Posts Tagged ‘Antenna projects’

SWR up’s and down’s

LP-100 reading
I was on the air the other day using the MFJ loop and as I was trying to tune to the lowest SWR reading I noticed an odd thing happening! Available to me at the station are 3 separate points to view the SWR. I have the SWR reading on the K3, the LP-100 and the MFJ remote control for the loop antenna. While tuning the loop antenna I was able to get an SWR of 1.5.1 on 20m with the K3's meter this is a very decent reading. I had the same reading on the MFJ remote unit but the LP-100 was showing 2.08 SWR??? The way the meters read the SWR are as follows.....the K3 right at the radio, then the LP-100 and then the MFJ remote unit. Oh and in case you are wondering if I am SWR meter crazy, I have the LP-100 in the game plan as it also reads very accurate output power and when operating QRPp it comes in very handy. . as for the MFJ remote that just comes with the antenna package and is really used to adjust the antenna and I really don't rely on it's SWR meter. I have heard and read in the past that the remote MFJ meter should not be relied on to much. ANYWAY.............I am getting this odd reading on the LP-100 and it is on all bands that I get a differing reading from the other SWR meters. First thing that came to mind was faulty coax or faulty
K3 meter
LP-100. I bypassed the LP-100 ( I removed the LP-100 and attached the two PL-259 using a SO-259 coupling) using all the same coax that fed the LP-100 and there was no problem. I then setup the LP-100 on it's own, meaning out the K3 through the LP-100 into a dummy load and there was a perfect match. Then I simply removed the SO-259 coupling and added the LP-100 again....there was the funny SWR again. Not sure what is going on here. In my trouble shooting I tried the LP-100 on it's own into a dummy load and it worked fine. I then used all the same coax cables and bypassing the LP- 100 and all was fine. Therefore LP-100 is fine and cables are good??? Not sure what is going on here.

Final repairs on MFJ loop

Time to repair the control box.
It seems that almost all the bugs have been ironed out with the MFJ 1788 loop antenna. I sure have had an adventure with the unit but things seem to be on the upswing now. Some of the indicators the MFJ loop gives you when your match is good are High noise level meaning you are in the ball park. The SWR meters on the control box that visually tell you the SWR is good. Finally there is a tone that comes from within the control box when you are auto tuning the loop. As far as I am concerned this tone is only within the range of our cat Oliver's hearing. UNTIL........one day when I was tuning the loop in auto mode and all was going well until Julie tapped me on the headphones saying "can you not hear that ANNOYING sound!! I took my headphones off and still nothing it was not until I put my ear right up to the MFJ control box could I hear the tone. WOW my hearing must be way off  as Julie said it was very noticeable to her in the living room and to add insult to injury she also heard it over the TV. Needless to say this event happened a few more times and
Ready to remove switch
it seemed apparent that it was time to cut the wires to this speaker. While I was in there I also had to replace a switch that controls the range of the watt meter on the MFJ control head. The original switch did not work very well at all and MFJ was kind enough to send me 3 extra ones. Cutting the wires to the speaker (I could never hear) was very fast and easy but for this switch to be changed most of the unit would have to be taken apart it seemed. Once I was ready to remove the old switch and replace it with the new one it was very easy........having said "easy" it means that with the right tools it was easy. I used the Hakko 808 de-soldering gun and believe me this unit makes very easy work of removing the old solder. To the point were the defective switch just falls out of the board. In the past I have used the hand held de-soldering pumps and the wicks as well but nothing works as well as this unit. The solder station I have is the Weller WES 51 and it has served me well for many years and you can change out the tips for various jobs you want to do. So with the wires cut to the speaker and the new switch installed it's now time to just operate and no more (I hope) fooling around with the antenna.
A great tool to have

The MFJ 1788 loop arrives!

Ready for inspection
The MFJ 1788 antenna has arrived I ended up ordering it from DX Engineering and cancelling the order at the local ham store. DX Engineering had the antenna in stock were as the local store was not able to tell me when the antenna would be in….it seemed to be a waiting game. Once ordering the antenna DX Engineering had it at my door in 3 days! I can't say enough about the great service that was provided by DX Engineering. Now having said that……..I have been doing a lot of online reading about 1788 loop and how over and
Capacitor
Control box test
over again they arrived damaged or just not working. Looking at the loop it seemed to be in great shape and externally survived the trip ok. As I looked at the control unit I found one of the  push buttons not working! The  range button that changes the meter from low to the high wattage scale . I opened the control box as I also heard some "rattling" noise from within the unit as well. I found the switch to be defective and in need of changing, the rattling noise was from the battery holder. It was only held in place with two-side tape and as you guess it….there was no holding left on the tape. At this point I had a choice to make:
1. Send the control box back to either MFJ or DX Engineering for repairs?
2. Ask MFJ if it's possible to make the repair myself if they were to send me the part?
I settled on option 2 as I could still use the control box until the switch arrived and not be put on hold until control box was repaired or replaced. (note: I purchased DX Engineering's last unit)
Stepper motor
The control box failed the QC check it was now time to open up the antenna (a must according to magnetic loop user group) The visual inspection looked very good now time to power up the antenna with the control box. With the cover still off the 1788 loop I wanted to make sure the internal capacitor moved freely and stopped when full rotation was reached in both directions.
All was going well until the capacitor was rotating counter clockwise and it just stopped! I then rotated the capacitor in the clockwise direction and back counter clockwise and it worked just fine. After many back and forth rotations the capacitor never acted up…..maybe this was a one off. I emailed MFJ regarding the switch and they are going to mail one to me so I can do the repair. Next is to mount the antenna and see how it performs stay tuned!

The reverse beacon network is KILLING ME!!!!!

The loop horizontal and nothing. 
In my last post I wrote about how my Alexloop was just not getting out in the condo, I was checking the Reverse Beacon Network as I called CQ at 5 watts from my condo and there was ZERO spots! Well from that post I received lots of great suggestions on how to get VE3WDM's signal from the antenna to the world. So here is what I tried........I mounted the Alexloop in the horizontal position in the condo and it netted no spots on the Reverse Beacon Network. I then put the Alexloop on the balcony seeing that we are 60 feet in the air I felt this was a sure thing. The last option for me was to place an antenna on the balcony as it was open season to the condo cops.  I placed (in the cover of darkness) the Alexloop on the balcony and called CQ on 20m and 40m and then check the Reverse Beacon Network. To my surprise there were no spots and now I am really stumped and frustrated. The Alexloop is out in the open 60 feet in the air and no spots what the heck is going on......do those dam condo cops have ham radio jammers!!!!!! Up to this point I have only use the RBN to check for spots but there is also WSPR and I have had some bloggers suggest I use this. At this point I am not able to get WSPR up and running as there seems to be some software issues. My goal now is to sort out the issues and give WSPR a go both with the Alexloop in the condo and out on the balcony. This coming weekend I hope to get on the air with WSPR and give that a go! Im really not frustrated I see this as a challenge, for me to get ham radio on the air from a condo will but only  help others in the same situation as me get on the air.

A trip into the attic.

Alpha Delta DX-EE with balun.
Hy-gain noise antenna
Being in an antenna restricted community.....now when I say restricted it is in the most extreme way. We have what I call the "condo cops" they do a walk around at least once a month to make sure all is well. If I ever even had a temporary antenna up I would be under their watchful eye!! In a way it's kinda comical it's like these folks on the board have nothing else better to do with their time.....maybe they should get a hobby. Anyway it was time for me to head up to the attic to check on the antenna farm. It has been cool these last few days which makes the attic a bit more bare-able. I have done some reading and it seems the attics in the States have A.C. units, furnaces and even plumbing. Up this way it's great for antennas as there is nothing other than electrical wiring (which can have it's own challenges). I always like to see how the Alpha Delta DX-EE is looking making sure the supports are secure and in good shape. I was good to see the center support rope is in good shape along with the support ropes at each end of the dipole as well.  I did notice one of the 40m traps was sagging a bit......BUT......as they say "if it's not broke don't fix it" Goodness knows if I tightened up that leg (just for my piece of mind only) Murphy could have a hay day with me!!
H-900 active antenna
The antenna looked fantastic other than the sagging I mentioned.....but they say that comes with age!! Anyway I did want to make a minor change for the antenna. I wanted to add a 1:1 balun at the antenna to improve the coax isolation. I have used Balun Designs baluns for all my attic antennas and they are very good quality and super support. Before making any changes I used my trusty MFJ-259B antenna analyzer to check all the bands SWR. I wanted to see if adding the balun changed the SWR at all. I did find that the SWR did go up on some bands and down on other after the balun was in place. It was a very insignificant change in either direction. The other antennas that I have in the attic is an old Hy-gain 18TD portable dipole  that winds in and out like a fishing line and can be set to individual bands. It's similar to  a measuring tape so you can set it for the wave length of the band you want to use. I use this antenna as a "noise" antenna, the MFJ-1026 needs to have a separate noise antenna for the unit to work. The unit does come with it's own telescoping antenna but I did not want to have that antenna extending in my shack. I also have another antenna with is the LF engineering H-900 active antenna. I use this in conjunction with my Elecraft K3, it is the antenna for the sub-receiver. As a side note I just was looking up the Hy-gain 18TD antenna to provide a link......came across someone who sold this antenna on Ebay for almost 500.00!!! Are they going for this much???? If so I can part with it and raise a another noise antenna!
Sagging 40m trap

Setting up for some morning radio time


The car with the mono band 30m whip
I have been reading on some blogs how op's have been able to fit in some operating time during lunch hours and been successful at making some contacts. For me lunch time is not an option as I am out and about during the day and no where near my car at the lunch hour....BUT.....I do get into work about an hour or so early and that would be my ideal radio time. I would be operating from around 5:30a.m. for an hour or so. I feel that either 40m or 30m would be my best bet around that time. When in my mobile I use mono band
The mount

Final SWR on 40m
whip antennas. To prepare for my morning mobile operating time I had to tune both my 40m and 30m whip antennas. I took with me my trusty MFJ antenna analyzer and this thing is great as I find I can tune a whip antenna to the lowest SWR on a desired frequency in about 10 minutes.  With the size of my car being very very small (Scion IQ) the ground plane is very small. For this reason I was only able to tune both antennas down to about 2.2.1 and 2.3.1. Thats ok as I do have in the KX3 an antenna tuner that will make the rig see a flat match. It was a nice sunny day with perfect temp's as well for this little project. When I was done and starting to pack up a gentleman came up to me and introduced himself. He saw my license plate (VE3WDM) and connected that call to my blog. He was a ham as well and a reader of my blog.....kinda cool. We had a nice conversation for about 15 minutes exchanging ham talk and he had to get back to eating his lunch and heading back to his job. (as for me I had the day off) I am hoping if the weather is good this coming week that I will get my CW out on 30 and 40m in the early mornings.
Final SWR on 30m

Alexloop vs Attic dipole

Setup for test. (Laptop running Ubuntu update)
The propagation conditions have not been all that great over the last couple of days so what a better time to do some on air Alexloop vs attic dipole comparisons! Here is the setup I used my Elecraft K3 putting the Alexloop in antenna 1 on the K3 and left the dipole on antenna 2 on the K3. This way I can use the internal tuner for the dipole and remove the antenna tuner for the Alexloop with just the push of a button on the K3. The power output was 5 watts, figured I would go to the top end of QRP considering the atmospheric conditions being not so hot. The Alexloop was up in my radio room facing West out the widow and East through my house walls. The Dipole is in a "Z" configuration in the attic so it kinda is facing most all directions. The Alexloop frequency was 14.061 and the dipole was 14.059 and I was using CW along side the Reverse Beacon network. The current atmosphiric conditions at the time of the test were:
A-5
K3
SFI 157
SN 173
Below is the results of the test.....not so well it would seem the Alexloop netted zero and the dipole only one. So is seems for a more acurate comparison better conditions are needed.


Subscribe FREE to AmateurRadio.com's
Amateur Radio Newsletter

 
We never share your e-mail address.

Please support our generous sponsors who make AmateurRadio.com possible:

KB3IFH QSL Cards

Hip Ham Shirts

Georgia Copper
Expert Linears

morseDX

Ni4L Antennas

Ham-Cram
R&L Electronics

Do you like to write?
Interesting project to share?
Helpful tips and ideas for other hams?

Submit an article and we will review it for publication on AmateurRadio.com!

Have a ham radio product or service?
Consider advertising on our site.

Are you a reporter covering ham radio?
Find ham radio experts for your story.

How to Set Up a Ham Radio Blog
Get started in less than 15 minutes!


  • Matt W1MST, Managing Editor




Sign up for our free
Amateur Radio Newsletter

Enter your e-mail address: