KØAWU -- 10Ghz "Tower" System

The tower amplifier/preamp has been upgraded now to include one of the DEMI 8 watt amplifiers. I had had such good success with the 2watt system this was a very hard thing to decide on. But a few more DB may make the difference down the log somewhere.

The tower chassis was completely rebuilt to now include the 8watt amplifier. The amplifier requires heatsinking, so the entire assembly is now mounted on a .315" thick aluminum plate weighing almost 2 pounds. In fact the 8watt DEMI base plate is attached to the bed plate through an additional .315" aluminum plate. The amp is followed with a 10Ghz isolator to protect the amp from SWR (like snow on the feed horn).

In the lower part of the photo, the surplus KuBand LNA can be seen, it's used to provide about a 1db NF and 20db gain to overcome the Superflex loss on receive. SMA type relays handle the RF routing for the amp/preamp.

RG8U is used to supply 12V "up top" to reduce voltage drop. A four conductor cable handles PTT, RF monitoring etc.The DC voltage indicating the RF level from the 8w amp is now used to provide monitoring of TX power instead of the coupler and xtal detector used before.

Elevation & Azimuth Control Upgrade -- May 13, 2005

I now have good speed control on the CDR rotator by using a WW2R type speed control . I can run the CDR at it's normal speed or at a reduced speed of about 1 deg in 2 seconds. I built a complete control unit for the CDR with digital readout and added a elevation system built from a Black & Decker cordless screwdriver and a length of 1/4"-20 threaded rod. The elevation can now be varied from -3deg to a positive 15 degs. I then utilized a N1BUG pot based AZ-EL metering system to provide dish position. N1BUG Az/El indicator The homebrew control unit provides digital readout of both azimuth and elevation, it works very well.

10Ghz Tower System Is "Born" -- July 22, 2004

Given the cold weather during the winter and my desire to play with 10Ghz snow scatter, I decided to build a system up for the tower. (Also handy for rainscatter at night or during weather).

My horizon is very limited due to the forest surrounding us. The view north and south are pretty good, up and down the lake. I can look as far as about 30 deg east of south without too much of a problem. Rain Scatter into IL would be nice.

(It was! 7/23/05 10,368.100Mhz 5-2 CW W9ZIH-KØAWU 695Km RainScatter)

The "short tower" was pretty much retired and I had even removed several sections before I decided to put this system up. The 18" DSS modified dish is up at about 55ft.

(The tower on the right has the 6m,2m,222,432,1296 antennas. That tower is a 60ft Universal aluminum rated at 18sq ft 80mph)

My system is a bit unsual in that I wanted to keep the transverter out of the -40deg temps in the heart of the winter.

I use a Yaesu FT290RII 2m rig for the IF into a Khune model MKU 10G transverter (1999 version with seperate LO). The Khune provides about 4mw that is attenuated to drive a surplus Qualcom amplifier to about 400mw. (All of this in the bottom cabinet.) A N6CA type sequencer (center) controls the entire system.

This is in turn feed to the tower equipment via 80ft of Andrew 1/2" Superflex. (Just short of 10db loss at 10Ghz)

At the top of the tower behind the dish, I have the rest of the system in a recycled 1 gal paint thinner can. Cut the top out and this "chassis" slides up into the can and is bolted in place.

This chassis contains a DEMI 2 watt amplifier built up from the kit. The amp is followed with a 10Ghz isolator to protect the amp from SWR (like snow on the feed horn). A 30db directional coupler is used with a xtal detector to provide RF sampling to monitor the amplifier operation. The detector is located among all of the BNC connectors on the left of the photo.

In the lower part of the photo, the surplus KuBand LNA can just be seen, it's used to provide about a 1db NF and 20db gain to overcome the Superflex loss on receive. SMA type relays handle the RF routing for the amp/preamp and the relay top right switches the 12V off the preamp and onto the amp during transmit.

RG8U is used to supply 12V "up top" to avoid voltage drop. A four conductor cable handles PTT, RF sampling etc.

July 31, 2004

As of this date I have worked Gary, WØGHZ in EN34 (155 miles) four times, two times with very slight rain enhancement, once via true rain scatter and once by tropo. I have also worked WØZQ/9 in EN34px Wisconsin via tropo CW 5-1. The biggest single known issue is that the CDR rotator is WAY too quick and my bearing readout is not good enough to "point and shoot". I need to have the other station call me where I can get a good bearing. At this point no elevation control either.

I just couldn't resist. This is the view "sort of" down the feed arm of the 10Ghz dish, looking toward EN34 from 55ft.(Aug 1, 2004 about 5:30pm local)

Similar view down the feed arm of the 10Ghz dish, looking toward EN34 from 55ft.(Aug 22, 2013 about 1:00pm local)