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I've been sorting out some of the confusion regarding Bogen's AM-only tuners and their model numbers. This seems to be the history: There were three styles: 901, 90, 91. 7/17/1952: Drawing AM 901-1 (attached). 1953: Radio Shack catalog AM901, $55.86, no case. SAMS 2-53. 1954: Radio Shack...

Is there a precise definition of public radio?

I have seen some comments that seem to confuse sound quality with reception – thus this post. I think tuner performance can be seen in three main areas: Reception – sensitivity and selectivity. Sound Quality – audible frequency range, stereo separation, fidelity to sound source. Noise...

What sort of interference or distortion causes a sound like a chorus of crickets or tree frogs? I'm getting this sound in the quiet parts when listening to a certain strong station at 55 miles, with intervening mountains. Switching to mono greatly reduces, but does not eliminate, the sound. It's...

Despite very different external appearances (the 310(A) chassis is inverted), the A and the B are virtually identical electrically, except for the RF tube. See http://hhscott.com/fm_tuners.htm. At least, that's what I thought until now. These two chassis photos show that the A has an extra...

I just noticed that, with the Fisher FM-40, one can switch between MPX out and detector out. What's the difference?

Is IC always better?

I have known of a Scott 312C and a 312D that would fail to automatically unmute. The LT-112B also has the same mute circuit. The problem is something to do with hysteresis. The late Ed Von Essen figured out a fix: Shunt R2 (680K) with added 62K resistor. My tech confirmed it. Just wanted to get...

What are the 10, or so, most important technological advances in FM tuner development? A timeline would be helpful.

KCSM broadcasts its regular FM signal at 91.1 from San Mateo, Calif. It also simulcasts at KPJK TV channel 60-6 from San Francisco. For those who have a strong signal from both sources, how does the quality compare?

I have seen two versions of this MPX unit. They appear identical, except for some lettering on the back of the chassis. One indicates “Series A-91” and has a screw labeled “Level”. The other indicates “Series B-111” and labels the screw “Matrix Adj”. I wouldn't think a level adjustment would be...

I got a NOS Archer 15-1636. It arrived broken, but I managed to cobble it together. It's in the 1975 Radio Shack catalog for $11. It has 5 elements on a 70" boom, which is a bit longer than a Stellar 4-element. It has two folded dipoles at widths of 61 and 54 inches, connected by thin, crossed...

What causes static sounds like a geiger counter, even in mono? It might be evident for a few days, then gone for a few days.

Please recommend the good, the bad, and the indifferent.

Brian's review of the Stellar antenna and the addition of a fifth element is here: http://ham-radio.com/k6sti/stellar.htm The mod appears designed to make best use of a 96-inch piece of aluminum angle bar. But what if that constraint were removed? What would be the length of the new director...

Is there such thing as crystal clear FM stereo? I always hear at least some noise switching from mono to stereo. I know multiplex stereo has some inherent problems, but I'm not sure they are always audible.

The 311 has a stand-alone AF tube, whereas the 314 AF shares a tube with the limiter. Does that mean the 311 will sound better? The only other differences I see are the front-panel volume control of the 311 and the better dial design of the earlier 311s. Of course, the 314 has a wider chassis...

I have a question about the 310 series. Scott advertised them as having 3 IF stages and 3 limiter stages. There are 2 limiter tubes. Did Scott count the limiting capability of the ratio detector as the 3rd limiting stage?

Wade Antenna, of Ontario, Canada, provides the J55-FM antenna. It is a 5-element, log periodic antenna. Wade indicates that the antenna is quite robust, and Wade provides full specs. When I contacted Wade, it referred me to its US distributor, Mega Hertz. Mhz told me it only sells to businesses...

I discovered that the lamps and at least some of the tubes of my tuner are lit even when the rectifier tube is pulled. Since the rectifier changes AC to DC, I assume both types of current are used in the tuner. Would someone explain the distribution of current types in a tubed tuner?

From those who experienced it, what was it like?

I was researching the history of EPI and managed to find some facts that are a little different from what some others, such as HUMAN Speakers, have reported. I am setting them out here with sources, so that they are not lost. a. Epi logo first used Mar 10, 1968. Source: Official Gazette of the...

If someone has the owner's manual, what does it say about the use of this switch?

HUMAN Speakers can do either; with shipping the cost is about the same. Of the several tweeter designs over the years, I'm thinking some might be worth saving.

From photos online, the above tuners have no mute switch. Is there automatic muting? I find no schematic online. Did Scott think that muting was unnecessary? The mute on my 312-C is problematic, and I've read the same about the 312-D. Prior tubed models had functioning mute.