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THE AM BULLETIN BOARD => Technical Forum => Topic started by: WU2D on June 06, 2020, 09:20:44 AM



Title: Whatsit?
Post by: WU2D on June 06, 2020, 09:20:44 AM
So what is this?


Title: Re: Whatsit?
Post by: w4bfs on June 06, 2020, 09:25:14 AM
did ur Ohmmeter tell u anything ?


Title: Re: Whatsit?
Post by: Tom WA3KLR on June 06, 2020, 09:29:18 AM
UHF/microwave triode? But what number!


Title: Re: Whatsit?
Post by: MikeKE0ZUinkcmo on June 07, 2020, 01:28:21 AM
Tom is correct, I believe.   I faintly remember seeing those 50/60 years ago.   


Title: Re: Whatsit?
Post by: WU2D on June 07, 2020, 06:39:08 AM
AH it is a 4042. I see that number and 26720 printed on the other side of the heatsink ring.


Title: Re: Whatsit?
Post by: Tom WA3KLR on June 07, 2020, 12:44:55 PM
This tube is not listed in 'Frank's Tube Data' website nor in my 9 volumes of RCA HB-3's.  But it is listed in Ludwell Sibley's 'Tube Lore' in the RCA chapter:
"Xmtg. glass pencil triode; pulsed osc. giving 425 W pulse at 1.7 GHz."  That's all.

Must have been rarely used and rare, nice find.  The phenolic insulator and lacquer has that WWII look.
 - - - - - -

OMG! I just did some research on the web - it's the oscillator tube in the HP 608 r.f signal generators!


Title: Re: Whatsit?
Post by: WU2D on June 07, 2020, 08:14:25 PM
So now you know what I just parted out this weekend!


Title: Re: Whatsit?
Post by: KA2DZT on June 07, 2020, 11:32:31 PM
I parted out a HP-608 a few years ago.  The UHF triode looked familiar. I still have three more HP-608s


Title: Re: Whatsit?
Post by: Tom WA3KLR on June 08, 2020, 04:13:16 PM
I have a Navy version of a HP608 here.  It is similar to the D model as I recall.  I had to do a fair amount of work on it originally. It was working fine the last I used it, which was a long time ago.  I keep it in case I need to generate 2 signals at the same time.


Title: Re: Whatsit?
Post by: Opcom on June 08, 2020, 07:40:46 PM
Any time I get an HP 410 VTVM that is unrepairable, I check the probe for the little tube in there. It's getting rare. It's on us all to always check things if they have to be scrapped.
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