Re: [Amps] Transfer capacitance, was GI-46B Question

[jeff millar <wa1hco@adelphia.net>]

Art...

Let's put this back on the reflector...it's getting interesting.

All the data sheet from the gda.pl site list values like
input C 10 pF
output C .05 pF
Transfer C 5 pF

But the data sheets at nd2x.net generally look like
input C 10 pF
output C 5 pF
Transfer C .05 pF

Note the swapping of values between ouput C and Transfer C values

Going to the Eimac web site and looking at the 8877 data sheet clears 
this up. The values swap around between grounded grid and grounded 
cathode. Feedthrough and Transfer C measure the same thing.

Capacitance 	Grounded Cathode

     Input
     Output
     Feedthrough

        38.5 pf
0.1 pf
10. pf
Capacitance     Grounded Grid

     Input
     Output
     Feedthrough

        38.5 pf
10.2 pf
0.1 pf


So... make a table of all the Grounded Grid transfer C we can find for 
these tubes

GI-6B 0.2 - 0.3 pF
GI-7B 0.055 to 0.095 pF
GS-9 0.04 pF
GI-46B
GS-31 0.12 pF
GS-35 0.12 pF
8877 0.1 pF

It doesn't appear that any of the various web sites have data on the 
capacitance for the tube...which is a bit strange. But since someone 
built a 432 Amp with the GI-46b, it probably doesn't have the special 
feedback wires like the GI-6B.

A very interesting little bit of investigation.

jeff, wa1hco


Arthur Moe wrote:

> Jeff,
>
> You might want to look here:
>
> http://www.mif.pg.gda.pl/homepages/frank/sheets/018/g/GI7B.pdf
>
> http://www.mif.pg.gda.pl/homepages/frank/sheets/018/g/GI46B.pdf
>
> Note that Transfer "C" is 4.0-5.2 for the GI7B and 5.1-6.4 for the GI46B, the 46 
> only 1.1 to 1.2 more
>
>
> Art
> KB7WW
>
>
>
> jeff millar wrote:
>  
>
> > Interesting...do you think there's a typo on the data sheet?
> >
> > jeff
> >
> > Arthur Moe wrote:
> >
> >    
> >
> > > All,
> > >
> > > If you look around these sites you will find VHF amplifiers using these tubes.  
> > > One
> > > is a commercial builder in europe. See mid power list.
> > >
> > >
> > >
> > > http://www.pollak.sulinet.hu/elektro/pa_rev/pa_rev.htm#mid_vhf
> > >
> > > http://www.westparknet.com/business/ham%20shop/GI46Bamp.htm
> > >
> > > http://www.qsl.net/ok2zi/pa432.html
> > >
> > >
> > > Art
> > > KN7WW
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> > >      
> > >
> > > > Bob the advertisement says the GI-46b is a variant on the GI-7b.  But
> > > > its interesting to read the description of the GI-6B, particularly the
> > > > transfer capacitance (http://nd2x.net/gi6b.html).  Lets compare transfer
> > > > capacitance
> > > >
> > > >   GI-6B   0.25 pf   wires from cathode to anode to make it oscillate
> > > >   GI-7b    0.075 pf   good to microwave frequencies
> > > >   GI-46B 5.1 pf   wow
> > > > (http://www.tubes.ru/techinfo/TransmittingPulseTubes/gi-46b.html)
> > > >
> > > > So it look to me like they used the tube as a power oscillator in
> > > > UHF/microwave application and include extra transfer capacitance to
> > > > simplify the external cavity design.
> > > >
> > > > I belive the statement that the tube is the last generation of small
> > > > triode and it's the most advanced design.  But its not suitable for UHF
> > > > and probably not for VHF.  But in an HF amplifier in Grounded Grid, it
> > > > works fine.
> > > >
> > > > jeff, wa1hco
> > > >
> > > > Bob Bruno - K2KI wrote:
> > > >
> > > >
> > > >
> > > >        
> > > >
> > > > > Are there any examples of an amp that has been built using the GI-46B tube. I 
> > > > > see a guy on eBay selling them rather cheap I think.
> > > > > Anything that I should know about this tube that might steer me away from 
> > > > > getting one?
> > > > >
> > > > >
> > > > > 73, CUL
> > > > >
> > > > > Bob Bruno - K2KI
> > > > > k2ki@starc,org
> > > > > _______________________________________________
> > > > > Amps mailing list
> > > > > Amps@contesting.com
> > > > > http://lists.contesting.com/mailman/listinfo/amps
> > > > >
> > > > >
> > > > >
> > > > >
> > > > >
> > > > >          
> > > > _______________________________________________
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> > > >
> > > >
> > > >        
> > >
> > >
> > >      
>
>
>  

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