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G0FTD > QRP 23.06.05 23:01l 38 Lines 1337 Bytes #999 (0) @ WW
BID : C40893G0FTD
Read: GUEST DG9NBR
Subj: ZL4AJS and ferrites
Path: DB0FHN<DB0RGB<DB0AAB<F6KFT<LX0PAC<DB0NDK<DB0WST<DB0ACH<DB0ACC<DB0GOS<
DB0EEO<DB0RES<DK0WUE<7M3TJZ<HG8LXL<CX2SA<GB7YFS<GB7CIP<GB7SXE
Sent: 050623/1741Z @:GB7SXE.#38.GBR.EU #:33973 [Hastings] FBB7.00i $:C40893G0FT
From: G0FTD@GB7SXE.#38.GBR.EU
To : QRP@WW
> My next hurdle is the cores for the driver transformer and RFC. I'm using
> some pretty poor F43 material toroids at the moment and they are only
> rated up to 1 MHz.
* The ferrite cored transformer provides both signal coupling as well as
impedance transformation - both of which can be done by using "normal"
lumped components.
The above may be an alternative method of doing the same thing in
circumstances where physical size is not a problem.
* You could just use a "stolen" ferrite rod to make a suitable
transformer.
It wont matter if your using a rod or a toroid when experimenting.
A bit of experimentation will find the optimum turns and ratio.
It's not that hard, and you'll be doing just the same as any so called
professional when designing a circuit so don't think you need to be
a Professor in Maths or have access to the super duper computer models.
I use "stolen" ferrite rods from AM broadcast recievers for my baluns
working 1-54Mhz and they work well without much loss.
If they were lossy I'd not be working all around Europe with 2 watts
and an indoor loop on 50Mhz nor would I be working packet sysops on
80m ssb with 2 watts either - as both G6CRV (of GB7CRV and G8PZT of
GB7PZT bbs' will confirm - 200 to 500 miles away).
Hope this helps.
Regards - Andy
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