Moonraker Question

[9C1Driver]

I bought a working Moonraker and rotor here locally. It does need some new hardware, bolts are rusty, the wire line around the reflector end is rusted, and one of the gamma's came loose from it's mount.

My question is can I just assemble the verticle section and leave the flat side off until I get some parts for it? If so, can I also run a mast out the top and put my IMAX 2000 above it? Thanks.

 

[MisterFatty]

I bought a working Moonraker and rotor here locally. It does need some new hardware, bolts are rusty, the wire line around the reflector end is rusted, and one of the gamma's came loose from it's mount.

My question is can I just assemble the verticle section and leave the flat side off until I get some parts for it? If so, can I also run a mast out the top and put my IMAX 2000 above it? Thanks.

The Moonraker 4 is a hybrid antenna, taking from both the Yagi, and the Quad Design. You could assemble either vertical, or horizontal elements of the Yagi portion not assembling one polarity would have little impact on the antennas performance. However the wire looped (quad) element would need to be fully assembled.

As for mounting the Imax above it, is shouldn't effect performance any noticeable amount. Personally I wouldn't for a few reasons, but its done quite regularly.

Not big on antenna theory, though I've read a bit, and experimented with my share of them, so perhaps someone with more experience will comment.

I think I would just get the hardware and put the entire antenna together as intended, it would be worth the effort.....

One thing worth noting is to take special care when assembling the hub mounts on the Avanti/AS antennas, I've had a few break on me over the years.

Good Luck, its a nice Old School antenna.....

 

[tmac68]

I would think that going above the Moonraker would put greater stress on the rotor and I would avoid doing it if at all possible.

 

[Marconi]

I built a four element flat side once using a Moonraker. I did not use the quad reflector and made one from other material as a typical yagi element 5% longer. I could never get the antenna to tune until I added the vertical side elements back to the antenna. I didn't believe that would be the case, but it happened to me and I never figured out why. I sold the antenna and it was built as a regular Moonraker 4 and works fine to this day.

Don't missunderstand me when I say it would not tune. The antenna worked, it would Tx/Rx but it just would not tune to a nice low SWR with some reasonable bandwidth.

So, the antenna did work, just not without both polarities installed. I would not let this stop you from trying your idea however, but if you do I would surely like to know how it worked out for you.

If you try it, one tip to save the hubs from breaking is to get some 5/8" wood dowel and cut to fit in the empty holes. You also need to water proof them well to keep them from swelling and breaking the tightened down hubs

 

[9C1Driver]

10-4 guys, thanks for the info.

 

[HiDef]

Late to the party. You should be able to use only the vertical elements with the clod reflector. The part about mounting an Imax isn't good. The vertical mast will ruin your pattern. 1/2 of a vertical mast is bad enough into a vertical yagi. Your situation requires the mast to extend completly through.

You really don't need a seperate vertical anyway. The only azimuths where signals will get knocked way down will be 90 degrees away from the major lobe.

 

[MisterFatty]

Late to the party. You should be able to use only the vertical elements with the clod reflector. The part about mounting an Imax isn't good. The vertical mast will ruin your pattern. 1/2 of a vertical mast is bad enough into a vertical yagi. Your situation requires the mast to extend completly through.

You really don't need a seperate vertical anyway. The only azimuths where signals will get knocked way down will be 90 degrees away from the major lobe.

His install is minus the Vertical portion of the antenna, the Mast and Antenna will have little effect on the remaining antenna.

 

[Marconi]

Late to the party. You should be able to use only the vertical elements with the clod reflector. The part about mounting an Imax isn't good. The vertical mast will ruin your pattern. 1/2 of a vertical mast is bad enough into a vertical yagi. Your situation requires the mast to extend completly through.

You really don't need a seperate vertical anyway. The only azimuths where signals will get knocked way down will be 90 degrees away from the major lobe.

His install is minus the Vertical portion of the antenna, the Mast and Antenna will have little effect on the remaining antenna.

I think I have to agree with MisterFatty on this one. The only problem with going above a vertical in this case and with another antenna like an Imax is allowing enough separation between the voltage node of the lower antenna. I personaly don't like the idea for a lot of reasons, but it is often done successfully if the required space is provided. As far as the mast running up thru the vertical beam is concerned, it is just a matter of tuning the extra element into the match. There may be a bit less performance as a result, but I think it is possible.

Like I suggested though, I think the Moonraker does not work so well without the full array of elements. It may be all about the hubs and the way they provide the important symmetry and when parts are missing that just screws up everything. I did not imagine that would be the case when I started my project modifying the Moonraker, but I got stumped trying to make a single polarity MR on the flat side and I did not get to ever really do what I was planning, to make a "No-Reflector" flat side Moonraker antenna. I did make it, and it worked to produce a strong rejection off of the back none-the-less, but again the antenna would not tune, so I never really tested the thing or the idea any further. Maybe one day though with a new M104 I have.

 

[HiDef]

His install is minus the Vertical portion of the antenna, the Mast and Antenna will have little effect on the remaining antenna.

I went back and read the original post before I posted. I just read it again. It still looks like he wants to install the vertical elements vertically on the boom.
Of course it would work fine with no interaction if he was using a horizontal beam.