Sound of AM back in 60s and 70s

[davideduardo]

Well, CKLW was (and is) DA-2 with a five-tower array while WJR's a 1-A, NDA unlimited. CK had to protect, among others, Thunder Bay, Belleville, etc., so it's not surprising 760 was better towards Grand Rapids. The CKLW pattern was designed to be pretty much a local signal in Detroit, Toledo and Cleveland - and it was, back in the day. We routinely gave temp readings for the three cities.

CKLW mostly protected the "owner" of the channel, XELO in Cd. Juárez, at night. All Canadian 800's, including Moose Jaw and others, shot away from Mexico and XELO at night. There were also a fair number of 790's in the US that CKLW had to protect as well as the rather large protected contour of WBBM in Chicago... perhaps the more likely reason for Grand Rapids being in a lesser signal area.

The CKLW pattern was designed to protect Mexico at night, and all the co-channel Canadian stations as well as the adjacents. The coverage it had was a result of sending the signal towards whatever areas were left. If the station had been designed for best performance, lower Michigan, NW Ohio and NE Indiana would be a desirable market area. Cleveland, a major metro of its own, would not.

CKLW was often thought to have had much bigger Cleveland numbers than fact supports. While the western suburbs like Parma got a pretty decent signal, most of the metro did not.

 

[Schroedingers Cat]

It's interesting that WSGW Saginaw, MI nearly overlaps WBBM in Chicago. You'd never expect that. Some people have reported hearing WSGW in Chicago on the east side of tall buildings in Chicago, both day and night. I have personally tuned it in near Racine, WI with no problem. WSGW also has a lot of overlap with CKLW. WBBM and CKLW are the primary contributors to WSGW's NIF contour. Until IBOC on WBBM, WSGW had a much better signal than the NIF would indicate.

David, I'd forgotten the old XELO call letters until you mentioned them. I heard XEROK back in the 1970s, especially when CKLW was off the air. Now that PJB uses less power and a directional antenna, CKLW's signal is much better at night.

I've often wondered when people reported hearing CKLW and WCFL/WMVP in California, if they were on day pattern.

For much of the pattern to the north and west and south at night, CKLW is on the order of a 5 kW station.

 

[bossbill]

The old receivers were very broadband.

 

[Schroedingers Cat]

Often too broadband, Bill, at the expense of selectivity. I would have preferred a radio back then with a wide/narrow IF switch for the best of both worlds.

Too often a strong local signal would blot out anything up to 30 kHz either side of the carrier frequency. Oh wait, that's true with IBOC even with a narrow band setting!

To the person with the WGLI in their screen name, is that a reference to the Babylon, NY station on 1290 that no longer exists due to WADO's upgrade to 50 kW daytime? If so, did you know Bill Lee and family who worked for the Beck Ross Group? Great radio people who enhanced communities wherever they went!

 

[rfry]

For much of the pattern to the north and west and south at night, CKLW is on the order of a 5 kW station

Focusing on the Grand Rapids area, the ~148-mile, great circle path from CKLW to the GRR airport lies on about the 295-degree radial from the CKLW site. Interestingly, that path passes very close to the WJR transmitter site.

The data from the FCC website for the daytime, theoretical field of CKLW shows about 768 mV/m at 1 km on their 295-degree radial, for 50 kW of applied power. As CKLW uses 88-degree verticals, this means that if all of their power was radiated by a single, series-fed, 88-degree monopole with a 2-ohm connection to r-f ground, that radiator would need about 6.34 kW of Z-matched power applied to it.

The bottom of the null from CKLW to the NW occurs at 320 degrees, and produces an IDF of 534 mV/m at 1 km for 50 kW. The power needed by the above, single radiator to produce that field at 1 km is about 3.07 kW. So the ~5kW stated by Schroedingers Cat is in good agreement with their average ERP in that sector.

Continuing with their comparison to WJR, CKLW would need to apply about 87 kW to that hypothetical, single 88-degree radiator in order to produce the 2,848 mV/m IDF at 1 km generated toward that NW sector by the facilities of WJR.

RF

 

[Boardengineer12]

When I first broke into commerical radio in 1979, at WNBC we were using an RCA BTA50H (ampliphase) transmitter as our main transmitter; really didn't modulate all that well. Our backup was an RCA BTA5A which likewise didn't do much for the sound of the station; I think it topped out at 75% pos peaks. For those of us assigned to the transmitter, it was not unusual to have the transmitter dump off during your shift at least once or twice.

Then in 1981 or 82 we bought and installed a Harris MW-50 which I believed was pulse modulated; talk about an improvement in audio quality over the airwaves! It ran circles around the RCA transmitter equipment. then 2 years later, we purchased a new Continental 317 (Doherty modulated). I recall that Mike Bock, the transmitter supervisor had a pic of the Continental hung up in his office with arch marks penned into the picture as the 317 had problems with arching off the finals and onto the case of the transmitter (Continental has fixed this problem by the time we had purchased the transmitter) which was done to bust Bill Krause's chops (Director of engineering). But it was an amazing transmitter; I think to this day its still in service at the 'FAN (WFAN). It really had a great sound to it; still does for that matter.

 

[wgliradio]

The 317 is still the aux, removed from service by a DX-50, which is still the main. The MW-50 went to Chicago IIRC and the 5A was replaced by a Gates FIVE when both the WCBS and WFAN antenna systems were rebuilt about 8-9 years ago which included replacement of the aux tower in the flood plain with a new tower and tuning house that were raised up off the ground.

 

[kenglish]

I had a mentor named Charles McHan back in the 60's, when I was in high school. It's said he can make AM sound great. He's currently building these:

http://www.vintageloop.com/vintageloop/pureanalogdualevel.html

There used to be some samples and video available on the web, but I'm having trouble locating them right now.

 

[Boardengineer12]

The 317 is still the aux, removed from service by a DX-50, which is still the main. The MW-50 went to Chicago IIRC and the 5A was replaced by a Gates FIVE when both the WCBS and WFAN antenna systems were rebuilt about 8-9 years ago which included replacement of the aux tower in the flood plain with a new tower and tuning house that were raised up off the ground.

Does WFAN/WCBS still have problems with poachers swiping the grounding radials? It was a problem for us as they went after the copper wire; one time we had just installed brand new radials and wouldn't you guess the very next day when we came back, we found out they'd cut over half of them out on us.

 

[kenglish]

The 317 is still the aux, removed from service by a DX-50, which is still the main. The MW-50 went to Chicago IIRC and the 5A was replaced by a Gates FIVE when both the WCBS and WFAN antenna systems were rebuilt about 8-9 years ago which included replacement of the aux tower in the flood plain with a new tower and tuning house that were raised up off the ground.

Does WFAN/WCBS still have problems with poachers swiping the grounding radials? It was a problem for us as they went after the copper wire; one time we had just installed brand new radials and wouldn't you guess the very next day when we came back, we found out they'd cut over half of them out on us.

You didn't warn the crooks about "the RADIATION' those things have? ;D

 

[Boardengineer12]

Does WFAN/WCBS still have problems with poachers swiping the grounding radials? It was a problem for us as they went after the copper wire; one time we had just installed brand new radials and wouldn't you guess the very next day when we came back, we found out they'd cut over half of them out on us.

You didn't warn the crooks about "the RADIATION' those things have? ;D

We never found any irradiated bodies wash up on High Island, but once one of our engineers found burned clothing in the Aux tuning house; some had apprently entered the tuning house from the roof and must have touched one of the coils and gotten rapped.

 

[robgrayson]

I am hoping you can tell somthing from this snippet of audio... I have always referenced any radio processing, in my own mind, with what they were dong at WJDX, Jackson, MS, back in the mid-70's. This is a clip from a skimmer tape, presumably from the mod monitor in the control room.
http://www.facebook.com/profile.php?id=1339114489&v=app_2392950137#!/video/video.php?v=1514052894812

 

[robgrayson]

Sorry, I thought the link above would send you to the posted audio. If you aren't facebook-friendly, PM me and I will send you the clip.

 

[Ai4i]

Speaking of 800 KHz, were there ever any negotians with the Dutch Antilotians regarding PJB?
I grew up on Miami Beach and their half megawatt night signal came in as well as WFUN on 790.

 

[gr8oldies]

No, PJB just poached.

 

[Steve Eberhart]

a CBS Audimax / Volumax made broadband radio sound awesome as long as you adjusted the attack and release time, which most Top 40 stations figured out.

The Dorrough DAP 310 was also a step ahead, sounded awesome - as long as the audio was kept in the "sweet zone"...if you ran it by itself, the audio had no punch at times. The best sound using the DAP 310 included putting a simple compressor/limiter like a little Marti CLA-40 in front of it to keep it working the sweet zone.
That gave it clarity unknown before that plus punch.

 

[ajaynejr]

I remember AM sounding better in the 60s and 70s. There were still plenty of 5 tube AM radios still around. Car radios pre 64-65 were tube instead of solid state. I bet Fisher and Scott tuners of the 60s had good sounding AM sections. Did not AM stations tried to proof from 100-7500 Hz freqency response back then?

Didn't a lot of folks turn the tone control of their car radio or 5 tube table radio "all the way down" in an effort to get "extra bass" and therefore not hear the difference between a 7500 Hz versus a 5000 Hz broadcast frequency response?

 

[Chuck]

I remember AM sounding better in the 60s and 70s. There were still plenty of 5 tube AM radios still around. Car radios pre 64-65 were tube instead of solid state. I bet Fisher and Scott tuners of the 60s had good sounding AM sections. Did not AM stations tried to proof from 100-7500 Hz freqency response back then?

Didn't a lot of folks turn the tone control of their car radio or 5 tube table radio "all the way down" in an effort to get "extra bass" and therefore not hear the difference between a 7500 Hz versus a 5000 Hz broadcast frequency response?

I don't remember that in the 1960's when AM ruled. In fact my recollection is turning the tone control up about 3/4 of the way to get more highs on a '66 Mustang radio.

 

[Ai4i]

The cheapest and most common "tone" controls were only trebble cuts. They did not affect the base, just reduced the high mid-range. Many were labled "music" (CCW) and "voice" (CW).

 

[rorban]

I don't remember that in the 1960's when AM ruled. In fact my recollection is turning the tone control up about 3/4 of the way to get more highs on a '66 Mustang radio.

I think many people tuned the radio slightly off-center to get more highs. (This was the era of continous tunig, after all). Because the highs on many stations were not boosted and because IF slopes were mostly gentle (this was also before horrible-sounding ceramic filters were introduced in the IFs), tuning the radio off-center did not create too much objectionable distortion in envelope detectors, although there was certainly some.

Bob Orban