Small Receive Loop Installation

 I'm just wrapping up the latest antenna farm project with the addition of an active receive-only loop.   This came out of a need to improve my lower HF bands receive capability and help deal with local manmade noise in the neighborhood.  The antenna + preamp combination I chose is the DX Engineering Pro-1B.

The system is located about 250' behind the house in the woods -- away from noise sources and neighbors. The antenna is ground mounted on about 10 feet of electrical conduit, with 2 feet of the mast embedded in a concrete filled hole about 8" across.   To rotate the loop, a Yaesu G-450ADC light duty rotor with the optional mast mount kit is installed about 3' from the bottom of the loop.   Belden 75 ohm quad shield coax carries the RF from the preamp as well as DC to power the preamp.   The Yaesu rotor requires (4) 18 gauge wires, and I found  "outdoor" 4 wire speaker cable (eBay) does the trick economically.

To combat any common mode noise finding its way into the preamp / antenna -- I wrapped several feet of coax (about 8 turns) on a mix 31 ferrite toroid just before the feed line connects to the output of the preamplifier.   All coax and control connections are sealed with layers of Scotch 33+ electrical tape followed by Scotchkote.  (This weatherproofing method has been successful here -- I've just unwrapped connections sealed this way from 21 years ago and they are still pristine.  It takes extra time and can be messy...but well worth it.)

My initial impressions are very positive given that summertime isn't exactly "quiet" on the lower bands.  I'm testing it with an RSP-Duo SDR, and although signal levels are lower than what I'm used to on other wire antennas, the noise levels have fallen more than the signals ==> hence, a better SNR.   These bands have never sounded so clean, and should I see any noise (and I do from some SMPS next door) -- the loop will null that noise out when broadside to the noise source.   So far, so good.

Pro-1B Loop Antenna & Preamp

Mix 31 Toroid at Preamp

Fripp Island, SC

 Operating portable is something I increasingly enjoy since I bought the Elecraft KX3 at Dayton a few years ago.  Whenever I go somewhere for more than a few days and in a location where I can throw up a wire antenna, I'll pack the rig and accessories and make something happen.   For the family vacation this year, we're able to visit Fripp Island (IOTA NA-110) in South Carolina and rent a cottage on the southern tip of the island near Skull Inlet with a view of Pritchards Island.   Beautiful spot with more than a 180 degree view of salt water!

I used the 31' Jackite fiberglass mast and mounted it with bungee cords to the ramp leading out to the Atlantic Ocean.   The antenna is simply a 29' wire taped to the mast, fed at the base with a "QRP Guys" UnUn;  I added three radials to the base, slightly elevated.   With the tiny VNA I was able to see decent matches at the end of the feedline on several bands -- and the KX3 ATU loaded 40, 30, 20, 15 and 10 without much issue.  I'm sure I had some significant feedline loss on the 50' of RG8X, but was able to make a bunch of CW contacts despite the lousy solar conditions, on anywhere from 5w to 15w.   Lots of fun!

 With all the "fun" I've been having at the home QTH with RFI -- I was hoping this location was going to be super quiet.  I was honestly surprised to see that it is noiser than home.  Even after turning off the main breaker on the cottage, I saw/heard major power supply noise (S5 to S9) on 40m and 20m obliterating large chunks of the bands; no doubt the vertical enhanced pickup of noise (despite a common mode choke on my feedline), but with the low housing density here...I didn't expect it.   

My PX3 panadapter has been flaky since purchase, and I found some time over this week to take it apart, inspect the build, find the problem, and fix it.   The display had only been illuminating with green -- whereas it should be vibrant blue, yellow, green, etc..  Turns out the ribbon cable from the main board to the display was not properly connected to the board connector;  it's a delicate cable, and needs some real care getting it properly seated.   Once fixed, the PX3 became MUCH more useful -- and I'm delighted with its performance.   Seeing the signals and the noise really adds a very positive dimension to amateur radio...I'm spoiled now to the point that it would be hard to go back pre-SDR days.

Tonight is our last evening, so I'll see about working a little grey-line DX on 30m tonight before I tear things down.   

de W4QA/p