The AM Forum

http://www.ebay.com/itm/NOS-NIB-JAN-EIMAC-4PR60B-8252-HAM-Transmitter-Tube-Boxed-5-63-Guaranteed-Good-/290676836608?pt=Vintage_Electronics_R2&hash=item43adb08900

Never seen anything quite like it... nice plate!

4-400 on steriods?

                     _-_-bear

The datasheet says 60 watt plate.
C

http://bunkerofdoom.com/tubes/eimac1/types.html

Tubes with PR in the nomenclature are pulse rated for radar and switching service.  They do just fine on RF, too.

73DG

http://frank.pocnet.net/sheets/084/4/4PR60A.pdf (http://frank.pocnet.net/sheets/084/4/4PR60A.pdf)

looks like in pulse modulator service, they were good for 342 kw at 20kv 18A on the plate.

I have one of those tubes.  I got it in a box full of stuff from an estate. I looked it up at the time and decided that it's not something that I'll ever use, so I did with it what I do with most things that I'll never use: I kept it.

Wonder if one might work in a tube PWM modulator, have the PWM generator drive that tube, then have that modulate the final.

yes, will work for PDM

I seem to remember that the 4PR60 was rated in pulse mode over 100KW RF output for something like a 1 millisecond pulse every second or so. That was a long time ago when I looked at those spec's, so I might be wrong. Anyway the idea I had was to make a pulse 27.185 Mhz (CB channel 19) transmitter with a 1 millisecond > 100KW pulse every second to keep the truckers CB Radio receiver gain throttled back from the fast acting/slow decay AGC.  ;D

Jim
WD5JKO

if 11 meters would open up, you would've probably been able to hear that pulse everywhere.

Ya, PDM not PWM...

Something like a clock freq off the charts... pulses at >10kw...

QSO would be something like this:

"OM, I can't copy ur signal,  but ur modulation seems to be about 4,000% positive!"
"Roger that, running a PDM tube rig... 300watt carrier"
"OM, ur carrier is about 10 over, but you are causing my S meter to pin when you modulate"
" I can turn it down a bit?"
" Thanks but my front end is still overloaded, and I can hear you up a few hundred kHz even though my SDR display says ur not wide..."

etc...

fantasy about much of that of course.

the plate looks hefty...

neat.

I knew you guys would know it right away. :D

                    _-_-bear

curves look good on it. Grid is tough. might make a nice amplifier at low power according to plate ratings.

The 715C is a direct sub and might be easier to find but the audiophools have discovered all versions. Both use a funky socket.

Ive run 715B's on SSB...not too well... but fine on CW and the tube can take serious abuse.

http://tubedata.tigahost.com/tubedata/sheets/061/p/P535-1E.pdf

http://tubedata.tigahost.com/tubedata/sheets/049/7/715C.pdf

I have never seen an audio amp made with one of these, anywhere.

The grid drive is insane...

                  _-_-bear

PWM as in pulse width modulation and PDM as in pulse duration modulation are the exact same thing. PDM as in pulse density modulation is a completely different concept. PWM is the more correct term, pulse duration modulation was one of the broadcast rig manufacturer's (Harris, I thnk) term for what most of us call pulse width modulation. pulse density modulation would be something like equal length pulses, but more or less of them as the modulating signal changes. Pulse width modulation changes the length of the pulse based on the modulating signal. this tube could handle both, but would be capable of more output with pulse density modulation than would be with pulse width modulation.

VERY wise decision.............I do the opposite and when the need arises, I go back out and buy.........BIG junque boxes and large sheds that are organized are the only way to go in this hobby.

You may not believe this, but unlike some of us who may get grief from our wives when we buy stuff, my wife gives me grief when I talk about selling stuff for just the reason you mentioned. Just the other night I got the third degree about deciding to sell a receiver that I recently restored.

You are SO on the money about organization. I have about 2,600 tubes that up until six or seven years ago were just piled up in boxes and scattered about the attic. When I needed a tube that I couldn't find without having to wade through it all I just went out and bought one.  About as dumb and wasteful as it gets. I finally bit the bullet and went through every one, cataloged it, then organized them all neatly in boxes and recorded the whole works on an Excel spreadsheet. I can tell in seconds if I have a particular type, how many I have new and used, and in which storage box I can find it.  Life is good.

How would you like to come over and organize my stuff?

Sure, would love to...as long as I get to take it home and keep it ;D.

Would you mind sharing that Excel format Jim?

Ive just started trying to organize here after it took almost 2 hours to find a couple of NOS 6BJ6's I knew I had.....somewhere.

Id prefer to not reinvent the wheel ;D

Carl

Here you are. Nothing exceptionally creative, but it serves my purpose.  I deleted most of the inventory and left only as much as needed for you to get the idea.  Here's the key to the column headings: U-L means used, loose (in egg-crate dividers); U-B means used, boxed.  There are formulas in Columns B and C that automatically total up the quantities in the individual cells. Hope you find this helpful.

That looks fine Jim, thanks.

Can the tubes be entered in any order and then automatically rearranged in numerical order?  Its been ages since Ive used Excel :-X

Carl

No, at least I'm not aware that Excel can automatically arrange the types as you enter them.  The next best thing you can do is to do a sort from the Filter and Sort function.  After you enter the list of tubes you can select the entire column with the tube numbers, then do a sort.  Be sure to tell Excel to expand the sort to include adjacent cells when it asks you, or you'll sort only the tube number column and not the quantities/locations columns that go with them.  NOTE: you may not want Excel to sort for you, since it may not sort the want you want it to.  Keep in mind that Excel was designed to crunch numbers, and so it does really goofy sorts with alphanumeric values.  Put in a bunch of tube numbers that include a mix of numeric and alphanumeric types with various filament voltages, do a sort and you'll see what I mean. I did the sorting manually when I entered the numbers.  Just insert rows when you need to add a new type in between others.

Jim

Jim,

  So what are your plans for that 0Z4?  ;)

I'm not looking for a project but that is one interesting tube, right up there with big Selenium rectifier stacks.

Jim
WD5JKO

Gonna keep it for someday, just like everything else. I've never been inclined to offer any of my tubes for sale, but I'll sell one off here and there if I see a wanted post and it's a type that I have a few of. I keep them around primarily for my own convenience when restoring radios.

Jim

I go thru a few a year in automotive radios where the customer wants a drive up quick fix. All the paper caps were previously replaced but the 0Z4's often fail to start in 3-5 years or last forever.

I should just build a SS replacement in a dead metal shell since all rebuilds in the last 20+ years use SS or Ive used 6X5's long before that when the socket had filament pins. Its another roundtoit issue ::)

Carl

at some point a boat is a ship, and a shed becomes a building. What is the defining point between building and a shed? Lights? a/c? How can one say when one is in too deep?

fyi, ur in too deep, Patrick!

:D

               _-_-bear

A ship carries boats but not the other way is the Navy definition.

Subs have their own language ::)