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Use Phone to Speed Site Visits

You probably have a logging tool in your pocket right now

ARCHTech Regional Engineer Ed Dulaney handles stations in Texas and Oklahoma. The past few weeks he has been experimenting with a new way to log transmitter readings.

Sometimes when Ed visits a site he doesn’t have a working pen or has used up the last log sheet and forgot to bring more copies. He started thinking about a different way to do the engineering logs.

Most engineers now carry a cell phone with camera. Why not put it to use?

Now, when Ed goes to a site he simply snaps a picture of each meter. Fig. 1 shows the frequency counter. In Fig. 2, a transmitter power meter value is displayed.

Left: Fig. 1: A cell phone camera can be used to ‘log’ meters. Right: Fig. 2: A photo of the transmitter power meter.
When Ed gets to his computer, he downloads the pictures into their appropriate station folders. He keeps a folder for each station on his computer, as seen in Fig. 3, and the photos are placed into the appropriate place as you see in Fig. 4.

An added benefit is that the camera records the time/date stamp with each photo.

Left: Fig. 3: Photos are stored in files for each station … Right: Fig. 4: … and each folder holds the pictures of the visit’s inspection.
It’s a novel approach to a mundane task. I imagine this could be relegated to a junior engineer, with the chief reviewing the photos.

Got a good idea of your own to share? Remember, that’s what Workbench is all about. E-mail me at [email protected].

* * *

Bob Meister needed to run an AM transmitter on a dummy load for a while, in order to set up a station’s IBOC parameters. The 1 kW transmitter has a female N connector output, but the dummy load was terminated in a 3-1/8-inch EIA bullet.

There were several solutions: First, he could buy the appropriate 3-1/8 EIA-to-N adapter for about $400. This was too expensive for something needed only a couple times a year.

Bob could connect a coaxial pigtail to the transmitter and use the clip leads from an operating impedance bridge to connect the coax to the EIA connector. However it’s easy to forget to bring the OIB to the site.

The third choice was to make something cheaper that will work as well.

Bob figured that if the open wire connection made with the OIB was an acceptable load for the transmitter, a piece of coax attached directly to the EIA connector also could get the job done.

To construct the cable, Bob cut a piece of RG-214 coax about five feet long (but any length should do) and crimped a male N connector to one end. This end would fasten to the transmitter output.

He prepared the other end by stripping 2-1/2 inches of outer insulation from the cable, then cut off the braid so about 2 inches of center conductor and insulation was exposed. Bob saved the braid, folded it flat, tinned it and wrapped it around the existing braid. He then soldered it to make a ground lead.

To that braid, Bob crimped and soldered a ring lug, then cut it open to fit over the 3/8-inch stud on the EIA connector. Several layers of electrical tape were used to cover the braid connection. He then removed 3/4 inch of center insulation and flattened the inner conductors of the RG-214.

Bob then cut a 2-inch piece of copper pipe that previously had been used as the center conductor in a 3-1/8 EIA environment. This pipe measures 1.225 inches inside diameter and 1.325 inches outside diameter. He cleaned the outside of the pipe first with emery paper then some Noxon brand metal cleaner.

Bob’s Weller 325W soldering gun had no trouble heating the end of the piece of pipe. Bob flooded about a 1/2-inch area on the outside surface at one end with solder, then stuck the end of the RG-214 coax into the puddle, added more solder and let it cool off. The excess flux scraped off easily.

Bob used a 1-inch PVC smooth pipe cap, which fit snugly over the copper pipe. He cut a notch in one side about 1/2-inch wide so it could be positioned around the center insulation of the coax, as seen in Fig. 5. Some clear RTV sealant then was applied liberally around the pipe cap and over the connection to offer some margin of safety. A tie wrap was used to secure the coax to the copper pipe.

Installation was straightforward. The pipe fit snugly over the center conductor of the EIA flange connector. The six studs coming out of the EIA connector aren’t threaded all the way down to the flange, and this was something Bob hadn’t planned on. A bunch of flat washers were used to build up the thickness so the nut would tighten down on the solder lug. See the photo of the attached adapter in Fig. 6.

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Fig. 5: Bob Meister’s DIY connector adapter. Note the notch for the center conductor.

Fig. 6: The connector adapter is installed on the dummy load flange. The best part was the total cost: about $10, most of which was the RG-214 coax and the crimp-on N connector.

John Bisset marked his 40th year in radio in broadcasting recently. He works for Tieline Technology and is a past recipient of the SBE’s Educator of the Year Award. Reach him at [email protected] or (603) 472-5282. Faxed submissions can be sent to (603) 472-4944. Submissions for this column are encouraged and qualify for SBE recertification credit.