Engineer Richard Cabrera has enjoyed and derived many good tips from Workbench postings. He seldom writes in but felt compelled to do so when he read the Sept. 8 tip about driving a ground rod with a drill.
From a safety perspective, he reminds us, please maintain control and let the tool do the work.
As a young apprentice electrician in the 1980s, Richard met a journeyman who had been encouraged to drive a ground rod with a hammer drill. As he was applying his full weight on the drill, it slipped off and he caught the rod right in the mouth. He had to have extensive maxillofacial surgery. Safety first with any power tools.
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Steve Heaton is the director of engineering for Community First Broadcasting of Iowa. He writes about driving ground rods without even breaking a sweat.
He saw a trick performed by a local electrician several years ago. All you need is a bucket of water.
The electrician poked the rod a few inches into the ground, removed it, poured some water into the hole and reinserted the rod. With an up-and-down motion — reminiscent of someone using an old-fashioned butter churn — he was able to work the rod deep into the ground in no time at all, and with one hand.
Occasionally he would pour a little more water alongside the rod to “lubricate” its movement through the mud.
Steve has used this method several times. The technique works great in rich Midwest soil.
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Greg Muir is principal engineer for Wolfram Engineering in Montana. He too has been following the continuing column snippets regarding ground rod installation.
Not to beat a dead horse (or a stubborn ground rod), Greg offers additional observations.
First, be aware that natural gas suppliers now use the popular plastic piping for plumbing gas into buildings. With that in mind, steer clear of any underground piping or electric lines. Always contact Miss Utility before digging.
Next, if you do a Google search for “ground rod driver,” you will find a plethora of hits for a neat little fitting that adapts your hammer drill to ground rods of various sizes. It’s a simple approach, much like Scott Christensen’s comment in the Sept. 8 issue of Radio World.
Yes, these bits cost; but so do several boxes of Band-Aids after you’ve pinched your fingers with a hammer or “widow-making” post-hole driver. Besides, a hammer drill will help you through the rocks, compared to an ordinary drill.
To read more “seasoned” experiences, head to forums.radioreference.com. Search for ground-rod-install-horror.
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Consulting engineer Lew Collins was interested to read of the demise of the 4CX300A vacuum tube.
Consequently, he got out his collection of Eimac data sheets to see what might be unique about that tube besides its “breechblock” base.
It appears to Lew that the only significant difference between the electrical parameters of the 4CX300A and the 4CX250 family is the maximum plate voltage. Lew suggests that it is probably because of a longer leakage path across the ceramic insulator between the plate and screen grid in the 4CX300A than found in other similar ceramic tetrads.
Since Lew is not familiar with the particular Harris/Gates transmitter that uses the 4CX300A as a driver tube, he can only speculate. But because the transmitter design used a common supply for both the driver and PA tube, providing a separate low-voltage supply would be the first step in evaluating a substitute tube.
It might be possible for someone who is committed to keeping one of those transmitters in service to add a separate driver plate supply, at a lower voltage. Then change the tube socket to use a tube from the 4CX250 family. Those sockets seem still to be available from several sources.
Any takers? Let us know your results. I’m at [email protected].
Fig. 1: A metal cage around an outdoor air conditioner discourages theft. * * *
Last issue, we talked about theft problems, including theft of outside air conditioning units.
Fig. 1 shows a good solution that will discourage this cut-and-grab theft.
Sure, the padlock can be cut; but enclosing your units in this kind of steel cage makes the thief work harder. Odds are that he’ll pass up your unit for an easier take.
Thanks to Engineer Jonas Emechebe of Radio Nigeria for this tip.
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Wes Boyd at Cumulus in Youngstown, Ohio, sent in a YouTube link prepared by the Space and Naval Warfare (SPAWAR) Systems Center Pacific in San Diego.
Antenna engineer Daniel Tam has developed a technology that uses the magnetic induction properties of seawater to couple RF signals into a very narrow stream of water. At YouTube, enter “Sea Water Antenna” in the search box to view a video of the antenna in operation. The column of seawater becomes the antenna element.
Fig. 2: A researcher at the Space and Naval Warfare Systems Center Pacific in San Diego has developed a technology that uses magnetic induction properties of seawater to couple RF signals into a very narrow stream of water.
Tests have been conducted on HF, VHF and UHF frequencies. Although the idea is to create an emergency antenna for the commercial and recreational boating industry, land use is also possible by enclosing the salt-water stream in a thin plastic tube.
John Bisset marked his 40th year in radio in broadcasting recently. He now works with Tieline Technology. He is a past recipient of the SBE’s Educator of the Year Award. Reach him at[email protected]. He can be reached at (603) 472-5282. Faxed submissions can be sent to (603) 472-4944.
Submissions for this column are encouraged and qualify for SBE recertification credit.