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

[R.Measures]

Jeff --  I have seen Eimac data sheets where the (g-g config)  
feedback-C and the output C were inadvertently swapped.

On Oct 15, 2004, at 8:53 PM, jeff millar wrote:

> 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 at starc,org
>>>>>> _______________________________________________
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>>>>>> Amps at contesting.com
>>>>>> http://lists.contesting.com/mailman/listinfo/amps
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>> _______________________________________________
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>>>>>
>>>>>
>>>>>
>>>>
>>>>
>>>>
>>
>>
>>
>
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>

Richard L. Measures, AG6K, 805.386.3734.  www.somis.org