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References: [ +subject:/^(?:^\s*(re|sv|fwd|fw)[\[\]\d]*[:>-]+\s*)*\[Amps\]\s+GI7B\s+Question\s+\-\s+Input\s+Matching\s*$/: 9 ]

Total 9 documents matching your query.

1. [Amps] GI7B Question - Input Matching (score: 1)
Author: Lee Buller <k0wa@swbell.net>
Date: Sun, 14 Mar 2010 13:30:13 -0700 (PDT)
I have been reading about the GI-7B Russian made tube. It seems that the input impedance of two tubes is around 100 ohms. Could you not just use a 2:1 transformer to make a match from 50 ohms to 100
/archives//html/Amps/2010-03/msg00257.html (6,891 bytes)

2. Re: [Amps] GI7B Question - Input Matching (score: 1)
Author: ZL2AAA <zl2aaa@paradise.net.nz>
Date: Mon, 15 Mar 2010 10:58:27 +1300
_______________________________________________ Amps mailing list Amps@contesting.com http://lists.contesting.com/mailman/listinfo/amps
/archives//html/Amps/2010-03/msg00260.html (8,143 bytes)

3. Re: [Amps] GI7B Question - Input Matching (score: 1)
Author: James Colville <jimw7ry@gmail.com>
Date: Sun, 14 Mar 2010 17:52:35 -0700
You need the flywheel effect that a C-L-C tank circuit can provide. A broad band transformer is not the answer. This was just discussed here at length not long ago. 73 Jim W7RY ______________________
/archives//html/Amps/2010-03/msg00264.html (9,108 bytes)

4. Re: [Amps] GI7B Question - Input Matching (score: 1)
Author: Roger <sub1@rogerhalstead.com>
Date: Sun, 14 Mar 2010 21:01:42 -0400
Doesn't the Alpha 76 use the broad band transformer along with a bank of resistors to present the proper load? 73 Roger (K8RI) _______________________________________________ Amps mailing list Amps@c
/archives//html/Amps/2010-03/msg00265.html (10,500 bytes)

5. Re: [Amps] GI7B Question - Input Matching (score: 1)
Author: "Carl" <km1h@jeremy.mv.com>
Date: Sun, 14 Mar 2010 21:29:48 -0400
All the 8874 Alphas use that circuit and it works fine. Carl KM1H _______________________________________________ Amps mailing list Amps@contesting.com http://lists.contesting.com/mailman/listinfo/a
/archives//html/Amps/2010-03/msg00267.html (8,311 bytes)

6. Re: [Amps] GI7B Question - Input Matching (score: 1)
Author: "Jeff Blaine AC0C" <keepwalking188@yahoo.com>
Date: Sun, 14 Mar 2010 20:34:56 -0500
Lee, A **SINGLE** tube may run up to 100 ohms. A pair will be 50 ohms or less. Depends on a lot of things though. A broadband match will hurt the amp's efficiency vs. a L/C style matched input with a
/archives//html/Amps/2010-03/msg00268.html (8,901 bytes)

7. Re: [Amps] GI7B Question - Input Matching (score: 1)
Author: "Joe Subich, W4TV" <lists@subich.com>
Date: Sun, 14 Mar 2010 22:01:54 -0400
Yes, but it is not a good design for solid state rigs. The bank of resistors only tempers the impedance swings they don't provide the energy storage flywheel of the tuned circuit. Without the flywhe
/archives//html/Amps/2010-03/msg00269.html (12,070 bytes)

8. Re: [Amps] GI7B Question - Input Matching (score: 1)
Author: "Carl" <km1h@jeremy.mv.com>
Date: Mon, 15 Mar 2010 09:30:44 -0400
I wonder how much it really hurts the IMD. The 8874 is capable of much better IMD than most SS exciters and GIGO still rules the band. The SB-230, MLA-2500 and all those Alphas used resistive inputs
/archives//html/Amps/2010-03/msg00275.html (13,077 bytes)

9. Re: [Amps] GI7B Question - Input Matching (score: 1)
Author: "DF3KV" <df3kv@t-online.de>
Date: Mon, 15 Mar 2010 17:34:46 +0100
The transconductance of that tube is given in the original data sheet at 23mA/V, so the input impedance of a single tube will be 43 ohms. A 2:1 transformer will match to 25 ohms. 73 Peter I have been
/archives//html/Amps/2010-03/msg00276.html (8,877 bytes)

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