[Elecraft] [K3] MFJ-1786 Antenna

[Kurt Pawlikowski]

Dave,

     I recently purchased a used 40-15 meter version (MFJ-1788). I live 
in a first floor condo and really have no place to permanently mount it, 
so I use it on either a short 3 foot stand or extend it to 10 feet with 
my car stabilizing the base. I've had this antenna for about 6 months 
now. So, here are my impressions...

      First, if you like to jump around the band or bands, don't be in 
too much of a hurry! It takes a little while to get used to operating 
the antenna. While it's not too bad, you can't just spin the dial and 
start transmitting. The practical bandwidth of the antenna on 40 meters 
is about 10 kHz. You can receive degraded signals to maybe 30 kHz, but 
they get weaker and weaker the further you are from the currently tuned 
frequency. The bandwidth seems to get narrower as the frequency 
increases. This is just the "nature of the beast."

     Performance is very good. It appears to be on par with a full 
dipole, but I don't have one to compare it to, so it's all subjective. 
And, since my installation is very low (3 or 10 feet), my contacts tend 
to be in the first, second or third skip zones. That is, it's probably a 
fairly high angle of radiation. I have not tried the antenna in 
"horizontal" mode, but maybe I will some time.

     In my particular case, I have a very noisy mercury vapor lamp about 
20 feet from the antenna that is dieing. When it's cycling, it 
obliterates most of the signals with it's own 20 over 9 signal. This 
simply swamps the KX-3's noise blanker. It is for this reason that I've 
been in the market for the MFJ-1026. But, in the mean-time, I discovered 
that my Drake R4-C noise blanker virtually eliminates it. I've been 
toying with the idea of a "better" radio (K3 or Flex) that might have 
enough processing power to nullify the noise. Of course, that's a 
financial consideration!

     At any rate, it means that, between tuning up the Drake R4-C, TX-4C 
AND the MFJ-1788, it takes me several minutes to adjust to any new 
frequency. Once I get in the sweet-spot, I'm not too likely to go very 
far from where I am. Yes, using the KX-3 (during the day!) works well, 
but you need to keep the ATU off as it defeats tuning the antenna. I 
have even used this antenna sitting on the ground surrounded by metal 
shelves and a parked car with a fair amount of success. Again, I have no 
basis for comparison, so no objective data.

     Well, I hope that helps!

     kurtt

     WB9FMC
     2015 Hamfesters Hamfest Chairman
     Looking for my replacement since 2014!
     http:\\ham-ham.org

On 9/6/2014 20:50, David Guernsey via Elecraft wrote:
> Does anyone have any experience using a MFJ-1786 with a K3? I live in a 2nd floor condo in a 5 story brick building. Considering a magnetic loop on my balcony to get back up on HF.
>   
> 73 de Dave KJ6CBS
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