would put it into the roughly 300W dissipation area if it was forced air cooled. Note it was not air cooled in its military application and Ive no idea of the total area of the anode...it is pretty impressive tho. With forced air cooling it would compete with the 4-250A or even a 4-400A in less than full bore comparisons and those are also pretty cheap.

Carl

[W3RSW]

Well I have some 813's an' all that but this tube's coolness factor, anode glow, really rugged hi-G application, and probably a very thick pyrex equiv. envelope makes it waaay neat.

Oh, and meant to add, why not just buy a couple and modify an existing two holer  amp.?

 Wouldn't take much to change out from a couple of 813 sockets, also the fil. xformer to 24 to 28 volts and make sure the plate voltage is no more than 2000.
Taps changed on the pi net, if necessary, should do it. 

[K5WLF]

Well I have some 813's an' all that but this tube's coolness factor, anode glow, really rugged hi-G application, and probably a very thick pyrex equiv. envelope makes it waaay neat.

Oh, and meant to add, why not just buy a couple and modify an existing two holer  amp.?

 Wouldn't take much to change out from a couple of 813 sockets, also the fil. xformer to 24 to 28 volts and make sure the plate voltage is no more than 2000.
Taps changed on the pi net, if necessary, should do it. 

Hmmm, Rick... That's a creative idea. My original thought was to build one from scratch (since I was just given a 7' rack cabinet it'd be rack mount) with a window in the front to watch the wonderful glowstuff. And my PS is rack mount too. Of course, I could do the conversion as a testbed and build the showpiece once it's perfected.

Still, if anybody comes up with a good design, I'll build the "purty one" right out of the gate 

ldb