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For some time now I have been trouble shooting my MFJ 1788 loop off and on. I have had a problem with getting 20m to tune. The best I could do was an SWR in and around 12 to 1 and really that is not good at all. Even with that SWR the K3 tuner was able to drop it too a flat match but odd things were still happening....for example
1. Tuning the loop for max noise (as low SWR was not happening) did happen but as soon as the rig was tuned in any way the noise dropped to nil.
2. Once max noise was achieved and I transmitted the max noise was gone again.
3. There was no spots on the Reverse Beacon Network while giving the tuned match a go.
4. When transmitting power levels were all over the place from 1 watt to 5 watts.

I had posted my 20m tuning problem on 2 loop user groups and had some great advice but nothing seemed to even come close to solving the problem. I then emailed MFJ  who very promptly emailed me back and advised me to change the shape of a 12 gauge copper loop that was located inside the loop. Easier said than done this involved removing half the plastic cover on the loop and changing the shape of this loop then

Adjusting the loop

checking the SWR. The hard part was trying to figure out where the sweet spot for 20m was on the loop  was. The loop would read an SWR of 12 to 1 no matter what adjustment I gave the loop. I ended up tuning the loop for the highest noise level I could hear. I figured this was as close as I could get to the sweet spot for 20m. Adjusting this small loop did not really change anything and I was getting frustrated! The best thing I find when this happens is to put the project aside and do some thinking. I did just that over the past few weeks I enjoyed the bands the loop would tune and thought about my next move. The loop consists of a rotating capacitor that tunes the loop via a motor. I had been reading on the loop reflector sites and a reoccurring conversation was how quality control at MFJ was very low. For some reason I wanted to check the spacing of the capacitor plates on the loop antenna . It turned out the plates had a warp to them and at the low end spacing was good but in and around

Some plates to close

20m's  some of the plates were very close and maybe touching each other. After some time of tweaking the plate spacing I was able to have equal spacing for the full rotation of the capacitor. The SWR on 20m is now down to 1.4 to 1 and that was the problem as I put the loop back together I kept an eye on the SWR to see if it changed at all. The piece of  equipment that really helped me out with this process was the MFJ 259B analyzer. This unit made tracking my SWR very easy, bottom line is the antenna is now working great and now it's time to get on the air and see how 20m is preforming from the condo.

Pumping out 1/2 a watt

On Saturday I was very pleased to see that my MFJ 1788 loop antenna was getting out. On Sunday it was time to push my luck to the limits, here are VE3WDM I always like to see how little power it take to make a contact. It seemed yesterday 5 watts most if not all the time was getting through. Why stop at 5 watts it was time to drop the Elecraft K3 below the 5 watt maker.............wayyyyy below! The conditions once again were very nice Flux levels were up along with the Sun spot count but the K index was also in around 4. That did not seem to matter the bands were full of contest action. Once again I stayed on 15m and it was very busy with DX from the contest. Today I made only 20 contacts as there was chores to get done around the house.

Hard at work

Yesterday's post concentrated on the country count and locations today's post is all about power levels and miles per watt. From 5 watts I dropped down to 2 watts to see what would happen and DK3GI was in my cross hairs. I was able to make the contact first call which gave me 2020 miles per watt. From there on out of my 20 contacts 19 were all over 1,000 miles per watt. Here is a run down:
1 contact made at 3 watts
4 contacts were made at 2 watts
7 contacts were made at 1 watt
6 contacts were made at .5 of a watt
1 contact made at .1 of a watt
1 contact made at 5 watts ( this being the only contact not netting me 1000 miles per watt)
Some of the miles per watt numbers
II9P at .5 of a watts netted me 18,470 miles per watt
K5RT at .1 of a watt netted me 11,808 miles per watt
CN2AA at .5 of a watt netted me 7682 miles per watt
F8CIL at .5 of a watt netted me 7662 miles per watt
F5NBX at .5 of a watt netted me 7608 miles per watt
CS2C at .5 of a watt and netted me 7216 miles per watt
This contest I was just a point giver and not in the contest to submit a score. I wanted to test out the MFJ 1788 antenna to see how my location and antenna performed. Some things that still have to be done, I have to get the contesting software and radio control software up and running. Have the SWR problem on 10m and 20m figured out with the MFJ 1788 loop, for some reason the best SWR I can get is around 9! On a positive side this contest proved to me that the antenna will get out even with QRP or QRPp power!!

The K3 doing it's work

I was able to get in a few hours in the ARRL CW contest this afternoon and  operated only on 15m. My output power was QRP 5 watts into my balcony mounted MFJ 1788 iso-loop. I was pleasantly surprised with the results I was able to make 40 DX contacts in 23 different countries. I was not able to make any 1,000 mile per watt contacts but I did come close at 4500 miles (using 5 watts). I found the noise floor to be just great and the EU stations were just booming in. There were some stations that did have trouble with my signal but over all exchanges were made first time.
My SWR was in around 1.4 to 1 and it was very simple to adjust the SWR as I went up and down the band. You just have to get the hang of tuning the loop and it is a simple push of the fine adjustment button and your all set to go. This evening I tried 40m and there was lots of EU stations but for some reason I was not able to make any contacts so after a short time I shut things down for the evening.
Tomorrow I am going to try to make some contacts with less than 5 watts and hopefully get some 1,000 miles per watt contacts.
Some of the highlights were:
Tunisia
Balearic Island
Finland
Alaska
Nicaragua

I had some spare time today to put the MFJ 1788 loop to the balcony test once again. Up to this point I have not been able to make any CW contacts with the antenna. I was able to pull in some State side WSPR spots but that was it. I was coming to the conclusion that my DX was going to be Canada to U.S contacts. Today I set the Loop antenna for 15m and the SWR was great at 1.1:1. and up and down the band I went. I heard KP2/AG2J calling CQ at 21.025 and he was booming in here. I called out to him and low and behold he came back to me with a fast report! Fast report or not my 5 watts signal from the balcony just made it to the Virgin islands!! I then heard KH6LC from Hawaii..........but I was not able to make contact BUT for the first time I was hearing some DX stations. I then was able to contact PJ4LS with some repeats on my part but I still had my 1788 loop signal down to the Antilles off the coast of Venezuela!! The other station I heard but was not able to contact was ZZ80MT in Brazil. This was a good afternoon on the radio of me I was able to hear and make some DX contacts.

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 MFJ 1788 is now on order.........well back order for now and was told it could be up to 4-6 weeks before the supplier see's it. I did go online and see if any U.S radio outlets have the antenna. They do but the shipping is close to 200.00 then you add taxes and custom fees it puts the price out of reach. I chose this antenna over the MFJ 1786 as it has 40m  but not 10m. Seeing the solar cycle is on it's way down 10m is not going to be a go to band for me. Having 40m seemed the way to go and thus the MFJ 1788 was chosen. To go along with the antenna Comet has a great way to bring your coax indoors without leaving a door open to the cold. The CTC-50M is a ribbon type coax cable that is supposed to allow you to run it threw a door or window.....now having said that I have read online that some have damaged the cable by slamming a

MFJ 1718

window or sliding glass door on it. I don't plan on putting it to the test in that fashion any time soon. Also I ordered the MFJ 1918 tri pod stand for the antenna. I'm not going to play around with cheap tri pods or ones that are just meant for cameras, don't want to come home to the antenna on it's side and possibly damaged. From what I have read about the MFJ 1918 online it seems to do a great job in supporting the antenna. The last thing I have to pick up from the local hardware store is a BBQ cover for the antenna to make it look like.........yes you guessed it....a BBQ! At this point in time it looks like the ham radio bug is going to have to be satisfied with the KX3 and portable operations. It's a bit cold out these days for op's from the car (-30 with wind chill today) so for the time being I will be putting the Alexloop on the balcony and see how the fishing is.