Harris AMS-G1 C-Quam AM Stereo exciter
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- เผยแพร่เมื่อ 9 ก.พ. 2025
- A review and test of the Harris AMS-G1, an AM Stereo exciter/generator using the Motorola C-Quam system, introduced in 1994. This one was purchased from 1630 KCJJ when they discontinued AM Stereo operation a few years ago.
Data sheet: bh.hallikainen....
Wow, does this take me back! I was the designer of this unit, and I haven't seen one in over 20 years. Thanks for posting this! It was indeed a unique design, with some tweaks to the equalization circuitry that allowed you to set up one of these in about 1/4 the time of any other AM stereo exciter of its time.
Thanks for the comment! I just wish more stations which still have C-Quam exciters would actually use them...
BTW, do you still have any crystals for the AMS-G1? I would like to change mine to a different frequency, but I just contacted Harris (now known as GatesAir) and they told me they no longer have any crystals available for it.
@@vwestlife Check with Quartslab.com in the UK....ICM quality and free shipping
@@vwestlife Did you end up finding any more crystals? Motorola not being able to supply shouldn't be a problem, you could order them from any crystal supply house once you know the specs. GatesAir should be able to tell you what those specs are.
I wish AM stereo had existed over here, it would have been interesting to hear AM not sounding like a telephone for once.
+CoolDudeClem A few stations in Europe are transmitting in AM Stereo, including France Bleu from Paris on 864 kHz, which can be heard in the southern part of the UK, especially at night.
+vwestlife I think might have picked that up once or twice (although in mono) on some of my experimental radio circuits, it wouldn't surprise me if I did.
+lizichell2 Actually I measured one of the AM music stations that CoolDudeClem played in his videos as having an audio bandwidth of around 7.5 to 8 kHz. But the stations in continental Europe use a narrower bandwidth because the Mediumwave band is more crowded there.
The PDM sample is used to correct for the power amplifier non-linearity in SX series transmitters (Known to some engineers and the 'sucks' series). It takes a sample of the PA voltage from the modulator and pre-distorts the RF drive with a variable phase term to cancel the IPM of the transmitter. Without this correction, it was difficult, if not impossible to get acceptable distortion and separation figures from some of these boxes. Later transmitters from most manufacturers included IPM correction circuitry to make them 'stereo ready'. This became even more important with the introduction of various digital modulation methods like IBOC and DRM.
Sounds fantastic. I built a C-Quam transmitter a yew years back, 400mW on full power and it sounds great too.
I never knew AM Stereo sounded this good. I don't think I had anything that play AM Stereo. I have heard AM HD Radio and I was impressed, but this being an analog format sound really good.
I worked at a station that bought one of these along with a Harris DX-50 50,000 watt AM transmitter (KWJJ-AM, Portland Ore). When they were all set up, they produced excellent AM stereo (like better then 50DB channel to channel separation out the antenna). Glad to see one of these again, thanks for posting! Now someone correct me if I am wrong but the PDM sample plug on the back of that unit was actually supposed to receive a sample of the PDM (Pulse Duration Modulation) signal used in the transmitter (assuming you were running a PDM style transmitter). The AM stereo generator would use this signal to compensate for and cancel out the Miller Effect of the MOSFETS in the transmitter, allowing substantially better stereo separation when using a PDM transmitter. It's been many years since I have seen one of these units, but as I recall this is the only AM stereo generator that I saw that had this PDM correction circuitry. Good Job Harris. They made some excellent AM equipment in those days.
AM stereo sounded great way back then until the NRSC mask was implemented reducing AM's audio frequency response. The FCC's AM revitalization plan comes a day late and a dollar short. Excellent find and review vwestlife!. I really enjoy the stuff you find and do a piece on it. Keep up the great work!!!
I'm happy to see those Phoenix connectors on the back, I wish the TVS-3001 had those! Every time I hear an AM Stereo recording, I'm impressed, I hope to hear AM stereo in real life at some point!
+weasel2htm uxwbill should let you listen to his Chris Cuff transmitter and his various AM Stereo tuners the next time you're over.
I was going to say "you should totally install Linux on that", only the bug makes me think someone already did! Okay, I'm a bad person and I'll go home now. :-P
The audio quality and separation are both striking. Those removable connectors blocks are also commonly seen on alarm panels, building management stuff and devices that support dry contact/trigger inputs.
+uxwbill Harris's HD Radio IBOC exciters actually do run on Linux -- and yes, I have heard stories about them crashing.
I haven't examined the schematic closely, so there might be a small microcontroller hiding in it somewhere, but as far as I know, the AMS-G1 is all analog.
Most AM stations here in DFW Texas don't come through very well. Wow this thing puts out some very clear and crisp audio in my opinion. Thank you for showing it to us.
Very cool. I've listened to KCJJ since the 90's (its an easy catch in Texas - they have a huge signal for 1K at night) and probably heard this exciter/generator being used. Their processing sounded great so its kind of a shame they dropped AM stereo. I heard WLS 890 is running AM Stereo now, but it doesn't make a huge difference since its a talk format.
I love the musical version of War Of The Worlds, my dad bought it on CD when I was very young and it scared the hell out of me but it had some good music and a pretty good rendition of the story.
Those "Pluggable Terminal Blocks" or "Phoenix Connectors" are actually very common in audio applications for mic and line level inputs to professional grade exciters and PA amplifiers intended for 25, 70, or 100 volt permanent installations.
They are far from unusual if you work in the professional radio and audio field.
Harris is a good brand, now they are partnered with Ma-Com (General Electric / Ericson), we bought all Harris 700MHz OpenSky equipment to be compatible with the Ma-Com OpenSky system in Las Vegas.
+ElfNet Gaming I agree, my 100V PA amplifiers also have these connectors on the output, except they are green, not orange like in this video.
Yeah green is the norm, I have seen replacements of various colors though
In the '80s the FCC extended the AM band from 1600 to 1700kHz, and mandated every station there had to be stereo. They let the other stations decide whether or not to use it, and of course, most didn't. I used to get KCJJ at night, great signal.
5 Rounds YEP and some of them simply broadcast the pilot signal only so they could continue being oN that 1600-1700 kHz slice of the AM BC band.
The quality of the signal is very good!
A lot of those songs remind me of our local radio station.
They play a bit of new songs, and lots of the classics like those.
You know, for a long time I wondered why you guys shout so much about AM Stereo being wonderful. When I first heard it at its best I instantly understood why.
You know a lot more about this stuff then I do, that's for sure. Thanks for sharing.
That front panel solution with the plastic decal reminds me my RE Instruments RE532 RDS encoder, which was made roughly in the same era.
Im in love with your videos, Started watching then at 11am, then another, after another and what do you know. Its 6pm and I still cant stop watching them. Im just extremely interested in all your videos and there content. :)
Loving your videos :) Electronics are cool
Hello Kevin! i want to wish you and your family a happy Christmas and a happy New year, i hope you get an amazing time tomorrow
I love your enthusiasm for all things electronic :-)
That sounds really good... like FM, but with a nice warm tone, and without all the clipping, distortion, and brightness (which is a shame, since FM has potential to sound fantastic when the audio processors are set correctly!). With my TM-152, I've noticed how different radio stations have different bandwidths; most of them are about average, but the local country station has the widest bandwidth I've ever heard on AM. Also, that bug in there is a maple bug. Saskatchewan is crawling with them, especially in the country. I've seen entire walls covered with them! Also, I hope the snake didn't bite you when you opened the unit. :-P
Don’t need a terminator on the output to impedance match?
Great look at this; I was always curious about AM stereo generation. But, something is nagging at me -- how is this video up on youtube without any copyright redirects/takedowns?
Music clips of 28 seconds or less usually will not result in any Content ID copyright matches. So, while editing the video I was very careful to stay within that limit. :-)
+vwestlife War of the worlds. One of my favorite's all time..
0:01 .... War Of The Worlds!!!!! They used this as a BGM in the American Sailor Moon series and it was also sampled in the beat for "Blaze" by the Rap Group "Arsonists."
Very good sound! Seems to be made up from off the shelf ICs. I recall the AM stereo in the '91 GMC Jimmy we had. For some reason the sports / talk station went AM stereo. I remember the stereo imaging of the beer commercials ;)
11:03 "I Like this sticker, remove all power before servicing or else a snake will bite you." lmfao subbed!
Thank You for your videos. When I was a kid my brother and I received for Christmas the Sony FM-AM Stereo SRF-A1 portable radio. It still works well but not sure if there are any AM stations broadcasting in stereo anymore. I lived in Thunder Bay, Ontario and enjoyed listening to WLS 890 in Chicago (when they used to play music). I'm really interested in the AM stereo exciter you showed here. It's fascinating to learn how it works. Right now I'm looking for a digital am stereo receiver but they are getting harder to find.
If that were a real AM station I would totally listen to that playlist.
Those connectors are “Phoenix” or “euro block” connectors and are super common in the professional audio world.
I have no idea what you're talking about, but I like your editing and voice... :3
Have an STX-1B Harris AMS exciter, set to 930khz. Mine doesn't appear to have any way to monitor a stereo transmission at all. It has a 4 watt RF output, but even though it all looks operational left and right, I'm only getting left (I think) audio coming across both channels on my C-Quam radio. Seems like I should have at least a real summed mono signal on my radio. Size-wise, the exciter is huge. About like a Pioneer RT-707 reel to reel.
listening to the audio samples at the end, that's pretty good for AM
Lucky fer I'd love to have one, thanks for sharing
Wow! It's this real? What a relic!
How exciting.
AM (medium wave) here in the UK remained resolutely mono and poor quality - there was no such thing as “AM stereo” over here - Radio 1 - the BBC’s national broadcaster of the latest chart music - largely was in mono, except when Radio 2 allowed them to play with it - a rare treat - 10 pm to midnight on weeknights for John Peel Monday to Thursday and The Friday Rock Show with Tommy Vance on Fridays, Saturdays between 1 pm and 7:30 and Sundays between 5 pm and midnight - but it was mostly on AM, which didn’t do justice to the music of the time! Probably why it’s closed down - no attempt to improve reception, other than moving stations around!
That is one nice looking linear power supply over in the left hand side.
I am curious about the CPR instructions at 3:31.....
What's the range on that? I assume extremely short since you didn't use your Denon receiver for the audio demo?
The range of the Quam Ref Out is just a few feet.
This is kind of an unrelated question, but what are the names of all the records you played during the Jensen JTA-230 record player review? I was wondering because I like the records you played during that video especially the old 78 rpm records from the 1920s/1930s. :)
I think the bug died because of the EM produced in there!
Pitty AM stereo never made it as a standard here in Europe. 25,6 kHz pilot is way better than 19 kHz used in FM. You'd get a better stereo separation and can get sounds as high as 20 kHz. So this must be better than digital radio.Analog uncompressed stereo sound at lower broadcastfrequencies and with a wider spread. Shame to standard makers!
The C-Quam AM Stereo pilot tone is actually 25 Hz, not kHz. It's a sub-audible tone in the L-R component, which the receiver filters out.
How high on the frequency audio band did AM Stereo get up to. It sounds a whole lot further than plain AM Mono.
Excellent video
Because it is difficult to keep Am Stereo?
the Am Stereo improvement to the mono sound?
Because broadcasters turn off, the Am Stereo?
Do you have a CD-4 quad decoder and something with a 24-bit DAC for output? I have a couple of Quadradiscs and was kind of curious about whether a high-res audio of the output from a decent turntable but without the Shibata stylus would decode.
No, I don't have a CD-4 decoder, although you can kinda do it with software on a computer. See my video about CD-4 quadraphonic, if you haven't already.
+vwestlife I left this on the wrong video. I thought if you had been looking into CD-4 for a while, you might've found a decoder.
Very kewl indeed!!
Where did you get that japanese Sony Radio from?
Sounds very nice
Is that case its in made of aluminium ? It looks like it may be but not sure.
Yes, and it is very light -- the whole thing only weighs 8 lbs. (3.6 kg)!
Not meaning to pry, I have on and off shaky hands which I worry a bit about sometimes. Are you alright? I noticed hand tremors.
My hands are fine. My camera's electronic image stabilization sometimes goes strange and unstabilizes the image.
a question if i may. how do you find these items and do you put them in your own stations audio chain, or do you get rid of them after awhile ? thanks
I purchased this one from a radio station which had discontinued broadcasting in AM Stereo. I use it for testing AM Stereo receivers.
:) thanks for answering
Are there any disadvantages of AM stereo? Why many radio stations that broadcast in AM stereo reverted back to mono? AM stereo transmission is backward compatible with mono receivers so despite lack of availability of AM stereo receivers they don't have to revert back to mono.
+bobskie321 Read all about it:
en.wikipedia.org/wiki/AM_stereo
+vwestlife
Thanks for the link which explained that AM stereo is incompatible with HD Radio (both can't be use simultaneously) so they sacrificed AM stereo in favor with HD Radio.
I can only think of lightning static that can cause stereo dropouts.
WION in Ionia, Mi. broadcasts in AM Stereo. 1430 on the dial. I listen in Ky. via their internet stream which they send through a Carver tx-11a. AM stereo tuner.They say it's the actual sound you would hear off air. Pictures on their website
www.i1430.com best variety of music than any station I've heard. IMO. High Fidelity Sound.
WOW, i did'nt Know that you listened to the Norwegian Artist Bjørn Johan Muri With the song Yes Man
I wasn't aware that stereo could be played through an AM setup..
You need a receiver that is capable of detecting and demodulating the stereo information. A normal AM receiver can't do that unless it has a decoder board fitted. A normal AM receiver just demodulates the mono information and ignores the stereo component.
Where can I get one? Seriously...
The voice at the start sounds like the voice at the beginning of iron maidens 'number of the beast'
lol, it's Richard Burton in Jeff Wayne's musical version of War of the Worlds
Where can i found the complete service manual with schematics? Can you uploaded?
I downloaded it from Harris's web site. (They are now known as Gates Air.) I had to create an account but it was free to do so.
I cant find it.Please if you cant sent it to my email: haris_gr_blue@hotmail.com thanks!
Ca you upload the service manual?
What was that at the very end? Was that HG Wells?
Jeff Wayne - "The Eve of the War", from the musical version of The War of the Worlds.
Awesome stuff.
I'm guessing you erased that bug from the system?
In Germany AM means, the highest frequency is 4 or 5 kHz.
Waiting to see a vid on that MacBook Pro
what do you do with all of the old computers you never use?
I sell or give them away.
+vwestlife lol I'm so jealous of your huge collection... I personally want A Presario or that wierd Cyrix one you built,. they look really cool in your videos
+vwestlife What's the Comming from Mars thing?
Jeff Wayne - "The Eve of the War"
I immediately went on Amazon to by the album. As CD of course and not this MP3 rubbish
WLS 890 is correct in maintaining Am Stereo, even though talk format.
What year was that War of The World's broadcast, broadcaster?
+Mr. Red Bird en.wikipedia.org/wiki/Jeff_Wayne%27s_Musical_Version_of_The_War_of_the_Worlds
+vwestlife Thank you!
That’s from a station I listen to a lot
Aww cute little bug 4:01. Too bad it died inside :)
wow thats even better than RTL Radio Luxemburg on 1440 via Skywave DX (and I thought thas good sound)
I am interested in buying this if you're thinking about selling it.
I may consider selling it, but be aware that it will probably be difficult to change it to a different frequency, as Harris (now known as GatesAir) no longer has any crystals for it, and finding a crystal for the frequency you want to transmit it (times 4) may be very difficult unless you can get a custom one made.
I had a Chrysler car radio with Cquam. To bad the speakers were tiny.
Is this unit for sale?
No, I'm keeping it.
@@vwestlife I’ll ask again in a few years, thanks
Thinking of radio , Does anyone remember the Simpsons ep where Bart did get a Mic letting him speak over AM radio?
it is real are was real , It was sold in the 1980`s.
If you ever find one can you do a review?
Those actually used FM.
Cool.
I remember when AM Stereo came on the scene, it was very cool, then it died....not so cool! But in today's AM radio, with all talk, spanglish and sports, who really cares! Am radio is only good now to do YT videos without getting nasty grams from YT....
There are still many great AM stations that play music, but unfortunately not in all areas.
+vwestlife This is true, during travel I do find great stations, however few and far between and none in my area! Great video as always!
He said rack