[VHFcontesting] Mix 31 or 43 ferrite material for use at 50 MHz ?

[Mark Spencer]

Thanks that is helpful.  

 My use case is more along the lines of pro actively putting ferrite cores on USB, audio and other similar cables that are used in a typical portable 50 MHz station but I suspect the underlying physics don't change much.    

Mix 43 is available over the counter at the local electronics store whereas I need to order Mix 31 so the performance of Mix 43 is still of interest to me in case I need another snap on choke the day before an outing and I discover I have used up my stock pile of Mix 31 (:

One day I should embark on a measurement campaign and actually measure the impedance of various chokes on cables similar to the ones I am using.  These days I tend to put more emphasis on actually trying stuff out in the field rather than making measurements in the lab.  It is nice to hear that others are doing lab work along these lines.

73
Mark S
VE7AFZ

mark at alignedsolutions.com
604 762 4099

> On Jul 21, 2019, at 9:02 AM, Sean Waite <waisean at gmail.com> wrote:
> 
> Per Jim Brown, K9YC, one of the experts in the field -
> 
> "I recently did some work on chokes for 6M and posted the result to an 
> email reflector devoted to grid chasers for that band. Two turns of 
> RG8-size coax through a 1-in id. #31 clamp-on is optimum for 6M, and 
> yields about 1K ohms resistive choking Z. I recommend at least two such 
> chokes in series at the feedpoint. For RG8X or RG400, two turns through 
> TWO 3/4-in i.d. cores is optimum for 6M, and yields about 1.2K choking 
> Z. Again, use at least two such chokes in series.
> 
> For 2M, use multiple #31 clamp-ons, sized to fit the coax. Use the link 
> below to select the size that fits your coax. Each will provide about 
> 250 ohms choking Z on 2M. Do not wind turns, just clamp them onto the 
> coax. I would use at least five, and ten is better. :)   Arrow is a good 
> vendor for parts they have in stock.
> 
> https://www.fair-rite.com/product-category/suppression-components/round-cable-snap-its/lower-broadband-frequencies-1-300-mhz-31-material-round-cable-snap-its/
> 
> 73, Jim K9YC
> "
> 
> 
> Hope that helps
> 
>> On Sun, Jul 21, 2019, 10:37 Mark Spencer <mark at alignedsolutions.com> wrote:
>> Hi:
>> 
>> I'm curious if anyone has any thoughts about the relative merits of using mix 31 or mix 43 ferrite snap on cores for pro active use on interconnection cables at 50 MHz.   Over the years I have used both and have managed to avoid any notable RFI issues in my portable setups.
>> 
>> I figure for HF Mix 31 is almost a no brainer, but I am less certain about the best choice at 50 MHz.   
>> 
>> Thanks in advance for any comments.
>> 
>> 73
>> 
>> Mark S
>> VE7AFZ
>> 
>> mark at alignedsolutions.com
>> 604 762 4099
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