KH6CB'S 4 ELEMENT HYBRID MOXON
Editor's Note: One of the strongest signals from the Hawaiian Islands is Sonny, KH6CB. He has been running Moxons on 17 and 20 meters for quite some time, so I was thrilled to hear from him over the air one night describing his latest hybrid moxon. It boasts the ability to tune through a wide range of ham bands. I have personally worked him on this antenna on both 17 and 20 meters with 10+db over S9 signals. Booming is the best way to describe how well this antenna of his works. Here's his story and design notes:
Sonny, KH6CB writes: I have/had a HYGAIN 4 element 17 meter monoband yagi (26 ft boom) and converted this to a 20 meter moxon by attaching wires between the driven element and the reflector (keeping the spacing between the wires per moxon calculator).
The results were (to me) outstanding. I compared it to my other 20 meter moxon further away (about 50 ft) at about the same height (25 ft). Basically the 20 meter moxon on the yagi configuration was (at times) at least 3 S units higher.
I came to realize the two yagi directors must play a tremendous part in this. I was overjoyed but not quite satisfied with another monobander so I proceeded to attach a 450 ohm ladder ling to the same feed point as the coax connection. By using different lengths of ladder line with my antenna analyzer I found more available bands. However, it did cause a problem on my 20 meter band. I used a RS relay at the feed point to switch the ladder line in or out. I can now get from 10 to 80 meters using my MFJ-962D tuner.
Of course I am still experimenting with the ladder line STUB but I am REALLY REALLY happy with the performance so far.Total length of each element:
#1 DIRECTOR: 302"
#2 DIRECTOR: 286"
REF to DE = 123"
DE to #1 DIR= 89"
#1 DIR to #2 DIR= 100"
ALSO, wire between REF and DE is radio shack 18G hookup wire. Waxed line (like dental floss) used to keep spacing.
Above is a picture of the coax and ladder line feed point. Note; RS relay is taped under boom. You can only see the black electrical tape. Another note; ladder line length is approximately 75 ft. It is terminated next to my rig (Kenwood ts-850). Close by so I can try different things ie; coils, caps, etc.
If you need more info, email Sonny at KH6CB @ hawaii.rr.com (email not linked to avoid spammers)
ALOHA SONNY KH6CB