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.

Feeds and Other Parts....Continued.

Work on the feed continues. Yesterday I had a few minutes to cut the new septum. I had forgotten how soft and workable the aluminum is. The old Delta band saw must have had a fresh blade on it and made short work of the job. I cut everything just a little bit big and will bring it to tolerance with a file or hand held air driven belt sander. This way there are no overshoots.

And the workshops not to bad either! Candlelight Farms
Airport in Western Connecticut.

 File and sandpaper bring aluminum to proper dimensions. Not an easy task without a proper vise.

 Slow going with the tap. Just a few turns then back out to clean threads on tap. Such a small tap is easy to break when doing this by hand. Better to go slow then break off the tap in the work and have to dig it out or re drill both septum and square tube.

 Dry fit.

 Good illustration of how things go together so far.

Feeds and Other Parts

So I have started to collect all the little pieces required for my 3.8 Meter dish project. First on the list due only to its availability and wanting to work inside when its only 10 degrees F here in CT is the Septum Feed.

I have built this feed in the past from KL6M's excellent plans (http://kl6m.com/23cm/23CM-SEPTUM-FEED.pdf) but sold it off with all the other gear I had accumulated before my recent move. Recently along with my old dish I was able to get my hands another septum feed however I quickly realized it was going to need quite a bit of work to bring it up to standard..... Rather then buy all new parts for 75$ from Online Metals I figures I would salvage what I could.

First off I noticed that the measurements didn't work out to the KL6M plans..

The tuning adjustments were in the wrong spot and the septum dimensions were way off. I corrected this by rotating the back-plate 90 degrees and re drilling the tuning adjuster holes and septum screw holes.The old holes were then filled with epoxy and a new coat of paint applied.




















I also realized that I needed to replace all the tuning hardware as well as the feed connectors and probes with new construction.... I was able to salvage one SMA connector that I found to be an Amphenol unit.... Saved me 8$!

The new hardware was made from 1/4 inch brass round stock, brass 1/4 x 20 hardware and 20 mm round discs as the plans call for. I was able to use the Rockwell lathe and bandsaw at work to machine the parts. 

 New Parts...

 Dry Fit...

 Old kitchen tile used to prevent damage to the bench. I used a little flux, solder and a propane torch to heat the parts.

 All soldered up and pretty close to centered.

Cleaned up with sandpaper wrapped around a dowel.

 My new septum material arrived from online metals. The markout is pretty simple if you follow KL6M's instructions closely. I made the determination that the original septum that came with this feed was of unknown design and to thin. The width of the septum, according to the plans, has little effect on performance and a HUGE effect on how easily it is to drill. 1/4 inch aluminum plate makes it very easy.

This is a picture of the waveguide that was salvaged from the old feed. I filled any mounting holes with epoxy, cleaned up any corrosion and threw a coat of primer on the outside for protection.

To step back a bit.

I had previously been operating a 432MHz EME station from a rental cottage on Candlewood Lake in Connecticut. While the view was impressive the cottage was....well.... a cottage and a more permanent residence was in order.

With the purchase of the new place I reluctantly disassembled my station and sold off all the equipment to cover moving costs and reduce my workload. 

The benefit of all that is that I can now begin a rebuilding process with the benefit of hindsight
and correct many of the problems and inconveniences that plagued my old setup.

This blog will serve as a record of that process. I hope you enjoy it!!


Just a few photos:

My old 4 x 16 Element K1FO Yagi array...

 Finally got around to applying for the Worked All Continents award for my activities on 432 MHz EME. Africa was a holdout for a long time!














Homebrew Power Divider constructed from plans in the ARRL Handbook...

 A review of operating procedures... Lets get it right this time...

Some old photo's of my Dad, K3IB's (ex K2IBP) EME station in Belle Mead, NJ circa 1980.. 4 x Cushcraft Boomers for 2 Meters and a W6PO style amplifier.

 

4 x 432 MHz Yagi's of unknown manufacture. These served as the central point of the array to which the 2 Meter boom section attached. 

 Here are some drawings of the design. 

 

 

These are a few pictures of a unique QSL card my Dad received for working Owen Garriot (W5LFL) on the Columbia orbiter. First launched in April of 1981 this vehicle was later lost with her crew of seven February 1, 2003