On 8/6/2014 8:31 AM, Carl wrote:
31 and 43 mix are the popular ones in the 2-30 MHz range for common mode
suppression; 31 wins at 160 and 80, but 43 is better in the 7-30 range.
I would amend that only to say that #31 and #43 are roughly equivalent in
the 5-15 MHz, range, #43 is slightly better above 15 MHz. #43 is a bit
less expensive than #31, but the cost difference disappears if you buy #31
in quantity. My last group purchase of #31 2.4-in cores was for 1,100
pieces, about two years ago. We paid about $4.
Because #31 is so much better on 80 and 160, because it is more broadband
below 15 MHz, and because it remains effective through the HF range, I
long ago made the engineering decision to buy #31 in quantity for ham HF
applications. If I were ONLY working above 80M, I would look at pricing
on #43 in the quantities I needed.
73, Jim K9YC
Im just basing it on some personal experience but havent run any lab tests.
On a 40M inverted V with apex at 55' Id been using a pigtail with 43 for
years, switching to 31, and no ferrite I couldnt hear any difference, both
worked well. I mentioned the 43 since it is much cheaper.
For 20M I used a 3 el HB monobander at 60' on another tower and the 43
seemed a hair better.
Not exactly scientific and with a wide range of mix tolerances Im not going
to worry about it, a few extra turns of coax would have sufficed.
Both antennas are part of the AM station and were easy to get to.
Since I dont run enough power to cause non linearities that isnt a concern
on TX.
Carl
KM1H
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