"A Cost Effective Way to Listen to Television"
A review of the Radio Shack 12-604 (Part 1)
By: Frederick R. Vobbe, Chief Engineer WLIO Television
February 10, 1998

I can't tell you how many times I have wanted to just listen to the audio of our station while working in my office. Likewise, when the news department requires a way to hear "off air" audio during a live-shot, it can be a hassle to drag a portable TV out, and connect up an earpiece. A typical television for this application might be a small black and white television that is powered by 110 volts AC. These list for around $100.00 to $150.00. Battery powered portables are more, and the battery life can disappointing.

So what if you don't have to see a picture? Enter the Radio Shack 12-604 receiver. In the past there have been radios that receive VHF television audio, but this is the first that I have seen which has included UHF television channels!

The radio measures 13.6" wide, around 9" high (sitting on a desk), and is about 4.25" deep. The 12-604 can be powered using an attached 110-volt power cord, or (6) six D-cell batteries. It has an attached handle on the top to carry the radio, and includes a 32" whip antenna that telescopes out of the back. On the back of the radio are terminals for external antenna connections, AM, FM, and TV. The antenna connections are sort of strange as they break up the television spectrum into five bands. The television band is broken into the following bands. TV-1 is channels 2 through 6. TV-2 is channels 7 though 13. UHF-1 is channels 14 to 32 (474 to 587.3 megahertz), UHF-2 is channels 33 to 51 (586.3 to 701.3 megahertz), and UHF-3 is channels 52 to 71 (700.3 to 819 megahertz). The radio also covers AM (530 to 1710 kilohertz), FM (88 to 108 megahertz). Sliding a switch on the front of the radio to the appropriate band performs tuning. You then select the actual frequency by a knob on the right side of the radio. The frequency is read out by a "sliding scale" tuning dial.

Besides the volume control, there are also bass and treble controls on the right front of the radio. The power switch is on the upper left, and top. The radio has a large speaker in the front with a companion tweeter. If you have ever seen a GE (General Electric) SuperRadio III, the 12-604 has a striking familiar look to it! The sound is from the speaker is very impressive, and can be loud enough to fill a small room. There is a jack on the side of the radio for a headset, and I found that I could drive several earpices to a comfortable level without distortion.

Performance is fairly good. I was twenty feet from our transmitter on channel 35, and did not experience any overload, or audio degradation. On the other hand, with the radio in the building, using the whip antenna, I could receive the PBS affiliate thirty miles to the north, which is just eight channels below us.

How could this radio be used? One application might be a portable "off air" monitor in a live van. The radio could be easily set up with a single earpiece while doing a standup in the field. Or, the radio could be left in the van and the audio fed to the newsperson through an extension cable. An enterprising engineer could also design a rack mount for the radio, and I'm sure it would sound very good in any truck as a stand-alone receiver.

The radio could also be used in the newsroom to monitor your newscasts, or your competition. It could also be used to pick up and relay to a wireless IFB. Your engineer could use it in their shop as a quick way to monitor the station.

The cons? There is a switch on the back of the radio that selects battery or AC line operation. I can see where this could be overlooked, which would result in some tense seconds prior to a live shot. If you use this in a remote operation, your operators need to know where this switch is.

If I have not praised this radio enough, here is a plus. A gentleman in Minnesota has a modification for this radio to pick up the FM SCA or the Television SAP channel. The modification is a very cost effective way to monitor your SAP channel, or provide people in the community access to programming on SAP such as Book for the Blind, World Radio Network, or Bilingual broadcasts. In part two of this article I will review the SAP operation in detail, with test results.

The Radio Shack 12-604 sells for $79.00 in most stores. If you are interested in the radio with the SAP modification installed, it is available for $120.00 from Bruce Elving, 241 Anderson Road, Esko, MN 55733.

I have no affiliation with Radio Shack. I just found out about this radio through one of the local talking books, and purchased one to check out the hype. It's well worth the investment for any operation which has a need to monitor their station's "off air" audio. It is also affordable for any member of your viewing audience.

Frederick R. Vobbe

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Fred Vobbe is the Chief Engineer for WLIO Television, and is the editor for the National Radio Club's DX AUDIO SERVICE (books for the blind) which publishes magazines of interest on the subject of listening and watching broadcast radio and television. Mr. Vobbe also authors other papers of interest on managment and programming issues.