EMRFD Message Archive 675

Message Date From Subject
675 2007-04-28 06:17:40 Ed Almos Binocular Core Selection For H-Mode Mixer
A quick question. Which would be the best binocular core to use on an
h-mode mixer working at HF, a BN43-2402 or a BN73-2402?

Edward Almos HA6SST
676 2007-04-28 09:38:43 Baruch Zilbershat... Re: Binocular Core Selection For H-Mode Mixer
677 2007-04-29 12:12:40 Giancarlo Re: Binocular Core Selection For H-Mode Mixer
678 2007-05-01 01:22:00 Ed Almos Re: Binocular Core Selection For H-Mode Mixer
OK, thank you for the replies. I have some type 43 cores in stock and
can go ahead with the project. Somebody told me that type 73 cores
must be used in this applicati
681 2007-05-01 14:48:41 Giancarlo Re: Binocular Core Selection For H-Mode Mixer
685 2007-05-01 16:09:35 Jim Miller Re: Binocular Core Selection For H-Mode Mixer
see www.w8ji.com who recommends 73 mix for receive front end apps.


jim ab3cv

----- Original Message -----
687 2007-05-01 16:31:24 Kevin Purcell Re: Binocular Core Selection For H-Mode Mixer
In this article?


> I mainly use 73 material for receiving applications in LOW POWER
> applications between .1 and 30 MHz. 73 and similar core materials
> generally minimize the turns count required without inducing
> excessive loss. One of the best indicators of correct core
> selection is looking at the turns required. You'll notice most of
> the transformers I use have only one or two turns for every 100
> ohms of impedance. My 75 to 450 ohm Beverage transformers, for
> example, only require two-turn primary and 5-turn secondary
> windings. A low "turns count" is a good indicator the correct core
> size and core material is being used.
and (remember he's talking about TX baluns here)

> At higher power levels, it is necessary to move to lower loss
> tangent and higher curie temperature materials like 65, 61, or (in
> extreme cases) 43 materials. Even a fraction of a dB loss produces
> significant heating in small cores when power level is in the
> kilowatt range. The loss DIFFERENCE in non-resonant applications
> between lower and high ui ferrite cores isn't significantly
> different, but heating can be much less!
Of course there's


> MATERIAL 43 (µ = 850) High volume resistivity. For medium frequency
> inductors and wideband transformers up to 50 MHz. Optimum frequency
> attenuation from 40 MHZ to 400 MHz. Available in toroidal cores,
> shield beads, multi-aperture cores and special shapes for RFI
> suppression.

> MATERIAL 73 (µ = 2500) Primarily a ferrite bead material. Has good
> attenuation properties from 1 MHZ through 50 MHz. Available in
> beads and some broadband multi-aperture cores.

43 is recommended for wideband use from 1 to 30MHz but 73 is
recommended from .2 to 15MHz. So on 160m through 20m you could use
both and you'd wind fewer turns (for a given reactance).

It would seem 43 would be the preferred choice but I suspect both
would work with 73 being better at lower frequencies.

Or, EMRFD way, you could try both and measure the difference (it's a
50c part).

692 2007-05-02 02:08:59 Giancarlo Re: Binocular Core Selection For H-Mode Mixer
Hi Jim,

thanks for your note.

#73-2402 should be good for H-mode mixers to convert from 8 to 10MHz
IFs to 455kHz 2nd or 3rd IF.

#73 Not a common value this side.