K9AY Receiving Loop Antenna

I have an acre lot and that sounds like a pretty good size, but actually space for antennas is at a premium. The the house sits fairly far back on the lot and the lot is fairly long and narrow, almost a pie slice shaped, coming to a point in the backyard. Further complicating the issue is the arrangement of the trees that make for little room for low band antennas. I was able to squeeze a 40 Meter Double Extended Zepp fed with open wire feeders. Even in an Inverted VEE configuration it goes from lot line to lot line. It does a very good job on most bands, particularly 10 Mhz and below, I generally get pretty good signal reports but the antenna is noisy.

Non-resonant antennas tend to be noisier than resonant antennas, and dipoles tend to be noisier than loops, at least in my experience.  This antenna confirms my experience.

K9AY Loop May Be the Answer

I have been looking for a good solution to the noise problem on receive and had heard about the K9AY loop antenna. It is a relatively small receiving loop that works well from 10 Mhz and down. I talked to with several hams about their experiences with the K9AY. N4IQ, Bill, is South Carolina was a great source. He has the K9AY and several beverage receiving antenna and had high praise for the performance of the K9AY.

When I saw a Array Solutions K9AY loop controller on QRZ’s swap page, I jumped on it. I had the controller in a week and started collecting the other bits and pieces for the loop. I measured off a space in one of the pine straw islands in the back yard.  I found a good place to put it, but need to get some professional clean up of trees and low limbs.  After the clean up the XYL was pleased with the  the yard too. Little did she know what was coming!

What is a K9AY loop and why did I want one?  The K9AY is a receiving loop antenna that works well on the lower frequency bands.  It resembles a Delta Loop, but is a very good directional receiving antenna.  Comprised of a 85 foot loop with a switching box located at the bottom feed point.  Below is the basic K9AY Loop.  You can click on the photos for a larger view:

Basic K9AY Loop Configuration

The loop is supported at the top, usually by a fiberglass pole, and fed at the bottom.  One side of the loop is coupled to the feed line with an impedance matching transformer and the other side of the loop is returned to ground through a terminating resistor.  This makes the loop directional in the direction of the feed line side, somewhat like a Beverage antenna.  The K9AY now produced by Array Solutions, there are two loops, set at 90 degrees from each other and a control box with relays switches the feed and termination side of the loops.

Setting the corners of the loops to the NW, SW, NE, NW directions and using the control box to select the proper feed and terminations gives a 4 directional antenna.  The relays are controlled by a controller in the shack, that also includes a preamp.  Since this is a small loop, there is a bit of loss of signal strength.  The preamp helps bring the signals back up to about the same as a large antenna.

Array Solutions K9AY Loop Control

My K9AY Loop

My implementation was to hang the top of the Loop from rope at strung between two trees in the pine straw island and then tie off the ends to stakes in the ground.  At the feed point of the antenna there is a relay box.  The relay box is a waterproof 4 inch electrical box with a plate attached that allows it to be mounted to a round post using a U-Bolt.  I used a 30 inch section of 1 inch galvanized water pipe driven into the ground for the relay box mount.  I made a strain relief / insulator for the loops out of a piece of 1/4″ PVC sheet.  I cut a hole in the center that it would fit over the 1 inch pipe, and used a hose clamp below and a pipe cap on top of the PVC sheet.  I drilled 4 snug holes in the corners to bring the loop wires through and wrapped them down to the relay box.  I drove a 8 ft. ground rod beside the mounting post and tied the ground connection to the rod.

K9AY Base Detail Photo

To hold the top of the loop I made an insulator out of a small piece of PVC pipe with three sets of holes drilled through it.  The top hole is for the support rope, another pair holes for the SW/NE loop to go through the insulator, and another pair of holes at 90 degrees from the first set for the NW/SE loop.

Top Insulator Detail

Finally, to hold then ends I used simple dog bone antenna insulator tied off to the ground stakes.

Dog Bone corner insulator

Ok, the ground stakes didn’t work all that well.  Because the stakes were too close in from the center of the loop, the ends of the loop were too low.  I just happened to have 4 trees that were off the ends of the loops, so I used some 1/8 inch rope around the trees at about 36 inches above the ground. That brought up the ends of the loops to a good height.  It is hard to see, but in this photo looking across a loop, you can see the ends tied off to the trees.

Loop End View

Not that I was actually trying to hide this antenna, but with the black top rope and the black insulated wire for the loops the stuck back in the trees, the antenna is just about invisible from the yard.  You can see the insulators and the florescent orange tie ropes for the ends, but otherwise it is very hard to see.  If you are in a place that you have to hide your antennas, this arrangement will work great for a hidden antenna.

Results

I have had a few days now to work with the antenna.  I love it!  For some reason it is very noisy at my QTH.  This antenna drops the noise level about 15 dB on 40 meters.  My day for NCS on the Sunrise CW net gives me a good opportunity to evaluate the antenna.  I can hear stations much better, and using the directionality of the antenna to reduce the noise and QRM I can copy stations much better than with the vertical or my Zepp.

I find that the loops pattern is a very broad front lobe with a very sharp notch off the back of the antenna.  It works better at notching out a signal off the back of the antenna than bringing up a signal off the front.  However, it still works very well.  As you might expect, it doesn’t do much for very strong signals, other than notching them down off the back, but it will bring the noise down and the signal up on weak signals and make them very easy copy.

It works well on 160 meters through 40 meters, although the preamp in the Array Solution control box passband is about 1.5 to 4.5 Mhz, using it on 40 without the preamp works just fine.  It also works very well on the AM broadcast band.  I like listening to AM DX and this antenna works well.  I have seen several instances when listening on US Clear Channel stations that I can switch the antenna to the SW or SE and completely notch out a US station and hear a Caribbean or Mexican station 599.

What now?

Well, other than wearing out the direction selector switch playing with the antenna, I have read that ground radials under the Loop Array improves the performance.  So I will be getting some wire and put some radials under the array to see how that affects the performance.

Update

I recorded audio from the FT-1000MP on 40 meters switching between the K9AY loop and the inverted Vee antenna.  From the recording you can hear the superior signal to noise ratio on on the K9AY compared to the Vee.  The preamp in the Array Solutions control doesn’t cover 40 meters, so the signal strength drops a little, but the Signal to Noise ratio is still superior on the K9AY loop.

TRAM 1480 Dual Band Antenna

I was looking for an inexpensive dual band VHF/UHF antenna to use with my go box radios.  I came across a dual band antenna from TRAM on Amazon that was half the price of similar Diamond and Comet dual band antennas.

The specs for the Tram were advertised as follows:

Gain:                                    6 dB on 2m or 8 dB on 70 cm

VSWR:                                Less than 1.5:1

Frequency Range:             144-148 Mhz and 430-450 Mhz

Polarization:                      Vertical

Impedance:                        50 Ohm

Configuration:                   5/8 Wave 2 Element (2m) and 5/8 Wave 4 Element (70cm)

Power Capacity:               200 Watts

Connector:                         UHF Female

So I ordered one and in a few days I had it in hand.  It was 48 bucks and it was free shipping.  Not a bad price at all.

The antenna was packaged nicely and arrived in good condition.  The antenna was shipped in two pieces that were less than 54 inches long.  Assembled the antenna is just over 8 ft. at 98 inches long.  (Click on the thumbnails to enlarge the photo)

tramdualband-1

The antenna is very similar in design to the Comet antennas and uses the same mounting system as the Comet antenna with a aluminum sleeve at the bottom of the mount with extruded aluminum brackets and stainless steel U-bolts.  It was all neatly packaged and all the parts were there.

tramdualband-2The antenna requires assembling the two sections using a Allen setscrew.  The required Allen wrenches are supplied with the antenna and the assembly is very easy.  With a pair of needle nose pliers you pull the center radiator out of the top section and connect it to the pin on the bottom section.

The two sections are shown here, the bottom on the right and the top on the left.

tramdualband-3

Shown here with the two sections joined with the setscrew.

tramdualband-4

Then slide the innards back into the antenna and tighten the coupling nut that seals the two halves of the antenna.

tramdualband-5

Then add the radials, the mounting sleeve, and clamps and attach it to your mast.

tramdualband-6

The TRAM Dual Band Antenna assembled and ready for SWR testing.

I mounted the antenna on a tripod and attached a 50 ohm coax cable and the MFJ Antenna Analyser.  Below is the VSWR I measured at several frequencies across the bands:

Frequency SWR Note
144.0 2.3:1
144.5 2.1:1
145.0 1.8:1
145.5 1.6:1
146.0 1.4:1
146.5 1.3:1
147.0 1.3:1
147.5 1.2:1 Low SWR @ 147.4 mhz
148.0 1.3

 

Frequency SWR Note
440 1.4:1
441 1.3:1 Low SWR @ 441.4 mhz
442 1.4:1
443 1.5:1
444 1.5:1
445 1.6:1
446 1.7:1
447 1.7:1
448 1.7:1
449 1.7:1
450 1.6:1

Well, so much for the VSWR Spec!  The SWR reads a bit high on the MFJ.  The FM portion of the 2 meter band seems to be pretty useable and the lower section of the UHF where one transmits seems to be usable.  In a functional test with a FT-8900 there was no problems.  I could hit the repeaters just find and I could get into the 2 Meter packet nodes with no problem.  The rig didn’t show any issues with the antenna and it performed nicely.

All in all, not a bad antenna for 48 bucks.

Staggering Numbers

This past Presidential election is best explanation of why the Founders had unbelievable wisdom in designing the Electoral College.  From listening to the discourse it seems that most people think the US is a democracy.  However, cupcake, it is in fact a Republic, i.e. the “United States of America.”  In a Democracy the popular vote would be the way you would elect the leadership of the country.  In a Republic of states, the states elect the leadership of the county.  Us older folks were taught this stuff in schools, but I am not sure that kids today get the same education that we got!  The founding Fathers recognized that if straight popular vote elected the President the vote would be completely influenced by a few large cities on east coast.  (nothing much has changed there!)

It also illustrates that the Democratic Party does not represent the country, just the heavily populated east and west coast mega cities which are out of touch with the vast majority of the country.

Here are the numbers:
There are 3,141 counties in the United States.
Trump won 3,084 of them.
Clinton won 57.
**********************************
There are 62 counties in New York State.
Trump won 46 of them.
Clinton won 16.
**********************************
Clinton won the popular vote by approx. 2. million + votes.
In the 5 counties that encompass NYC, (Bronx, Brooklyn, Manhattan, Richmond & Queens) Clinton received well over 2 million more votes than Trump. (Clinton only won 4 of these counties, Trump won Richmond) Therefore, these 5 counties alone more than accounted for Clinton winning the popular vote of the entire country. These 5 counties comprise 319 square miles. The United States is comprised of 3, 797,000 square miles.

When you have a country that encompasses almost 4 million square miles of territory, it would be ludicrous to even suggest that the vote of those that encompass a mere 319 square miles should dictate the outcome of a national election.

When you look at the number of counties won by each of the candidates you can see that Trump’s win was in fact a landslide victory.

Vintage Radios and Modern Headphones

I have a number of  pieces of “Vintage” Amateur Radio equipment that I have collected, repaired, and use regularly on the air.  A lot of my time on the air is on CW, or Morse code for the non ham readers out there, and I use headphones to copy weak CW signals from time to time.   Vintage headphones are not particularly comfortable to use and are hard to find and every harder to restore.  So I wind up buying modern stereo headphones to use on my newer equipment and also on these older tube type radios. That creates a problem.  These older radios are not the quietest things you want to hook to a pair of stereo headphones that have a wide frequency response.  There is high frequency hiss noises created in the tube circuits and 120 Hz hum from the unregulated power supplies.  Where modern amateur radio equipment has electronically regulated power supplies providing ripple free voltage for the circuits these older radios typically have a transformer with a full wave rectifier and high voltage filter capacitors to try to remove the ripple from the power that feeds the audio circuits.    That produces a small amount of hum in the speaker that becomes not so small when you connect a set of headphones to the radio.  So, what has that got to do with stereo headphones?  Well, first off they are stereo.  The older radios are all monaural, so some sort of plug in adapter is required to bridge right and left channels of the stereo phones to the monaural radio.  Second, there there is the hiss and hum, particularly the hum being a problem for me.  Modern stereo headphones are designed for very flat frequency response from below 50 Hz to 20,000 Khz.  I don’t want to be hearing all that directly coupled 120 Hz hum from my Drake 2-B into my new Koss headphones!

I hit upon the idea of putting a small audio passband filter in a 1/4 phone plug and build a passive filter for this application.  I cracked the books on basic filter design and came up with this circuit:

outputfinal

Click on the graphic to see a larger image

A passband filter is comprised of a Low Pass Filter and a High Pass Filter in series between the input side and the output side.  In this case I selected a low cutoff frequency of 400 Hz and a high cutoff frequency of 900 Hz.   I usually tune in CW signals at around 600 to 700 Hz so that makes the filter just right for CW work.  Since these are R (resistance) and C (capacitance) filters, I wanted to keep the resistor values low in this low impedance circuit to keep the loss of signal down.  Using the formula:

formula

I selected 27 ohm resistors and calculated the capacitor values and then rounded them to standard values that I had in my parts box to get the circuit shown above.  The caps came out to be 6.5 microfarads for the Low Pass Filter and 15 microfarads for the High Pass Filter.

Not only did I want filter the audio I needed to convert from the typical 1/4″ Headphone jack that was used back in the day to a 1/8″ Tip/Ring/Shield that is commonly used on modern headphones.  I hit my local Radio Shack’s parts drawers and found a very old school 1/4″ plug that had a big fat pull handle on it.  It would give me plenty of room for my R/C components inside.  I did a bit of trimming on the ground side of the plug to give me a bit more room for the components, and everything fit nicely into the handle.  Here are a couple of pictures of the results:

Finished Filter Adaptor

Finished Filter Adaptor

Components

Assembled Components

The results were quite good.  The hiss and hum is reduced by a considerable level making the copy of weak CW signals much better and reduces my fatigue by not having to listen to quite loud hum through the headphones.  All in all it was worth while project for a afternoon where it was too hot to do much outside!

RMS Express and the PK232

RMS Express is a program for sending Email via Amateur Radio via the Winlink network.  It has capability of sending Email over the internet, over a High Frequency (HF) radio link, or over a Very High Frequency (VHF) radio link via AX.25 Packet Radio.  This program is used by many of the hams that are in the Amateur Radio Emergency Service to send and receive Email messages while deployed in emergency situations.  The program works well, and its operation is almost automatic.  On HF it will use propagation prediction software select the best frequency to contact a radio gateway to the Winlink Network and send and receive email messages.

On VHF, using a Terminal Node Controller (TNC) and a VHF-FM transceiver the program will configure the TNC settings and make a connection to a gateway and send and receive emails with little intervention by the operator.  However, once you are done with the RMS Express software, and you want to go back to sending packet radio messages to other systems or to other Ham Operators, the settings that RMS Express had set in the TNC are still there.  Some of these setting need to be changed before you can perform keyboard communications.  This required typing a half dozen or so commands into the TNC, not a big task but none the less it has to be each time you open your terminal program after you have used RMS Express.

I wanted a way to reconfigure the TNC after quitting RMS Express.  I had the bright idea to set up a batch file in Winders to send the required settings for keyboard communications to the TNC via the Serial Port.  Well, I was able to get a batch to do that, but it didn’t work well.  I tried several different approaches in my batch file but I had no success changing the TNC.  The biggest of the problems was handling the carriage returns that are required for the TNC to process commands.  Each command string needed to be terminated with a carriage return (Enter Key).

Looking around the internet I found Plink, a add on to the PUTTY terminal program that I use for Keyboard Packet communications, but it is more geared toward automatically logging into remote systems than sending commands to a TNC.  Finally, I came across a utility called SerialSend at https://batchloaf.wordpress.com/serialsend/

Serial Send is a command line utility that will configure a serial port an send a string and control characters to it.  Just what I needed to do.  If you would like to give this utility a try, download the utility from the sight above and copy the serialsend.exe file into a folder that is in the system path.  This will make sure the program can be executed from any folder on the computer.  If you don’t know what your system path is, open a command window (click the start button, select the “run” command and type ‘CMD’ and press enter.)  and type “path” at the command prompt and press Enter.

Path Command Result

Path Command Result

You can see that the C:\windows folder is in the path, and that is a good place to copy the serialsend.exe file.

Once you have the serialsend.exe file in the C:\windows folder, test the path to the file, again from your command prompt, type “serialsend” to make sure the serialsend will execute.

Screen Shot 2016-04-30 at 3.27.16 PM

serialsend result

So now we have the program loaded test with a single command to the TNC from the command line.  Type:

serialsend /baudrate 9600 /devnum 16 /hex “alfdisp on\x0d”

This should open Com Port 16 (COM16), set the baud rate to 9600, and send the TNC command ‘alfdisp’ followed by a carriage return.  I am using the /hex option of serialsend to allow the insertion of a carriage return.  (hex 0D)  ALFDISP is the command to make the TNC send a line feed character to the terminal a the end of each line sent.  Check the command by opening your terminal program and type ‘alfdisp”, the TNC should reply ALFDISP is now ON.

Having success with one line, I put a series of TNC commands into a batch file to use serialsend to setup the TNC. Here is the batch file contents:

serialsend /baudrate 9600 /devnum 16 /hex “alfdisp on\x0dacrpack on\x0dmon 4\x0dmto all\x0dmfrom all\x0decho on\x0d”
c:\Users\Bob\Desktop\putty -load PK232COM16
exit

There are three lines to the file. (note: on your screen the first line may be wrapped)  The first line invokes the serialsend utility setting the baudrate 9600 on COM16 and sending a string that contains hex coded characters.  The string is inside the quotes.  The next line starts my terminal program, PUTTY, and opens a profile named PK232COM16 with the -load command.  The last line, exit, will close the command window after the PUTTY program is closed.  Use Notepad to create the file above and save it as ‘packetsu.bat’ in your documents folder.

That’s it.  I can run RMS Express and do my emails.  Then run the ‘packetsu.bat’ and configure the TNC for keyboard communications and open the PUTTY terminal program.  Put a shortcut to the packetsu.bat file on your desktop and you can open the terminal and be ready to communicate with one click of the mouse!

 

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