>
>Mike(W5UC) & Kathy(K5MWH) wrote:
>>Let's assume we have four toroids of the same physical size, and
>>there is one each of # 31, 43, 73, and 77 mix. Each is wound to
>>isolate the coax, and each has a 5 turn primary and a 15 turn
>>secondary. How does the performance of each differ and why?
>>
>>Hi Mike,
>>
>I won't waste bandwidth explaining why toroids and 5 turn primaries
>are undesirable. Others will do that.
>What I have to offer is the fact that 73 type toroids are not
>marketed by anyone, as far as I know. However, I once obtained four
>of these that had been use for material evaluation purposes by the
>manufacturer. I wanted these for reflection transformers in
>reversible beverages where the self impedance would have to be up in
>the 2K region. These worked OK, although they still required too
>many turns for my liking. When adding more Beverages, I switched
>completely to binocular cores for the reflection transformers, as
>well as the "near end" transformers. To get the 2K plus impedance I
>attached a pair of half-inch long binoculars together, end-to-end
>with a couple of small droplets of crazy glue. (There are one-inch
>long binoculars available, but I was in a rush, and I had a large
>stock of the half inch ones available). These are much easier to
>wind than toroids, as well as making more efficient use of the
>ferrite material.
>
>I might point out that Amidon is not the only distributor of
>ferrites, although it seems to be by far the best known to Hams. I
>have had very good service from CWS Bytemark. I don't believe the
>manufacturer, FairRite is too happy about filling small orders for Hams.
>
>Incidentally, I am surprised that many more people are not using
>reversible Beverages. My lot is long and narrow - 550 feet by
>about 3000 feet, with the house near one corner, and reversible
>Beverages are the only way I can cover 8 azimuths conveniently. I
>am in the process of adding phased Bevs (broadside-phased with 330
>feet spacing for the short direction (550 feet), and end-fire feed
>with the 850 foot-long ones aimed at Europe.
>If anyone else has had experience with phasing reversible Beverages,
>perhaps with provision for varying the phase of end-fire
>configuration, I would be interested to hear their experience.
>
>Bert, VE3QAA
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