Message-id: <DDBC61AE1A424C76A49F7831A7BAAF79@MichaelSappPC>
From: "Michael Sapp" <wa3tts@verizon.net>
To: <rsgb_lf_group@blacksheep.org>
References: <14333894.20150720161829@chriswilson.tv>
 <776311A518F6F642962EC561A9184090D70A6C8546@THSONEP02CMB01P.one-02-priv.grp>
 <30535ED00C1845BBAF70128484243EA6@Clemens0811>
 <236241026.20150803084513@chriswilson.tv>
In-reply-to: <236241026.20150803084513@chriswilson.tv>
Date: Mon, 03 Aug 2015 10:29:12 -0400
MIME-version: 1.0
Subject: Re: LF: RE: RE: Power monitoring at LF?
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Status: O

Chris, Clemens, & All:  Last winter I ran a test on the Elecraft CP-1 
directional coupler. This is an Elecraft Mini Kit.  I had originally built 
one of these units with 31 turn type 43 cores, for
30dB coupling factor that Elecraft rates down to 1MHz and 100W power 
handling.  I changed the core material to type 75 and kept the 31 Turns. The 
result was the CP-1 re-fitted with 75 core materials kept it's 30dB coupling 
ratio down to about 50 kHz as per measurements with my HP selective level 
meter, although the return loss numbers seemed to show 100kHz or so as a 
useful measuring limit for return loss.  It allowed me to measure the return 
loss on my LF/MF EWE antenna with my HP selective level meter. Same for my 
low pass BCB filter....

 I'm not sure what kind of power limit the modified CP-1 can handle at 
LF/MF. Perhaps someone out there with an LF/MF transmitter and a CP-1 could 
modify one with type 75 ferrite cores and let us know the results... I can 
only RX below 160m ....

Test results in the dropbox link below were with the HP selective level 
meter.  I did not have precision loads for RL testing and the CP-1 uses 5 
percent load resistors. Going to .1%  or 1% load resistors in the CP-1 would 
certainly be an improvement....

https://www.dropbox.com/s/59ihr53r889td7u/Elecraft%20CP1%20Mod.doc?dl=0

If the dropbox link does not work, send me an e-mail and I will reply with a 
file attachment....

73, Mike wa3tts

----- Original Message ----- 
From: "Chris Wilson" <chris@chriswilson.tv>
To: "Clemens Paul" <rsgb_lf_group@blacksheep.org>
Sent: Monday, August 03, 2015 3:45 AM
Subject: Re: LF: RE: RE: Power monitoring at LF?


> Hello Clemens,
>
> Tuesday, July 21, 2015
>
>
> >>There are some that go down to 200kHz but these are for the
>>>'high sensitivity' 4410 range (just looks like a 43)  which
>>>implies they might need a bit of power ......  borne out by
>>>the power range going to 10kW :)
>
>> Indeed there is one element from 0.2-0.535 MHz (power range from 10W to 
>> 10kW full scale)
>> but only for the 4410 Model.One element covers 7 power ranges.
>> The elements fo the Bird 4410 Model are not compatible with the 43 
>> Model,however.
>> The  4410 Wattmeter is quite rare to find and much more expensive than 
>> the
>> much more common 43 Model.
>
>> 73
>> Clemens
>> DL4RAJ
>
> Thanks  Clemens,  and  all  those  who  replied. I'm investigating the
> LP100A  as  it seems a very useful piece of kit, generally, as well as
> being available for 136kHz. Much appreciated.
>
>
>
>
>
> -- 
> Best regards,
> Chris                            mailto:chris@chriswilson.tv
>
>