Jeff,
Just take a look at
http://www.tubes.ru/techinfo/TransmittingPulseTubes/gi-46b.html
and you will find that transfer C is between 5.1 - 6.4 pF and input C is
from 14.5 to 18.5 pF.
Looks like the true is somewhere beyond :)
73, Remi LY4XX
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
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>_______________________________________________
>>>>Amps mailing list
>>>>Amps@contesting.com
>>>>http://lists.contesting.com/mailman/listinfo/amps
>>>>
>>>>
>>>>
>>>>
>>>
>>>
>>>
>>>
>
>
>
>
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