Hi friends. I thought some of you might enjoy seeing some really beautifully built antenna equipment by Rohde & Schwarz.
This is a fascinating antenna coupler. There were two variations of this. One for use with a vertical or long wire (FK859).
https://w2hx.com/x/RohdeSchwarz/FK859/Pix/0525181435.jpg
And another variant where the HV top was replaced with a dipole adapter where this whole thing (weighs over 200 lbs) would be mounted aloft. The dipole adapter held four horizontal radiators to make the dipole. That variant is called the
HX002. https://w2hx.com/x/RohdeSchwarz/HX002/aloft.jpg (stock photo!)
I have a bit of a hybrid approach where I have the 859 base and the dipole attachment at the top, which gets the HV wire over to my vertical.
https://w2hx.com/x/RohdeSchwarz/FK859/With%20HX002/1103201618a.jpg
I’ve been using this in my shack for a few years and I really love this coupler. It is spec’d for 1.15KW CCS but in ICAS SSB service I would say 2KW (maybe even 5KW) would not be a problem. What I like about it is that it accepts 50W-300W
for tune power. this makes it really convenient for tuning 100-150W transmitters where you can simply key up at full power and have the unit tune. Past couplers I had forced me to lower output to certain levels (not too low, not too high) which was always
a little involved to get it just right. Although I chose to run about a dozen lines from it into the shack, this R&S coupler can be set in “auto” mode and needs only 28VDC and nothing else.
So this has worked really well for me for a while now. Recently I acquired a 1KW Harris transmitter and while I was learning how to use it, I must have accidentally dumped about 1.5KW into the coupler before it was tuned up and I believe
I have fried the directional coupler. If I don’t get this fixed before the winter weather really sets in, I’ll be QRT all winter. So today was a warm and sunny day and I decided to take it apart to pull out the directional coupler and see what was what. This
thing is quite heavy and thoroughly installed outside so I thought I would take it apart, bring back the directional coupler to the workbench.
Most of the control circuits are mounted on removable modules accessible through this front door which tilts down.
https://w2hx.com/x/RohdeSchwarz/FK859/Pix/0525181508.jpg
But as my luck would have it, there is one module that requires the whole top to be taken off to access it. Big job. And here are some pictures. The build quality is really spectacular.
First step was to remove the dipole adapter to reduce the weight of the shell.
https://w2hx.com/x/RohdeSchwarz/FK859/Pix/Top%20Removed%20for%20Repair/20211113_123707.jpg
And the internals.
https://w2hx.com/x/RohdeSchwarz/FK859/Pix/Top%20Removed%20for%20Repair/20211113_132351.jpg
There are 32 motors around the base, 8 on each side. Each motor actuates a push rod that forms a switch to switch L and C components in and out until it finds match. Everything is silver or gold plated. Tuning is pretty fast on this and
it remembers the Ls and Cs for each frequency so subsequent tuning is very fast 70 ms – 500 ms when a solution is stored in memory.
And finally the directional coupler was accessible.
https://w2hx.com/x/RohdeSchwarz/FK859/Pix/Top%20Removed%20for%20Repair/20211113_132402.jpg
https://w2hx.com/x/RohdeSchwarz/FK859/Pix/Top%20Removed%20for%20Repair/20211113_132540.jpg
https://w2hx.com/x/RohdeSchwarz/FK859/Pix/Top%20Removed%20for%20Repair/20211113_132452.jpg
But just as I was strategizing about its removal. I heard thunder and realized some weather was moving in rapidly that I hadn’t noticed! So a mad scramble ensued to get everything back together to a reasonable degree and pack up the tools
and get in the house!
Well that is my story for Saturday. Hope it was of some interest.
73 Eugene W2HX
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