1980s AM Stereo Radio, 1980s AM Stereo Station

Hi Bruce MICRO1700

Here is a paragraph answering part of your question

As of December 2009[update], there are still several AM radio stations in North America broadcasting in C-QUAM stereo. Among those stations are WWBF 1330 kHz, Bartow, Florida; CFCO 630 kHz Chatham, Ontario (covering SW Ontario, Eastern Michigan and Northern Ohio); KCJJ 1630 kHz, Iowa City, Iowa (covering Iowa and several states at night); WLS 890 kHz during night hours, Chicago, Illinois; WNMB 900 kHz, North Myrtle Beach, South Carolina; WXNI 1230 kHz, Westerly, Rhode Island; WREF, Ridgefield, Connecticut; and WLAD, Danbury, Connecticut. In addition to FCC-Licensed C-QUAM AM broadcast stations, low-powered (<100mW) Part 15 C-QUAM stereo transmitters are available for sale for use in the United States. In Rome, Italy, there is Broadcastitalia on 1485 kHz.

I copied that from Wikipedia, where you can Search C-QUAM for a good read about the subject.

Now I've found a Part 15 station in C-QUAM

http://www.mixutah.com/faq.htm

The Crow might want to check to see if this one is mapped.

I'll have to try those Connecticut stations you
mentioned.

WREF on 850 is too weak, but I might be able
to pull WLAD on 800 out of the noise.

You mentioned KCJJ on 1630. I used to be
able to get them, but they are covered up by
a TIS station that is just down my street!

I couldn't open up the link you mentioned
about the Part 15 station, but that's OK.
Maybe it's a problem with this computer.

I'll also check WLS.

Thanks Carl, it's good to have an updated
list that is only 2 years old. The most recent
list I could find was from 2007.

Thanks again and best wishes!

Bruce, MICRO1690/1700

BRUCE that link I put with the faq.htm didn't work when I tried it either

But this worked

http://mixutah.com/

I will be running a BE AX-10 (I have two) into a cunningham CM20-50 for Cquam using his universal tuner to couple it to the power lines.

I also have a chris cuff/AL unit and a panasonic VP series multi am stereo transmitter /sig gen all of which is not for sale

i also have a Delta ASE2 which is for sale and can be seen in the FS/FT forum

Hi There KC8GPD!

Now I remember where and when I started
thinking about AM stereo. That was about
the same time I dragged out the SRF-A100
and started listening around.

It started when I read your original post about
your for-sale Delta Electronics ASE2! (I wish
I could buy it but I can't unfortunately.)

I think that was about the same time you posted
the pictures of your studio. (Which everybody loves
by the way.)

Best Wishes,
Bruce, MICRO1690/1700

P.S. I think it's wonderful that you are keeping
the old AM stereo mode alive!

My carrier current station is in AM stereo and I have two transmitters, one on air and one stand by. The first uses the C-CUFF C-QUAM exciter board in place of the LPB mono exciter board. Both boards are the same physical dimensions so the C-CUFF board mounts nicely and drives the PA amp perfectly with a very clean AM stereo signal.

The second LPB unit uses the ASMAX-1 C-QUAM exciter and serves as the backup transmitter. This second LPB unit has another special modification on the final amplifier filter. I replaced the solder studs with board mount relay sockets so I can change out the low pass filter components to allow for full band coverage and proper filtering.

Most HD radios are capable of decoding the C-QUAM stereo signal. I like to watch people listening to my station and in disbelief that they are tuned to an AM station and hearing it in rich full stereo sound!

I even prefer to have the off air monitor system running the AM stereo receiver rather than the FM stereo receiver...simply because it has a warmer, smoother sound.

Long live AM Stereo!!!!

RFB

I just received an email from the one and only Chris Cuff, designer of the infamous C-Cuff AM Stereo transmitter. He is offering his unit in kit form now on ebay at

http://cgi.ebay.com/AM-Stereo-Transmitter-CQUAM-DIY-Kit-Assembled-avail-/320657584082?pt=LH_DefaultDomain_0&hash=item4aa8ae6fd2

He also has a video on youtube regarding his unit..

If you want to go stereo, NOW is your chance to grab one of these excellent units at a very cheap price! There is no simpler way to go full AM stereo than using one of the C-Cuff C-QUAM exciters.

I use them in my LPB TX 2-20 and AM-25 transmitters in place of the mono LPB exciter and they work flawlessly.

These can come with or without the high power RF final stage. I recommend you get one WITH the power stage and make minor changes to the final circuit to keep with the 100mW specification. Without the power stage, the exciter unit only outputs about 50mW but is still useful even with that lower power input.

In any case...NOW IS THE TIME!!! And there is NO cheaper way than this to turn your station into a true AM C-QUAM Stereo station!

Trust me...once you hear your station blasting out in stereo on AM, you will NEVER go back to mono again. But for those who absolutely refuse to move into the modern era...its very easy to add a stereo/mono switch to these boards. :p

RFB

Thanks for the info. I'm glad to see
Chris is still out there.

I can't afford the transmitter right now,
but there is the future...

Thanks again!

Bruce,
MR1.69/1.7

Thanks for the info. I'm glad to see
Chris is still out there.

Indeed. I keep regular contact with him and for awhile he was going to throw in the towel for good on these. However he has decided to provide these in "kit" form along with the "assembled" version. If all goes well, he will continue to make them available.

I can't afford the transmitter right now,
but there is the future...

I understand that. I had purchased 4 of these units assembled and 2 in un-assembled form last year so as to have enough spares around. Back then they were more expensive. Hopefully you can grab one of these soon and go stereo. You can also get the programmable oscillator to replace the crystal, which is cheaper than ordering a custom crystal for your operating frequency. These can be obtained from Digi-Key for about 8 bucks each.

These units produce a very clean and uniform envelope as is. But when you examine the schematic, you can easily add adjustment pots to peak the envelope performance as well as the L+R/L-R mux balancing.

For those who own LPB TX carrier current series, these make excellent replacement exciters and mount perfectly as both the mono LPB exciter board and the C-Cuff C-QUAM board are the same dimensions. The C-Cuff board can be powered by the LPB's 15 volt rail and the RF coax connected directly to the board's antenna output for the amplifier.

In fact, using the C-Cuff board eliminates that annoying stray capacitance issue that plagued the LPB exciter board...mostly because the LPB exciter board used those bulky stand-up pots and the one used to adjust the exciter RF output is incredibly sensitive to stray inductance which could make your unit's RF power run wild trying to adjust it while turned on.

The C-Cuff board also uses less current and helps the entire LPB transmitter to run cooler.

As stated before..they make excellent Part 15 219 transmitters by itself and beats all the other units out there regarding spectral purity. Easy to maintain and adjust as well as add metering on the final, you can readily demonstrate that the unit is not exceeding the Part 15 limits.

RFB

Wow! Good for you! I like to have items
in duplicate, too - for redundancy.

Do you (or does anybody else) have experience
with transmitter range? For instance -
has anybody ever put one of these transmitters
outside - ground mounted - with a loading coil
and 3 meter stick? And has anybody checked
the range of a set-up like this?

Also, I'm glad Chris decided to keep making these
transmitters. I'm sure it isn't easy. But there
are some of us who are very interested in this
mode of AM stereo transmission.

Best Wishes,
Bruce, MICRO1690/1700

Howdy Bruce!

Do you (or does anybody else) have experience
with transmitter range? For instance -
has anybody ever put one of these transmitters
outside - ground mounted - with a loading coil
and 3 meter stick? And has anybody checked
the range of a set-up like this?

Yes, I have one currently set up on a 3 meter setup serving as a 3rd backup to my CC setup. It performs just as well as the infamous Rangemaster.

Range is a result of how good the antenna and ground system is built and maintained and tuned...not the TX. I have a Rangemaster and a Procaster and have tested both of these on my antenna system as well as testing the C-Cuff board on that same antenna system. All 3 have the same range results.

The only unit I have not tested is an SSTran. However its really mute because all of the units are set for meeting the power limit, thus they all will put the same amount of RF onto the antenna system. It is the antenna system that determines the range.

So if you have a well built and tuned 3 meter antenna system, you can install one of these C-Cuff boards and not notice any change in range, only change that will take place is your sending out a stereo signal, and sending out a stereo signal on AM does not affect range like that on FM with a stereo signal.

RFB

Yup, range on a C-Quam signal does not
effect the stereo signal. You may have
read this, but the one C-Quam stereo
signal I can get here is very weak. But
the stereo is still there.

Bruce, MICRO1690/1700

It is really sad what the FCC did back in the 80's regarding AM stereo. Quite simply it was a very stupid mistake on the FCC's part.

To "let the market decide" on the standard to use is what killed the prospects of AM stereo in the USA. But here is the real kicker to that. Did the FCC or anyone else do any public education and demonstration in the US?

Nope. And you cannot count the NAB conventions back then demonstrating AM stereo as educating the public. The mass public did not attend nor to this day attends the NAB conventions.

How the heck is the market to decide on something if it is not told what that something is???

While the US was fiddle farting around...other countries were already enjoying the rich stereo sound on AM and most were using the Motorola C-QUAM system. But here in the US...there were at least 3 different systems being bandied about, none of which besides the C-QUAM were mono receiver compatible. How ironic to flood the industry with non-compatible transmissions. All it did was create confusion and refusal by receiver manufacturers to not include ANY stereo decoding ability because of the costs.

Well mistakes of the past do not have to be repeated since the FCC in 1992 finally got off their duff and declared the Motorola C-QUAM to be the standard. Heck by that time...AM stereo concept in the US was like looking at an ancient scroll barely readable and missing large chunks of the writing.

Now that most HD radios include the C-QUAM decoder, it is a perfect time to rejuvinate the AM stereo concept in the US. And with the headache that licensed broadcasters went through back then..they are not likely to jump on board and start installing new C-QUAM exciters or bother to even flip the stereo switch on their existing aged C-QUAM exciters or reconfigure the studios for it as well as STL linking.

It will be up to the Part 15 community to revitalize the AM stereo concept in the US. I for one am fully behind it and will always run my AM station in full glory C-QUAM stereo!

RFB