Antenna Maintenence

Maintenance of the KPH/KSM antennas, once looked after by a fleet of fearless riggers, is now the responsibility of MRHS volunteers.  While there are many fewer antennas than there were during the glory days of the combined point-to-point and marine services there are many fewer of us as well - and we're not quire as fearless.  Repair and restoration of the antennas themselves is beyond the limits of our ability, requiring work at levels from 50ft. to 70ft. and more.  But we can reach the feed lines, which require frequent attention as well. 

These photos show feed line maintenance at the Bolinas transmitter site and the restoration of a run of 4-wire feed line at the Pt. Reyes receive site.  We had to teach ourselves how to work with the 4-wire lines but we think we now have the only working example of this technology, in North America at least.

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These are the men of the rigging crew in the glory days of KPH and the point to point operation.  They're shown at one of the original 300ft Marconi masts.  There were nine of these that supported the antenna for the rotary gap spark transmitter and later the Alexanderson multiple tuned antenna.  Jimmy Bourne, who eventually became Chief Rigger, is in the bottom row at left.  See the Incredible Radio Tales section for a story about Jimmy.

Service Car 50 ventures into the Bolinas antenna field for maintenence.

Tom Horsfall prepares to tension feeders in the Bolinas antenna field.

Tom Horsfall atop the ladder tensioning antenna feeders in the Bolinas antenna field.  Service Car 50 in the foreground.

Tom finishes the job.

A line of poles support the open wire feeders to antennas at Bolinas.

At the receive site in Pt. Reyes there were once three termination frames, one each for the A, B and C antenna fields.  Only one remains, at the rear of the building.  The designation for many of the original point to point antennas can still be seen on the frame.  A 4-wire feed line was used for each antenna.

Each 4-wire line transitioned into a balanced line that was then routed into the station.

These are only a few of the antenna leads for only one of the termination frames, giving an idea of how many antennas there originally were for the point to point service.

The tension on the 4-wire lines was maintained by a system of pulleys and weights.  Each wire in each feed line thus had to be free to slide through each insulator from the frame all the way out to the antenna.

H frames for the B trunk line march off into the distance.

The transition from 4-wire to balanced line may be seen here.  

Bill Ruck marches off down the line of the H frames toward the apex pole of the V beam, surveying the 4-wire line as he goes.

Bill works on the process of tensioning the restored 4-wire line at the termination frame.

Wire clamps hold tension on the 4-wire as the final termination at the termination frame is assembeled.

Mike Johnson begins the process of hoisting a counterweight out of the ground and securing it to the pulley system that will hold tension on the 4-wire line.

For the first time in decades a counterweight of the 4-wire system is suspended in air, holding tension on the line out to the V beam.  Note the mark on the weight showing how far it had sunk into the ground.

This is the termination pole for two V beams.  The big, terminated V beam extends to the left and is in service.  It is a sloping V beam that's terminated at two posts way out in the antenna field.  It is so large that when we tensioned it the weight of the wire dragged a Hummer along the ground.  The V beam extending to the right of the pole is terminated at two other high poles.  This is the one we plan to put in service.

Mike Johnson contemplates his ascent of the V beam pole.  For some reason he is smiling.

Mike checks his gear before beginning the climb.

Up he goes...

Go, Mike, go!  We call him "Young Johnson" since Mike's the youngest member of our group by far.  It's great to have him as his enthusiasm is infections and he's always ready for assignments like this that daunt the rest of us old guys.

Mike reaches the TMC box that contains a balun transformer to couple the open wire feed for the large north V beam to the Heliax cable leading into the station.  The smaller south V beam is fed with balanced ribbon cable that will connect directly to the 4-wire.