Your Oldest Working AM Radio

[trusty]

After looking at pictures of some old 1920's Crosley radios, my son asked me, "What are all the extra knobs for?"
I said, "I forgot, but I know our friends at Radio-Info can help."

So, I appreciate the info AND if you'll share:

What is the oldest working AM radio you have?
How well does it work in today's AM environment?
What extra "knobs" does it have and how do they make a difference in reception & quality?

 

[FreddyE1977]

Mine is not very old by old radio standards. An RCA Victor five-tube bakelite table model from the late 1940's.
Has really excellent sound quality, a rich tone you just can't get even on a lot of FM sets today. Set is very
basic Not very sophisticated, just a single tuning knob on the front (simple dial with a pointer, no string and
pulley gliding pointer or anything) and an on/off volume knob (that one is not original, my father accidentally
broke it while I was living at home). There is also a jack for some sort of turntable attachment that was
apparently available from RCA. Got it from my uncle who bought a house in an estate sale after it's long time
occupant, a 100 year old retired policeman, had passed away. I helped him do some fix-up and painting chores
before he moved his family into it, and he gave me this radio, which came with the house, as a thank-you present.
He had it serviced and re-capped at a local TV repair shop before giving it to me, so the internals are much
newer than the whole thing.

This radio is rather good at tuning distant and weak stations. I used to be able to get some far-fringe
stations from 150-180 miles away during daylight hours. Unfortunately some of my locals running IBOC
has screwed this up for me. One drawback is that this radio seems to be unusually sensitive in picking
up harmonics from strong local stations.

I own a 1939 Philco portable which my wife bought for me on Ebay, but it is not in working order
(and would require someone with far greater electronic skills than I have to make it so)

 

[K6JHU]

Thank Major Armstrong, inventor of FM. H also invented the "Superheterodyne", also knwn as "Superhet". Basis of all modern radios. Before that time the best you could do was "Tuned Radio Frequency" or TRF. That is what you see with all the knobs.

The name TRF tells you why all the knobs were there without going into details. There were several stages of RF amplification and each stage had to be adjusted separately for best reception. Overtune and it went into oscillation (the squal you hear when tuning an old radio). So there was a knob for each stage.

"Superhet" solved that problem (without going into details) using a "trick" by generating a fixed "Intermediate Frequency" (IF) that is independant of the tuned frequency. That means that fixed stages of amplification could be designed that did not require tuning. Then all the extra knobs disappeared.

So fewer knobs (one tuning and one audio) and a radio that actually performed better. TRF bit the dust.

 

[Darth_vader]

I have a late-1940s Crosley radio that I inherited from my Grampa few years back after he died. There's some sort of "line-out" that someone worked onto it at some point way back in history, but it consists of two screw termnials with "OUT +" and "OUT -" scratched into the metal back plate right above. When I last heard the radio about four years ago it sounded very beautiful, especially on a clear transmission (like KKAD.) Thankfully MW IBAC transmissions are few in this market. KEX sounds awful on this rig, as it does on virtually any other MW AM rig.

I haven't gotten it working since I brought it home. The box it was in was dropped on the ground in a move, and two of the tubes broke in the process and are now gassy. They do get nice and hot, but there's no sound. I do intend to replace them some day.

"There is also a jack for some sort of turntable attachment that was apparently available from RCA."

And that's why the jacks on the back of stereo receivers to this day are known as "RCA jacks".