Re: Tube Coils (fwd)

To: tesla-at-pupman-dot-com
Subject: Re: Tube Coils (fwd)
From: Tesla List <mod1-at-pupman-dot-com>
Date: Tue, 25 Feb 1997 22:25:16 -0700 (MST)
Approved: mod1-at-poodle.pupman-dot-com


---------- Forwarded message ----------
Date: Tue, 25 Feb 1997 09:59:00 -0500 (EST)
From: richard hull <rhull-at-richmond.infi-dot-net>
To: Tesla List <mod1-at-pupman-dot-com>
Subject: Re: Tube Coils (fwd)

At 09:33 PM 2/24/97 -0700, you wrote:
>
>
>---------- Forwarded message ----------
>Date: Mon, 24 Feb 1997 11:22:22 -0500
>From: "Robert W. Stephens" <rwstephens-at-headwaters-dot-com>
>To: Tesla List <mod1-at-pupman-dot-com>
>Subject: Re: Tube Coils (fwd)
>
>> Date:          Sun, 23 Feb 1997 21:06:18 -0700 (MST)
>> From:          Tesla List <mod1-at-pupman-dot-com>
>> To:            tesla-at-pupman-dot-com
>> Subject:       Tube Coils (fwd)
>
>> 
>> 
>> ---------- Forwarded message ----------
>> Date: Sun, 23 Feb 1997 16:45:50 -0500 (EST)
>> From: VonPostel-at-aol-dot-com
>> To: tesla-at-pupman-dot-com
>> Subject: Tube Coils
>> 
>> Noticed a request for information on figuring perimeters for vacuum tubes.
>> These all give the method for calculating tube operation when you have the
>> characteristic curves.
>> 
>> Application Bulletin Number 4
>> "Class C Amplifier Calculations"
>> Eitel-McCullough, Inc.  Copyright 1948
>> 
>> I haven't asked  EiMac for help in a lot of years, but they used to be very
>> generous with their assistance.  At one time they made a line of triodes
>> having a large reserve of cathode power.  That makes them particularly
>> adaptable to pulse type applications.  Typical of these are the 250-TH,
>> 250-TL, 304-TH, 304-TL, 450-TH, and the 450-TL. The number of the tube is the
>> plate dissipation in watts. TH means a "high mu" tube and TL means a "low mu"
>> tube.  All of the foregoing were designed to run "Cheery Red" at maximum
>> plate dissipation. All are radiation cooled. (Fans not needed if there is
>> free circulation of air.).  They can all be operated up to about 30 MHz with
>> out de-rateing because of frequency limitations.
>> Type:     Filament Voltage:   Filament Current
>> 250T-			5.0-5.1			10.5 A.
>> 304T-			5.0				25 A
>>          or		10				12.5 A.
>> 450T-			7.5				12 A
>> 
>> As a suggestion, if you are think about building a coil which will be pulsed,
>> take a close look at the 304-TH or 304-TL.  They were originally designed for
>> such service in radars and  were pulsed into the megawatt power region.
>snip
>> 
>> Hope this is of help.
>> 
>> 
>VonPostel, All,
>
>I just scored some 1949 vintage RCA HF military groundstation 
>transmitting equipment.  Each of the four transmitters had a pair of 
>gorgeous 450TH Eimac triodes.  I thusly have the sockets and 
>filament transformers as well.  Two of these tubes had broken 
>filament strands from shipping abuse and are now being displayed 
>proudly in my dining room china cabinet.  They are very pretty being 
>about a foot tall with a 5 inch diameter globe containing the working 
>ingredients.
>
>By looking at the remains of the filament in one of these damaged 
>tubes I don't see any white oxide color on these thin tungsten 
>needles.  Can anyone out there establish for certain whether these 
>are straight, unthoriated tungsten filaments?  I guess I could tell 
>from the filament color but I haven't plugged one of these jewels in 
>yet.  This tube looks about the electrical equivalent of an 833-A.  
>For performance/cost and modern times availability I'd build 833-A's into a
>vac-tube TC, but for a piece of tabletop art, I'd certainly want these in it.
>
>I've NEVER run across any of these tubes surplus, so I suspect they 
>are rather rare nowadays.
>
>rwstephens
>
>
>Robert,

You are the guy who put me onto "Pulse Generators" in the MIT RADLAB series!!!

Check it out.

The 304 TL has non-thoriated fils and is suitable for regular radio linear
work.  The 304 TH is a special variant made especially for Radar pulse
systems during WW II and has a thoriated tungsten filament.  These TH tubes
were special jobs and capable of much higher peak currents demanded in the
pulsed mode of operation.  All this is covered in great detail in the book
"pulse generators" with lotsa' tables and diagrams on the 304 TH
specifically.  I hope I have sort of returned the favor here using the same
book.

Thus, your 450 TH is also a later ramped up, beefed up, version of the
earlier and ubiquitous 304 TH and, itself, has thoriated fils.  The "TH" is
the give away.

Richard Hull, TCBOR