Re: Large-Scale FSL Experimentation Tripped Up by Soviet Surplus Scammers on eBay


db4iw
 

I think the Q value of 180 for the Ferropribor rod does not mean a lot - as long as we don't know anything about the coil which they used for testing and measuring.

I have found an interesting article about optimizing the performance/ferrite volume ratio:
H. Blok & J. J. Rietveld, Induktive Antennen in modernen Rundfunkempfängern, in: Philips Technische Rundschau, 16. Jahrgang Nr. 6, Dez. 1954, Seiten 149-163.
Amongst other things, the authors write about stacking ferrite rods with distributed inductivities (I have posted the picture "Ferrit_Stockung.jpg" to the files area). The distance between the rods should be far enough that no coil has magnetic influence on the next one (e.g. 10 cm). For a given value of L every coil must have the inductivity of L/p. As a secondary effect, this will make it easier to keep the distributed capacitance of L small. The authors claim that H_eff in this case is proportional to the square root of the ferrite volume wehereas it is proportional to the fourth root if one (bigger) rod is used. (Hopefully, my poor English is comprehensible. Otherwise I would post the paragraph in German and ask someone to translate it.)

73, Fritz

Michael: Ich habe auch in Heidelberg studiert (1967/69).

--- In ultralightdx@..., "Michael" <michael.setaazul@...> wrote:

The proven quality and specification of ferrite rods is evidently a crucial issue,
as referenced by Kevin and Fritz. I think we should focus on this just as
much as on FSL design. I have put my experiment intentions on the back-burner -
bzw. auf die lange Bank geschoben - until we have more data on these issues.

Michael UK

Fritz : ich habe seinerzeit in HD studiert.

----- Original
Message ---------------------------------------------------------------------------------------

From: "gmosherat"
. . . . .
Also, I did receive a large quantity of 100x20x3 "Russian Ferrite" bars from a East European Ebayer.
So far I've had little time to test, initial results were not favorable, perhaps I got some cheap
Ferrite substitute?

Gregory

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