Dish Systems For Sale

A number of hams have asked me whether I could provide them with mounts and feed sysems like those described on this webpage. I have tried to show all the details needed to make these systems yourself, but many have told me that they don't have the time, tools or talent to do the mechanical work necessary. Contact W8GSM, K0DJV, W2CO or KB5RRR to find out how they like the mounts that I made for them. If you think dish prices are high, you haven't priced HF towers, rotators and beams recently!

Many think that AO-40 is such a lemon that it takes a monster sized dish to work it. Not true. Even the 18" DirecTV hubcap sized dishes will pick it up. But like most fields of human endeavor, bigger is better! EME is going through change as well. A medium sized dish in the 7' to 14' range, and JT44 freeware with soundcard based DSP puts you to the Moon and back now.

Most of the BUDs that I have obtained are 7 1/2' in diameter mesh dishes. Smaller units do not pick up as much signal, but are portable and work great especially when the signal is strong. I have used these dishes to develop the ideas found on this webpage, and I am offering several of them to you. The cost of the dish is a small part of the whole package cost. The expensive part of the system is the sprockets and chain, the bearings, the gearmotor and the precision potentiometers and at least a week or two of assembly time. The heavy part is the steel tubing. If you can use as much of your own TVRO dish and mount as possible, the freight costs go way down, but the system cost is only slightly impacted. Below are some systems that I have built so I could write this webpage from actual experience. Now I want to let them be used and have included a reasonable cost amount for your e-shopping convenience. If you already have a feed system and/or a downconverter, the cost will be lower. If you are interested in a complete dish & mount, arrange a scenic trip to Colorado in your pickup or SUV or Van to pick it up. Most of these systems are quite heavy, so I really don't want to have to ship them.

7 1/2' Aluminum Dish with Portable Post

This dish and mount is built for about 300 degrees of azimuth rotation, making it great for AO-40 and DSP based EME. The aluminum mesh dish is in very good shape, painted grey in color. The mount is shown on its portable base, a steel post with heavy duty 5" swivel and lock wheels on detachable tripod legs freshly painted with powder coat black paint.. The mount can also be slipped over a standard 3 1/2" diameter steel post at least 4' high set in concrete, as a permanent AO-40 dish. The picture at the left shows a circularly polarized 2401 MHz S band downlink patch with an SSB UEK-3000 downconverter to 145 MHz on the dish. I would recommend you go all the way with this dish, and put a Tri band circular patch feed and AIDC 3731 downconverter.

The picture at the right shows the tracker arm used for moving this dish in elevation. It also shows the chain drive system near the top of the mount and the heavy duty 3 RPM DC Gearmotor and V belt used to move the dish and mount in azimuth.

Cost: 7 1/2' dish, mount, motors, precision potentiometers, the portable post, the Satellite Tracker Senior, a 16 VDC @ 4 A power supply, and 100' of cable is $1800.

If you want the 7 1/2' dish system with the optional 2401 MHz patch feed ($75) and an SSB UEK-3000 downconverter ($460) the system price comes to $2300.

If you want the 7 1/2' dish system with a Tri band circular patch ($300) and an AIDC 3731 downconverter (also available from k5gna@aol.com for $120), the system price is $2100.

These systems are available now, ready to attach coax to your satellite rig and work AO-40. Bring an SUV or pickup and take it away.

.W0LMD Feed Systems for your Dish

Several people have asked me to make helix or patch feed systems for their dish.

Peolpe have told me that they lack the time, tools or expertise to successfully complete the project. The helix systems for 2401 MHz are just a couple of feet of bare #10 copper house wire, a 4" shiney aluminum disk, and a type N, male or female, connector.

Patch antennas for 2401 MHz are even easier to make. A 4" shiney aluminum disk, a 2 5/8" soup can lid (or get fancy and obtain some 1/16" brass sheeting from your local ACE hardware or hobby store), and a type N, male or female, connector. I make this circular polarized by capacity loading it out of phase. I concentrate on fully utilizing the dish netting a few extra db from a higher efficiency dish. Making it really circular polarized gains 3 db which is equivalent to doubling the surface area of your dish. A bit of work on the feed and its placement can net you the equivalent of doubling your dish in size.

I made a 2401 MHz patch feed, shown at the left, that had a reflector the same size as the C band Chaparral feed that had been on the TVRO dish. The bolt hole spacing was the same, so it was a simple unbolt and replace operation.

4' or larger centerfed dishes on AO-40 do well with multiband patch feeds.. I cut aluminum circles on my bandsaw to make a great looking dual patch system. It takes a bit of effort get the SWR down on the 435 MHz patch, shown at the right on the dual band (S & U) patch. I use a $700 graphic SWR meter from AEA called a 140-525 Analyst to get an almost perfect match. Some may question whether it is worth the effort to achieve circularity on the transmitting patch. AO-40 operators have found that stations with circularly polarized uplink signals show considerably less QSB, especially during high squint angle times.

I tune a dual band (S & L) circularly polarized patch, shown at the left, by using an ICOM T-81A handie talkie as a 1 watt signal source on 1268 MHz into a Diawa 801S SWR bridge. With considerable twiddling on the two tuning screws when mounted on a TVRO dish I can get an almost perfect match.

A triband (S, L, & U) circularly polarized patch feed for AO-40 is shown in the picture at the right. It uses 6 disks carefully placed in an axial line. As shown in the picture at the right, additional holes must be placed in the lower frequency disks to not only let coaxial connectors to be attached, but also provide clearance for the tuning screws.

Also shown in the picture at the right is a cross shaped adjustable feed support for 4 arms feed support systems commonly used on TVRO dishes. This feed support rigidly holds the large feed system and lets the feed systems with a large 435 MHz feed be easily focused to the same point the old Chapparal feed was located. This avoids cutting the suppot arm lengths to focus the triand patch feed assembly.

Cost

I charge $75 to make & tune a single band feed system, $200 for a dual band system and $300 for a triband feed system. A dual circularity triband patch feed for AO-40 and EME costs $400. The cross shaped feed system holder is $25.All prices are postpaid 2nd day priority US mail in the USA. The cost of the metal is low. It takes a couple of days to make and perfectly tune the triband patch feed. The triband patch feed uses almost $50 worth of type N connectors & adapters. The tools, test equiptment and time is what adds up.

Robert W0LMD          robert@ultimatecharger.com          Conifer, Colorado        (303) 838-6346