Skipp - Your reply has bogus attribution marks.
>more alpha input circuit talk
>-
>>>The Alpha type circuit provides low swr to the exciter,
>: Not low enough for transistor radios unless
>: a tuner is used.
>-
>Based on all the examples I've seen, the swr is low
>enough for most radios.
>-
>>is also relatively broadband, is low in cost and physical -
>>mechanical part requirements and easy to install.
>-
>: The tradeoff of having no flywheel is not small. -
>-
>True but it was a relative trade off Alpha felt would
>work, and it does to a point.
>-
>: Two 8874s in parallel have a driving Z of roughly half
>: of 26-ohms at the negative V peak. This requires
>: matching with a Pi-network/flywheel.
>-
>Since this thread started, I tried to locate the magic
>drive Z value with mixed bag and varied results. An
>amps member reported ~95 ohms for a single tube,
>a W6SAI Radio Handbook says ~160 ohms and now
>your 2 tube value. Someone has to have the real value,
>it's not listed anywhere in plain sight on the Eimac data
>sheet I just looked up on the web.
>-
>The single tube ~95 ohm Z value works with the other
>circuit values in the Alpha circuit diagram.
>-
>>The alternate half cycle is (for the example) pretty much
>>just the resistor network and some C. So the toroidal rf
>>xmfr secondary "load" halves.
>-
>: What is the swamper resistance?
>-
>The Alpha 274 (two hole version) has a total parallel
>swamp R value of 47 ohms as reported on the diagram.
>The R network value in parallel with the 47.5 ohm dynamic
>tube Z works out the 23.6 ohms. The toroid secondary
>value is reported to be 22.2 ohms.
> -
>: With solid-state radios, sans-tuner, the SWR usually
>: needs to be 1.2:1 or better to avoid power foldback. A
>: swamper/transformer is not capable of that.
>-
>Without getting into an argument, I will say that many if
>not most of my common transceivers will drive into swr
>levels higher than 1.2:1 without a problem.
>-
>>It would not provide flywheel, just "better" exciter
>>matching in the alternate half cycle.
>-
>: Exactamente
>-
>Better matching and the broad band response were
>the desired results, above a flywheel effect. I would
>say the engineering goal was reached with the expected
>results.
>-
>skipp
>
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