[RFI] Common mode choke on 4 Square feedlines without skewing phasing?

[Grant Saviers]

I think your bend radius number should be 30mm (1.18") one time per 
Hubner & Suhner not 0.175".  About the same as RG142 50 ohm.

Grant KZ1W

On 2/19/2019 15:21 PM, John K9UWA wrote:
> What if the outside temperature is already 95 to 100 degrees and then we start
> heating up this RG-179 with the loss it has?    So my question is is there another
> 75 ohm coax that could be wrapped properly around some type of Mix 31 core as
> well as having less loss and therefore less heat?
> Maybe it isn't quite 10K ohms Rs on 160m or 13.5K Ohms Rs on 80m?
> Maybe RG-302/U ?? Bending radius is 0.175" even though it has a solid center
> conductor. Power handling is better than RG-179 and loss is a bit less. Total
> diameter is 0.202" power handling listed at 1700 watts at 400 mhz.
> On an FT-240 #31 core ID is 1.4" perhaps you could get to 17-18 turns on that
> core. Yes that isn't 27 turns for 160m or 24 for 80m Perhaps two stacked FT-240
> #31 cores would make the 10K Ohms numbers?
> 
> John k9uwa
> 
> 
>>
>> Here are my recommendations for 75 ohm transmitting chokes wound with
>> FEP or PTFE mini-coax RG179 on 2.4-in o.d. #31 toroids.  Turns are wound
>> close-spaced (touching on the inside diameter).  As previously noted,
>> this coax has fairly high loss, so the choke should not see more than
>> the approximately 360W it would see when divided equally between four
>> verticals, and even at that power level, it MUST be exposed to air.
>> Note that I am NOT saying that they CAN handle this much power -- that's
>> up to others to verify.
>>
>> 160M:  27 turns   12K Ohms Rs
>>    80M:  24 turns  13.5K Ohms Rs
>> 40M:  22 turns  10K Ohms Rs
>>
>> To develop these recommendations, I wound Grant's coax on the same four
>> cores at the limits of recently purchased cores used for my recent
>> RG400, THHN, and Teflon pair 2018 Cookbook, tabulated the data, and
>> chose worst case (lowest) values for Rs on each band.
>>
>> 73, Jim K9YC
> John Goller, K9UWA & Jean Goller, N9PXF
> Antique Radio Restorations
> k9uwa at arrl.net
> Visit our Web Site at:
> http://www.JohnJeanAntiqueRadio.com
> 4836 Ranch Road
> Leo, IN 46765
> USA
> 1-260-637-6426
> 
> _______________________________________________
> RFI mailing list
> RFI at contesting.com
> http://lists.contesting.com/mailman/listinfo/rfi
>