Your browser is out-of-date!

Update your browser to view this website correctly. Update my browser now


How to Find Old Xmitter Parts

We’ve all worked for owners who thought transmitters last forever, but the truth is that as a transmitter ages, the availability of parts becomes a real problem.

(click thumbnail)Fig. 1: Make sure the flapper in the generator stack moves freely. We’ve all worked for owners who thought transmitters last forever, but the truth is that as a transmitter ages, the availability of parts becomes a real problem.

Because many failures involve the power supply, a reliable source of such components is good insurance, especially as a manufacturer’s supplies dwindle.

Dave Biondi, who hosts the [email protected] listserv, offers up the site as a good source of high-power rectifiers. The phone number is (800) 556-3618.

Another source, offered by Tony Mulligan of Mulligan Technical Services in Montana, is Surplus Sales of Nebraska at (402) 346-4750 or on the Web at

Surplus Sales has the IR stacks used in some Continental transmitters as well as the Unitrode “puck”-style diodes found in the Harris MW-10. In addition, it stocks mica and vacuum capacitors.

Finally, Bill Bowin of Columbus, Ohio, suggests contacting Larry Cagle of Electronics Manufacturing Inc. at (800) 556-3618 or via e-mail to [email protected]. This company manufactures the OEM stacks for some of the Continental, Harris, BE and CCA rigs.

. . .

Harlan Bieley, M.D. – medical doctor, not music director – commented on our suggestion for the need for periodic generator engine oil analysis, instead of simply changing the oil.

Dr. Bieley writes to tell Workbench that Jiffy Lube has an engine oil analysis program, with on-site analysis machines from Global Technovations. They call it a “blood test for your car.”

Oil analysis for any engine can spot problems before they become catastrophic.

. . .

While we’re on the topic of generators, cold weather (snow and ice specifically) may require dependence on generators soon. A visual inspection, at the very least, is warranted.

Fig. 1 shows the stack of a generator. Check the little flapper to make sure it moves freely. If it is missing, replace it before the ice and snow arrive.

Inside, check fluid levels, belts and the battery terminals. Look for leaking fluids and correct the problem.

Your generator will be your backup this winter. It must be reliable when called to serve. A thorough maintenance plan by a reputable generator service company is money well spent.

. . .

Have you had fun with some of our “wiring nightmare” pictures?

It’s always rewarding to hear from readers of this column, especially when they are committed to educating their management about engineering, as our recent pictures did.

Stephen Blodgett, director of technical operations for KNX(AM) and KCBS(AM-FM) in Los Angeles, writes, “As a group, engineers have failed to effectively communicate the need and nature of our work to upper management. Without education, the electronic world that we live with remains evasive and troublesome to management and ownership.”

The result, he says, is that engineering essentials often are undervalued and misunderstood.

“I have found that most corporate management appreciates the engineer who can effectively communicate the need.”

Photos certainly can be worth a thousand words, and can be useful in getting your point across.

Include faulty parts in the mix. Show your manager the parts damaged by lightning or a blown power supply capacitor. It’s like getting the parts back when the mechanic repairs your car. You know the job was done.

. . .

(click thumbnail)Fig. 2: The Doctor Series Scratch Repair Device resurfaces your CDs.Gary Leonard of KWWR(FM) and KXEO(AM), Mexico, Mo., was reading a B-Net thread about cleaning vinyl records and just for fun punched in The company still exists.

George Kelly of Kelly Engineering Services adds that Discwasher sells an excellent touchless CD washer that uses a high-speed motor. It spins CDs in a surfectant bath to remove oils, dust and dirt without touching the surface of the CD. The product costs about $60.

What do you do when the CD is scratched? Wendell Hall of WJFK(AM-FM) in Washington showed me a slick device manufactured by Digital Innovations, shown in Fig. 2.

The Doctor Series Scratch Repair Device is a manually operated product that radially resurfaces CDs. This action repairs the primary causes of skipping and distortion, and will repair abrasions, light to medium scratches and surface imperfections.

With its “reversibility”feature, it can repair deeper, more stubborn scratches.

The company offers tips on caring for CDs that can be found at Select “About CDs.”

. . .

(click thumbnail)Fig. 3: Seal your buildings for winter. Rodents will look for escape from the cold.
Have you sealed your buildings for the winter? Fig. 3 shows the inside of a phasor with three openings at the lower left, ideal doorways for mice (first arrow).

The RF lines that lead to the outside are sealed with the white Teflon-brand bushings seen at the base (second arrow).

Check for little things like this, and at the least, plug the holes inside the building with steel-wool plugs.

Mice can chew through wires, and not until you’ve had to replace chewed control wiring will you appreciate the importance of these seemingly “minor” maintenance checks.

Submissions for this column are encouraged, and qualify for SBE recertification credit. Fax your submission to (703) 323-8044, or send e-mail to [email protected]