The 35-position "MHz Select" knob also controls a motorized eleven band preselector.

Dating the national hro comments on the truth about internet dating

A unique feature of the HRO-600 is its plug-in frequency control options.

Shown here is the Model 601 tunable VFO module, which features a four-digit Nixie tube display.

Included was a nice Hallicrafters SX28A (god these are heavy). How can these things be dated and where can I find info about this model? I'm pretty sure that mine is an HRO "Junior".cheersps : lemme know if you'd like a picture------------------John Bartley43 Norway Spruce Street Stittsville, Ontario Canada, K2S1P5-----If you slow down it takes longer,- does that apply to life also? It would come on and go off at precisely 60 second intervals! By the way do you know how the HRO series was named?

But also included in a NC set that has plug front panel tuning cans. Folklore states that when Jim Millen was pushing for it, suddenly orders came in the door for it and they didn't have product to ship.

THE NATIONAL RADIO COMPANY launched its legendary "HRO" series of communications receivers in 1935 with the 9 tube single-conversion HRO.

After 40 years, the HRO dynasty finally ended with the solid state, synthesized HRO-600, pictured at the right.

Intended primarily for government and commercial users, and priced at 00, the HRO-600 is today rarely seen.

(Reportedly, fewer than than two hundred were manufactured.) The HRO-600 was introduced in 1970, shortly after National declared bankruptcy.

Most of the radio's circuitry is housed on vertically mounted plug-in printed circuit modules.

Moving from left to right at the rear are the "front end module," the "1st injection synthesizer module," the "2nd mixer module," the "2nd injection/AF amplifier module," and the power supply regulator and filter capacitor modules.

The frequency stability is specified (with the 601 plug-in VFO) as less than a 20 Hz drift in 15 minutes.