I just finished replacing the crank up antenna mast with the fixed Jack antenna mast. Having completed this, I would not recommend this solution to others for the following reasons:
1. Do you really need to replace your old antenna? The Signal Commander is a powered antenna just like the Jack. My reception is about the same as before the replacement. A number of people have found bad coax cable crimps when they did the replacement. The bad connectors may have been the major reason why they had poor reception.
2. The factory used two holes to install the Signal Commander. One for the coax and one for the crank up mechanism. The Jack pedestal will only cover the major hole. The coax cable hole is outside the base of the pedestal and will have to been filled and patched.
The patch in the Dicor patch kit is not quite large enough to go a great patch. They recommend a 2 or more inch cover of the hole from the edge of the patch. If you put the patch under the new mast, the patch will only extend about an inch beyond the coax hole.
3. The Jack mast stands a little higher than the air vent covers. My concern is tree branches hitting this unit. IF you just replace the head on your existing antenna mast, the antenna will be less likely to be broken off.
The material of the Jack antenna is plastic. This unit should shear off fairly easily if you hit a tree branch. The rotation portion of the antenna is plastic, so this should not be a problem. The coax cable will be problem if the mast is sheared. This will cause the head to pushed into the rubber roof material, causing a tear.
My reason for the complete mast replacement was to have the signal indicator right at the directional mechanism. In hind sight, the separate signal meter could have been attached to the bedroom TV port and the old crank up unit could have been retained.
The power amplifier for my Signal Commander worked fine with the Jack antenna. No replacement required.
If you are having problems with your powered antenna on your RV:
1. Check the coax cable connections. You may have to take the old unit off tho get to the connectors on the roof. The old antenna mast can be installed using the existing holes. You will not have to patch or drill new holes, only re-chaulk the old mast,
2. Install the Signal Meter on your bedroom tv port, either directly or through a splitter if you have a bedroom tv. This may help you find stations better and you may not have to replace the antenna head.
3. Replace only the head of the antenna with the Jack head. The installation is quick and easy. This will also provide better clearance for tree branches.
There is the easy way and the hard way. I think I chose the hard way.