[Milsurplus] Naval Aviation Navigation

[Ed Zeranski]

I collected a couple or ARN-52's, a control head, antenna, and big monster
TACAN
test set (which is quite impressive)
........... these TACAN units seem so quaint...

Yet they did the job.  Anyone have experience with these particular units?


	I never worked on the ARN-52 but did spend time with the ARN-91 and 118
series used in F4s as well as ground/shipboard base stations. With the
ground stations we had to run periodic real-time tests with an FAA flyover
to check station accuracy as well as the accuracy of the monitoring
equipment.  DME, range/Distance Measuring Equipment, had a 200 mile range
but I can't remember the accuracy spec. AZ info had to be within 1 degree on
land stations and 3 degrees at sea.

	We did annual antenna tear down and rebuilds too. The antenna element was a
stack of cones surounded by a spinning fiberglass drum with nichrome
parasitic elements in it. At 900 rpm one parasitic modulated the transmitted
pattern at 15cps, 9 secondary parasitics produced 135 cps modulation. Our
rebuild replaced all the bearings, reworked the spin motor, and checked out
the magamps that controled speed etc. Then was the fun part...balancing the
spinning drum. The ant would be run to speed and checked with a strobe light
through a peep hole in the cover. If a # showed up in the strobe we had to
and or remove trip washers like balancing a big tire...very tedious.

	A I'm not sure what the legality of using the range function is since that
interogates the ground station, AZ and ID (in CW, North Island was NZY) are
RX only. Working the base sites and other comm/nav was fun because the sites
were usually a bit remote and that meant you could be pretty independant.
One site had a GRN-9 that used a SAL-39 klystron power amp that had no
control grid so the cathode got whacked with a -12KV pulse. The pulse tube
was a 4-1000. The FAA said the tubes had to be changed every so many hours,
can't recall that number either, and the tubes were not recycled. One old
guy had my schedule down pat, he would be waiting at the site on change day
to harvest the two tubes. We had one site that had a 206KC beacon used by
seaplanes. The antenna was a verticle with large tophat. Not sure how tall
it was but it sure like a long way down when we cleaned insulators etc.

EdZ