Having some SWR trouble with the MFJ 1890 10 meter moxon

[Beetle]

Periodic calibration of test equipment is absolutely necessary, and that doesn't mean "checked against another meter" unless the "other meter" has a current calibration date.

 

[John David Trolinger]

In the spirit of letting you know how it went...

Thanks Alan this was helpful to me as this weekend I took down my MFJ-1890 to clean and adjust, the 10 year checkup as it were. Of course I had to mess with the thing and now the SWR is higher than I want. Work in progress. Completed.

After several ups and downs the 10M Moxon is up about 40ft on a push up mast.

 

[S&W357]

Old thread but informative for me. I soon will be putting a MFJ 10 meter Moxon together. The instruction sheet for assembly is not very clear to my 79 1/2 year old brain.

 

[S&W357]

The assembly instruction sheet is clear to me now. Clear enough to realize two pieces of aluminum tubing are missing from the box. HRO working on fixing that issue.

 

[S&W357]

Five days after sending HRO an email regarding the two missing piece action took place. HRO contacted MFJ. I was copied on all emails.

MFJ emailed me apologizing for the missing parts. Four working days later a box from MFJ was delivered to my house. It contained six of the aluminum tubes that I only needed two more of.

Great service from both Ham Radio Outlet and MFJ

 

[Crawdad]

It contained six of the aluminum tubes that I only needed two more of.

Hey Ralph,
Now you can do a Moxon for 6m.........

 

[S&W357]

Up without a rotor but that is forthcoming.

 

[Dusty1USA]

Old thread but I just put an MFJ 1890 in the air last week. Adjusted the element dimensions for 11 meters.
Adjusting the length of the director on the short sides worked for setting the swr.
I ended up with 1.1 on ch. 1 and 1.3 on ch. 40.
Receive and TX performance is outstanding compared to my Tram 1498 vertical and a home made inverted V dipole I have hanging in some trees in the yard.

However I'm wondering if I am getting as good F/B performance as I should out of it. Any suggestions on how to tune the reflector element for the F/B performance?
I'm assuming it will be the adjustments on the short sides that will make it better or worse like it was for the swr.
I tuned it laying on some sawhorses in the yard and the tune didn't change when I got it up on a 27' mast.

 

[Crawdad]

What is the frequency you are tuning to?

What is the O.D. of your tubing?

 

[John David Trolinger]

Old thread but I just put an MFJ 1890 in the air last week. Adjusted the element dimensions for 11 meters.
Adjusting the length of the director on the short sides worked for setting the swr.
I ended up with 1.1 on ch. 1 and 1.3 on ch. 40.
Receive and TX performance is outstanding compared to my Tram 1498 vertical and a home made inverted V dipole I have hanging in some trees in the yard.

However I'm wondering if I am getting as good F/B performance as I should out of it. Any suggestions on how to tune the reflector element for the F/B performance?
I'm assuming it will be the adjustments on the short sides that will make it better or worse like it was for the swr.
I tuned it laying on some sawhorses in the yard and the tune didn't change when I got it up on a 27' mast.

My 10M Moxon is good at nulling out loud stations and when pointing it at weak stations is helpful but it is only 2 elements right?
This Moxon is my wife's favorite antenna so I spend the time and effort to make it close to perfect. The antenna is on it's own push up mast, I think 33ft up on top of one of those RCA/Radio shack rotators.
The last time that I took the moxon down for refurb and tuning I put it up in the air a couple of times in order to get the SWR right. To keep the RF out of the shack I do have an air choke at the antenna and an iron core choke in the shack.
This diagram is from the original instruction and the stuff in GREEN my changes and measurements.