The AM Forum

WESTERN ELECTRIC CO. / PART NO. 8047 / 50 MMF. 5KV 5 AMP / MADE BY GENERAL ELECTRIC CO., U.S.A. 1943.

(http://dssmhi1.fas.harvard.edu/eMuseumMedia/eMuseumpreviews/C001196_pro.jpg)

In a HB Tuna I just got, it can be switched in just after the input?

Either way, it got busted in shipping...oh, and yes, it is a 50MMF 5KV Transmitting Cap. This much I do know.

Switch it in, added capacitance. Out, less. Some situations require adding capacitance, some inductance, depending on the ant/feedline.

Someone who really knows will be along soon. ;)

It is really up in the air without a schematic Jeff. I would guess some added capacitance to the input tuning cap but it isn't much. without knowing how the tuner works it's just a guess.

Mike

Whoever built it need to extend the tuner range on the antenna used by switching in an additional cap. My fugly tuner has one but without a switch.
I just bolt the hanging JS Leads to the main tuning caps.

You lucky you only got one.. some guy keeps bringin all this STUFF over here! Dang it, my cats want to sleep in that spot. Don't even get me started. If yours is lonely..

fixed value vacuum caps.

Zowie!

A pretty small one.  I have a shoebox full and most of mine are rated at 20kV. 

The BC-610 uses a 50-pf one to pad down the 2-3 mHz plate tank coil to resonance on 160, but you can run 160 on the '610 much more easily without the vacuum cap, by using the stock 1.5-2.0 mHz coil.  The split 150/150 pf, 7 KV plate tuning cap in the '610 has plenty of capacitance for 160, @ the 2000-volt, 250-ma operating parameters of the 250-TH.

The problem with those plug-in fixed vacuum caps is the extra aggravation of having to insert and remove the cap when changing bands, and while you are in the process of changing over, the things have an annoying tendency to roll off the edge of the table and break when they hit the floor.

The tuna in question. I have a Budd cabinet similar to the one this came in just a tad smaller, may just use this for a parts queen to construct my own. Love those buzzardly switches!

(http://i240.photobucket.com/albums/ff43/radiogoon/100_2160.jpg)

(http://i240.photobucket.com/albums/ff43/radiogoon/100_2163.jpg)

Looks like everything you need is there. The little glass vacuum caps are good for incremental tuning, and maybe as a neutralizing cap. They also hold the value well.

Someone needed a bit of extra C to get the toona to do 160 I'll bet.

So being strapped to Mighty Fine Junk my entire Amateur career, would this toona handle what a TX-1 could throw at it RF wise? What could it handle? It was advertised as handling a "KW easy".

There's a story behind this question I can tell only in person, so don't ask.  :-X

A TX-1 Apache  will produce approximately  400W PEP at 100% modulation  (assuming 100W carrier).     A KW rated tuner should handle that.   (Multiply your carrier by  peak modulation by 4 to get the equivalent PEP power.)

Appearance of that toona sez it'll handle your TX-1 but proof is in the pudding, so to speak.  Depends largely on the mismatch you're expecting the toona to handle.

Remember AM service is pretty severe.  You not only have 4X carrier power = PEP at 100% modulation but you have full carrier on during the transmission as well.  SSB is a very low duty cycle mode, as is CW.   As an example, the "250 watt" Johnson matchbox, intended for 250W AM, will handle a KW of SSB and then some.

I necessarily homebrewed a toona for use with my GPT-750.  Even a "3KW" MFJ would fry in seconds, I would suspect.

my biggest problems with tuners has been arcing rather than melting.