The Lunar Letter

 I recently dug out all my Dad's old issues of The Lunar Letter for late night reading and thought there might be some interest in the current EME community. I'm trying to figure out a way to post them and will scan as many as I can as time permits. 

This is a work in progress and I have zero interweb skills so please forgive me or offer help!!

The Lunar Letter:

March 1982 https://drive.google.com/file/d/1Knr2rbebrN_0_bBW16KCjbcaVR6BfMGh/view?usp=sharing

June 1982 https://drive.google.com/file/d/1kIFzSkRwZZ4bhIpGVIXNSPKgOTfOSPMm/view?usp=sharing

Smaller is better....for me!

I decided that if I was going to be successful at this project I needed to make it more manageable. The 10.5 ft dish was to much to do alone. Some of the spars had damage to the ends, it was to heavy to handle by myself and hard to work on without proper work stands. In the end I did what would make most cringe.... I cut 1'3" off the spars, shortened the screen and reduced the diameter to 2.5m or 8'4". I know it will reduce performance and eliminate the possibility of adding 432 MHz but I think it is worth it. With high power available and digital modes I should still have plenty of people to work. Certainly more then I would if I never finish the project. It just made sense.

In the end after all was cut and re-assembled I think it made a world of difference in terms of manageability. Its 25# lighter and far easier to work on. Plus it fits the trailer better and will probably make it possible to move by road in the future.

Assembly of the 10.5 footer and a big lesson

Some references. Great article on Polar mounts and the KL6M feed.

The polar mount explained....

http://www.w2drz.ramcoinc.com/polar_mounts.htm

Cheap and easy 1296 feed...

http://kl6m.com/23cm/23CM-SEPTUM-FEED.pdf

Dish feed for 432 MHz...

http://www.ok1dfc.com/EME/technic/432feed/OK1DFC%20432%20MHz%20Loop%20feed.pdf

Dish Assembly

Some calculations were required once I figured out the dish dimensions. 

  Initial assembly on fence post in order to take initial measurements. 

 Details of polar mount

 Temporary wooden mock up on small 40x48" utility trailer I bought off craigs list for 100$. There is no good view of moon from my yard except the middle of front yard and that won't fly with the XYL. 

 These are fittings for the feed mounting support legs. I will cut them in half, turn a few spacers and use rod ends to get some fine adjustability out of the feed mount. 

 Rung-Fu RF-30 from MSC does a great job!!

Pile of Pre Amplifiers

Started making a pile of preamplifier options for 10 GHz, 1296 MHz and 432 MHz.

Down East Microwave - 1296 16dB .70 NF
K4EME - 432 21dB .30 NF
K3IB - 1296 15 dB 1.2 NF
DU3BC - 10 GHz 28 dB .55 NF

Mini Circuits directional coupler for return loss measurements.

Feeds and Other Parts....Continued..

The feed is all drilled and checked so its time to fill in all the old screw holes and make it look nice again. This is more like body work then anything else but I think it will pay off in the end in how it looks. Buying new aluminum would have saved a lot of work and looked better but I really didn't want to waste the material.

Something to note was the corrosion on the inside of the feed. It cleaned up pretty easily but I think it deserves some clear
coat in the future to prevent it from growing again.

 A little sanding cleaned up all the extra epoxy.

 I put a few coats of primer and enamel from a rattle can. I found that spray cans just don't do well with large surfaces so I borrowed a technique I used on my Cessna landing gear. A foam paint roller and rustoleum enamel will leave a nice finish if you take your time. Here is is baked in front of the wood stove for a few hours to speed things up.

 The finished product.

Rough tuned using my Down East Microwave signal source. I will fine tune this later with a directional coupler and power meter.