[600MRG] Super Chocker

Fri Feb 21 21:08:53 CST 2014

Wonderful Carl.

I had forgotten the type and Mike - you met him and discussed his antenna
at NearFest in NH several years ago before he passed on - had  gone through
the list.

Which is the material that will produce the most inductance, handle the
most power safely at 400 to 500 kc/s?

Is it the 31 mix you mentioned?

You mention RG-58, 8X, 42 and 400, are they all cables?

The 400 must be LMR-400 but what is the 42 cable you mention?

Thanks for sending the info.

DR

On Fri, Feb 21, 2014 at 7:53 PM, Carl <km1h at jeremy.mv.com> wrote:

> Hi David
>
> Palomar is likely the most expensive souurce for those ferrites and either
> Mouser or Digi Key the better choice.
>
> The Fair-Rite part is 2643803802 but is far from ideal at 600M; it isnt
> even great on 160.
>
> The 31 mix is the "in thing" these days on 80M and lower and its part is
> 2631803802.
>
> I suggest reading  the links below on how to address common mode.
>
> http://audiosystemsgroup.com/RFI-Ham.pdf
>
> and
>
> http://audiosystemsgroup.com/NCDXACoaxChokesPPT.pdf
>
> I havent found any common mode problem that couldnt be solved by no more
> than 2 of those cores and enough turns depending upon frequency. Adding
> another choke several feet away is more effective than stacking 5-7 and
> using an intermediate ground rod or three at intervals is often very
> effective. See ON4UN's Low Frequency DXing 5th edition for indepth
> discussion..
>
> At 600M power levels RG-58, 8X, 42 and 400 should take care of everything
> and get lots of turns.
>
> I use 31 mix to 20M and 43 from there to 2M at 1200-1500W and all over the
> house for noisemakers.
>
> Carl
> KM1H
>
> ----- Original Message ----- From: "D.J.J. Ring, Jr." <n1ea at arrl.net>
> To: "600 meter group" <600mrg at w7ekb.com>
> Sent: Friday, February 21, 2014 6:45 PM
> Subject: [600MRG] Super Chocker
>
>
>  Michael Laronda, WA1OMI used a highly effective torroid from Fair-Rite who
>> manufactures them.  I remember the Mix 43 part, but not the rest of the
>> designator, but some snooping around on eBay I found what Palomar
>> Engineers
>> is using in their Super Choker™
>>
>> ♥♥♥♥♥♥♥♥♥♥♥♥♥♥
>>
>> The Super Choker™ uses eight FT-240 Mix 43 ferrite toroids and a five foot
>> RG-8 coaxial cable preassembled with nylon ties. There are 4 turns of
>> cable
>> through the ferrite cores which is the maximum turns for cable with
>> connectors as supplied. All you need to add are two coaxial barrel
>> connectors to connect to your existing cable. We have measured impedances
>> of 2-3K between 1 and 10 Mhz with our AIM 4170 and it really works well in
>> reducing common mode current in our 1.5KW station (see case history
>> below).
>>
>> If you want to use your own coax you can get up to 7 turns of cable thru
>> the center of the toroids increasing the choking impedance even more (up
>> to
>> 10K).
>>
>> Case History:
>>
>> I run an 80 meter loop antenna about 30 feet in height and have previously
>> been using a coaxial balun common mode choke of 25 turns of RG-213 on a 6
>> inch form attached about 6 feet under the corner feed point of the loop
>> (configured in a triangle). Using a Dentron 3000 antenna tuner I was able
>> to tune all the ham bands and the lowest SWR was about 1.4 on most bands.
>> The antenna feed line was led away from the corner of the loop and was not
>> under the loop. Feed line length was about 105 feet as measured on the Aim
>> 470-TDR.
>>
>> I first placed a Super Choker™ at the antenna tuner leaving the coaxial
>> balun in place. As I retuned the antenna tuner, the first thing I noticed
>> was that I could now tune down to 1.1:1 on 80, 40 and 20 meters and I
>> could
>> not do that before. The noise level which had been running about S7 on 40
>> meters during the day had dropped to about S6 on my TS-870 receiver. I was
>> pleased that the reflected power was now almost nil and the noise level
>> was
>> lower.
>>
>> I then took the next step and replaced the coaxial balun with another
>> Super
>> Choker™. The antenna tuning was about the same but now the SWR was 1.0:1
>> on
>> 160-10 meters and the noise level on 40 was down to S5. I tuned up on 20,
>> 15 and 10 meters and worked a couple of JA’s and noticed that the noise
>> level on 10 and 15 was not even S1 – something I had not experienced
>> before
>> on the 5 acre plot of land we call home.
>>
>> What a welcome relief to find such a simple solution to RF feedback I had
>> experienced and I got a lower noise level to boot!
>>
>> These kits are all NEW production kits under the new management of Palomar
>> Engineers.
>>
>> 73
>>
>> David
>> N1EA
>> _______________________________________________
>> 600MRG mailing list
>> 600MRG at w7ekb.com
>> http://w7ekb.com/mailman/listinfo/600mrg_w7ekb.com
>>
>>
>> -----
>> No virus found in this message.
>> Checked by AVG - www.avg.com
>> Version: 2014.0.4335 / Virus Database: 3705/7115 - Release Date: 02/21/14
>>
>>
>