Not as easy as it sounds - or a piece of cake?
To enable switching of a large number of antennas in a two radio setup, and get a smooth solution, calls for a lot of consideration. We E-mailed a rough sketch with our plans to WX0B, Jay Terleski of Array Solution, www.arraysolutions.com.
He answered very promtly with a suggestion using 2 RatPaks and 4 SixPaks. Each RatPak can switch 6 antenna feeders to one feeder and each SixPak can also switch 6 antenna feeders but to 2 feeders. One for each radio.
Just hook up 4 SixPaks that handle all together 24 antennas. Connect the 4 + 4 feeders leaving the SixPaks to one RatPak each. In this way two feeders from the shack can be switched to any of the 24 antennas. Furthermore this can be extended with two more SixPaks and will then handle a total of 36 antennas should it ever be called for.
All feeders between the shack and the masts as well as the 4-SQ on 80 m are Cellflex 7/8" to lower the losses as much as possible. All jumpers from the 7/8" to the Pack Rats, Six Packs, Stack Masters and Shack are made from Ecoflex 15 1/2" cable. All cables are connected by N-connectors.
RG213 is used between the Stack Masters and the antennas as well as feeders for the 1.8 MHz antennas and the VHF & UHF yagis.
The maximum loss is less than 2 dB to any given HF-antenna. In all about 1700m (5577 ft) of coaxial cable is used - 800m 7/8", 300m 1/2" and 600m RG 213.
The picture above shows to the right the RatPak for Radio 1. Above are the SixPaks for Mast 4 14 - 28 and Mast 4 FB 505.
In the middle of the picture are the StackMasters for 7 - 28 MHz. To the left are the PakRat for Radio 2 as well as the SixPaks for Mast 1 (1.8 - 28 MHz) and WARC LS. The Top-Ten band decoders are shown at top left and top right.
During the contests on 28 MHz in the winter of 2000/2001 an extra 1/4 wave vertical were fitted to the WARC LS SixPak. It was very efficient to only switch between 3 positions on the RatPak of Radio 1 to select the stacked array, the single 4-el yagi pointing to Europe or a vertical.
The COMTEK, www.comteksystems.com, box is used for switching the directions of the 4-SQ on 3.5 MHz.
It takes some time to get used to the switching especially with 2 radios involved - It is very easy to be confused and at the beginning we mix the knobs and had to think for a while of what we were doing.
Occationally a relay has malfunctioned and needed some re-soldering or tampering to function properly. For framelegs (>35 mm) on the mast an adapter plate is needed to fit the Stack Master or Six Pak.
Problem was also encountered with the BIP/BOP switching on the Stack Master. The stacking never worked as expected with the BIP/BOP connected. Once the "out of Phase" box was removed the stacking worked as expected. The decision taken was to abandon BIP/BOP for the time being and check the problem.
The switching of the rigs can be viewed on the 2 radio page.
All cables are led into LS (lillstugan). LS is a small hut about 50 m from the shack where the switching of the cables is made. The feeders are run from this hut to each mast. The shield of the feeders are grounded at each end and a copper wire is run parallel with the feeders about 0.5 m below the surface.
The two RatPaks and two SixPacks (1.8 - 28 MHz and WARC LS) are located in the hut . The rest of the SixPaks are located on Mast 4. The Stack Masters are located on various heights on each of the rotating masts. To the left are the white control cables for the all the switches. A 200 wire cable is leading to the shack.
The control cables to the masts are made up of 20 wires. In all about 1000 m of control cable is used. All cables are connected together on the aluminium sheet on the wall by using 10 standard low voltage terminal block for 20 connections each. Surge protectors are also fitted to these.
The 7/8" feeders are connected to the 1/2" jumpers.