Some time ago, someone posted a link to diagrams and instructions to convert an existing monophonic AM receiver to AM stereo using an add-on demodulator circuit built from a kit. If I remember right, they (a PDXRadio user, I believe) did it using a 1970s or 1980s car radio with a tapped IF stage and an 8-track player.

Reason I ask is because I have an early-1980s Panasonic RX5030 boom-box (the stereotypical retro "Ghettoblazta" design) that I take with me when travelling and want to convert to receive Cquam......I already added an SCA demodulator last year and now I want to add a Cquam demodulator to the ensemble. (I often listen to Evergreen RRS via KPBX on that particular rig when I go to Pendleton.)

Does anyone know about this and/or have a link and/or instructions? Or is it by chance floating around in the Archives somewhere and I am possibly just not looking hard enough?

Thanks in advance for any and all help/tech advice..........



(Sidebar~ I have a Sony ICF36 which is also equipped with an SCA demodulator, and when I switch the radio into AM mode and kick the SCA demodulator in, tune it to a station broadcasting Cquam, I can actually get the thing to somehow detect the stereo signal, even making the indicator light glow. [My SCA demodulator is an Elf-2A which I got from Dr. Elving about two years ago. It has an LED which lights up whenever a subcarrier is tuned.] I haven't compiled a list of AM stereo stations I have found with it yet, but I might soon.

NOTE: The radio doesn't actually *receive* AM stereo--it is a mono rig anyways. It only *detects* the subcarrier's presence and indicates as such.)

That would be me!

I'll post the link in a moment.

http://www.brickboard.com/RWD/index.htm?id=864201

Enjoy!

there are boards to do this just look on E-bay also this site in the projects section will tell you about obtaining one of these boards: http://ourworld.compuserve.com/homepages/kevtronics/

I personally had one which used the Motorola MC13028A decoder it worked well but because I did not have solder at the time was not able to fully convert the receiver.

Couple of things to add to that link:

I ended up having to remove the wire for the Force to Mono function and re do it using a relay. With the Diode, the AM Stereo section wasn't kicking in, and the FM Stereo was much weaker.

I removed the diode and the wire to the AM Force to Mono pin, and all was fine and well. I had to figure out another way to achieve a Force to Mono ability for the AM radio.

I ended up using a relay that would turn on when I switched to the AM radio. With the Stereo/Mono switch set to Stereo, it would power the relay by supplying the ground to it. The relay was connected to the AM Force to mono wire in the "normally closed" way. This means that when I wanted to force the radio into mono, flipping the switch would kill power to the relay, which would then pull the needed pin on the AM Stereo decoder to ground.

Also, the voltage that powers the decoder (Section E) is actually source volts, not 8. It gets the full 14 (or so) volts.

I couldn't have done the conversion with out the help I got from Larry Holtz.

I remember reading the data sheet for the MC13028A one of the C-QUAM decoder chips that it will take between about 3 and 12 volts and the board I had required a 9 volt battery to power the thing while getting everything up and running before doing the final soldering.

Thank you!!

My radio is a 9 volts-DC system (six D-cells) or AC power via a built-in transformer and detachable power cord so it looks like I would have the right amount of power. (Works perfectly with my current SCA implementation anyways. Dr. Elving says those demodulator boards can handle anywhere from 3 to 12 VDC if I remember right.)

I may just telephone Chris sometime within next week. I saw his web page http://ourworld.compuserve.com/homepages/kevtronics/ccuff.htm, those wood radios do look kind of swook. Doesn't seem to be a date on the page of when it was last updated, so I have no idea if his E Mail listed on the page is still current or not. I will give it a try tho!!

the E-mail should be current so just give it a try. If you did that SCA mod yourself then adding the AM stereo decoder should be about the same just figure out a way to get power, inject the 455 KHz IF of the receiver normally a filter should work or an IF chip if available and get the thing hooked up to the audio amplifier of the receiver and you should be able to get AM stereo broadcasts.

can i convert a regular am to a hd? imho

most likely no HD Radio requires licensing from Ibiquity and not only that the HD receivers out now are all software defined and they require about as much power as a computer.

> can i convert a regular am to a hd?

I don't think that you can buy a HD decoder IC because of Ibiquity's licensing policy.

And that's a good thing, I think. In many cases, best for closed formats to stay closed, really. That helps stimulate growth and development of other, often more interesting and stable open-source developments like Digital Radio Mondial.

(Just think, it's due in no small part to Micro$oft's arcane closed-source model they have used for years with Windows, that many implementations of Linux have become so popular in recent years!)

On the other hand, you can convert an existing radio to receive broadcasts in the Digital Radio Mondial format, with the aid of a computer (see footnote) and not have to worry about licensing, royalties or any other such un-necessary rot. (I have even seen pages showing how it can be done~ see http://www.drmrx.org/mods/grundig_yacht_boy_400_lowres_1_en.pdf for a mod to a Grundig radio that is extremely similar to one I have, and http://www.drmrx.org/receiver_mods.html for more.)

If Ibiquity had followed that example/model from the beginning, its IBAC system would probably be more popular than I have observed it being currently................

I understand that a DRM system is being made (or maybe it has already been made?) for use on medium-wave. Is there any chance that one may in the future be used in the US?

DRM is primarily medium wave. It's the idea of using it for the FM band that is new. I never heard of it until the IBOC system was established.

DRM is mainly shortwave but there are a few transmitters that target the western United States there is one in Bonaire in the Netherland Antillies, another one in New Zealand, and also Sackville Canada. The catch is that the receiver has to be modified one common way is to add a downmixer to the IF stage what this will do is take the receiver's IF and convert it down to 12 KHz so that it can be patched into a computer soundcard and decoded. This method is used mainly for communications receivers but for this it depends on the receiver for example, with Icom receivers this is done to the 9 MHz IF stage which is in receivers such as the IC-R75 as well as many other receivers and amateur radio transceivers. DRM is used on MW mainly in Europe but there is one site in China that transmits DRM on the MW band.

Semoochie~

Are you sure you aren't thinking of FM-Extra? It's a digital system (actually a true IBOC) that uses the bandwidth where SCA channels would otherwise be located to transmit a digital broadcast.

From what I have read about it, listeners have claimed that FM-Extra is actually of far higher fidelity than the Ibiquity system. The real catch is Fm Extra's channels are broadcast at about the same 10-20% modulation as SCA so receiving it in an outlying area, even if the main channel is clearly audible, might be challenging.

I haven't had an opportunity to listen to it myself (from what I understand the system isn't even being used here yet) so I really can't give any of my own comments on its operation........

Some time ago I alluded to the auxillary channel often broadcast on Ibiquity's system as being a sort-of "digital SCA" in concept. Well, whaddya know? Looks like there actually *is* a digital SCA now.........

Still, DRM on FM would be interesting. Since the sidebands have already been grabbed by Ibiquity, looks like the SCA channels may be where DRM might exist.

(I need to do a bit more research on this flavour of the system, obviously.)

On the other hand, if the "mobile ATSC" thing catches on we might be seeing a lot of digital-TV-audio radios available in the future. Kinda' like the current analogue 2-through-13 radios, only more....errhhh...digital. (What was that thing about "the more things change"...... ;o) I have an ATSC receiver component in my apartment, I have heard ATSC audio and to be perfectly honest, Ibiquity doesn't hold a candle to it.

Since this is primarily an AM/FM board, I said DRM is mostly medium wave(as opposed to FM). What I should have said was that up until recently, DRM has been limited to transmissions below 30Mhz but is now being considered for use on the standard FM band. IBOC has been in preparation for many years. In 1990, it was decided this country should have a digital radio system. At first, a European system was favored but in order to make it work properly, use of the L-Band was necessary. Unfortunately, it was tied down by the government, which wasn't willing to give it up(something about national defense-there's just no pleasing some people). They offered instead, the S-Band. The problem was, it would require too many repeaters to make the system work at those frequencies. It was later assigned to what we now call satellite radio. With no other frequencies offered, several companies went to work on finding an alternative that would work on existing spectrum. They looked for a solution on channel(IBOC), adjacent channel(IBAC) and on a different frequency altogether. Each company came up with breakthrough ideas for their system! As time went on, the various companies merged until only one was left and they named it Ibiquity. They took the best, compatible parts of all the systems and created what we have today. DRM was not designed to work in a hybrid manner along with analog AM and FM. From everything I've heard, there isn't much quality difference between DRM and Ibiquity in the pure digital mode. FMeXtra is basically a better use of SCA frequencies. From what I understand, if there's multipath interference on the main station, FMeXtra won't help, other than to provide extended stereo(and additional channels). I don't think hearing extended stereo in a noisy environment is something I want. It also sounds very much like what killed FMX: The idea was to extend stereo coverage to the mono limit but if there was any multipath interference, it was actually increased!

"At first, a European system was favored but in order to make it work properly, use of the L-Band was necessary."

EU147 DAB, right??


Yes, not only is FMX a better use of SCA frequencies but (as I believe you may know) a tremendous improvement in terms of fidelity overall. (If only the system had been around when Muzak was still SCAing as its main delivery format.......)

What strikes me as odd is that most of the FMX stations currently operating appear to be in Europe. I am not certain if this is really the case or if it is merely the work of an ignorant Wikipedian but at any rate see~ http://en.wikipedia.org/wiki/FMeXtra (scroll down a bit, it's under the subheader "Stations Broadcasting in FMeXtra.") Seems the majority of them are in the Netherlands.......

I hope you meant to say "FMeXtra". FMX was a system to improve stereo coverage out to the monaural signal. It worked extremely well as long as there wasn't any multipath interference at which point, it increased the multipath. Yes, Eureka 147.

that seems right but I remember watching a video from 1995 about Eureka 147 DAB and in the video it clearly says that the system can be used in any VHF/UHF band not only the L-band I think in the UK it is used around 220 MHz. Some of the FMeXtra stations are in the United States mainly Minnesota and Tennessee I assume they are running this under experimental authorization.

I believe they ran into the same problem: No additional spectrum within the band.

no surprise but it would not work here 222 MHz is an amateur radio band albeit one that is not used frequently because of the lack of transceivers same thing with 902 MHz I don't want to see any of those bands lost. That seems to be the reason why IBOC DAB was what the FCC chose for terrestrial digital broadcasting in the United States.

"Converting a radio to receive AM stereo."

Like, who cares?

Here is the most current band-plan for EU147 that I could find~

Band III - 174-240 MHz (VHF)
L-Band - 1,452-1,492 MHz (SHF)

It is split up into several "modes"~
Mode 1: Band III, Earth-based
Mode 2: L-band, Earth and satellite-based
Mode 3: Everything below 3 GHz, Earth and satellite based
Mode 4: L-band, earth and satellite-based.

The Canadian implementation of L-band EU147 uses 23 channels~
1452.816 MHz
1454.560
1456.304
1458.048
1459.792
1461.536
1463.280
1465.024
1466.768
1468.512
1470.256
1472.000
1473.744
1475.488
1477.232
1478.976
1480.720
1482.464
1484.208
1485.952
1487.696
1489.440 and
1491.184

<http://en.wikipedia.org/wiki/digital_audio_broadcasting#bands_and_modes>
<http://en.wikipedia.org/wiki/digital_audio_broadcasting#_note-20>

Canada isn't allowed to use any of the satellite-based modes on L-band, because of possible interference to US-based military systems that use the same band, so they are limited only to terrestrial operation.

(It also appears the UK implementation uses MPEG2 Musicam for its codec. This, in fact, is the same thing I record the audio files on my CDs in, but with an MP3 extension for compatibility because my CD players don't recognise MP2 as a valid extension...)

<http://www.bbc.co.uk/rd/pubs/papers/paper_21/paper_21.shtml>
<http://www.bbc.co.uk/rd/projects/dab/index.shtml>

Really, though, for amateur radio 174-224 is rarely used. There is basically bandwidth sitting there doing for the most part nothing, which could be used for a US-based implementation of DAB. Likewise, post-February 2009, there will likely be a lot more spectra opening up which once was the territory of analogue UHF television. The EU174 DAB system supposedly works pretty much anywhere above 30 MHZ (UHF television, of course, operates *way* above that point) so if the Ham Radio band is an issue I don't see why the vacated TV channels couldn't be used instead.

(FCC people, are you reading/understanding any of this??)

If anything it would be a *very* good reason to stop trashing VHF FM and mediumwave bands with IBAC noise!!

Motozak2 said: Really, though, for amateur radio 174-224 is rarely used.

Yes, amateur radio ops don't use the 220MHz band much, but KGW, KOPB and KPTV like to use the 174-210 spectrum for their TV signals in the Portland area right now!

that is correct 174-210 MHz is TV channels 8-12 but the question is will these three stations use their current analog allocations when the digital transition is complete? Many others will be using their existing ones and some will even be in the VHF low band which has some interesting propagation characteristics that don't exist on high VHF and UHF. As for the 220 MHz amateur radio band when it is used that is mainly for links and packet but there are some FM voice repeaters and also FM simplex and also there are some VOIP nodes for both Echolink and IRLP in the 1.25 meter or 220 MHz band.

The problem is with low VHF(channels 2-6). KGW, KOPB and KPTV will return to channels 8, 10 and 12. KOIN will stay on 40, KATU 43 and KPXG will return to 22. The other interesting thing is that when KPTV moves back to 12, KPDX will move to 30, which is KPTV's current digital channel, instead of 48 or 49. KNMT will stay on 45. At this point, it's pretty much written in stone!

Semoochie--

When will all the digital channels start moving around as you mention? (Need to know so I have some idea as to when I should start shuffling the channel presets in my ATSC receiver all around.)

Late 2008 or early 2009, perhaps?

How come low VHF will be vacated? Expansion of the FM band?

(If that is the case and also happens elsewhere, there's some territory that Ibiquity, Eureka 147, whichever could dominate......)

Qpatrick--

I have heard some activity around 220 in the past. Seems a few years ago Evergreen School District used a coupla frequencies around 221-222 or somewhere for school bus radios.

Every so often I hear someone using a repeater on there, that seems to be DTMF'd to some other repeater up in Canada. (Can't remember which frequency it was on.)

And then they started using those odd cell phones with walkie-talkie functionality.................

The move to all digital TV is to be completed no later than February 17, 2009. I understand that low VHF isn't very compatible with digital television. Even so, quite a few stations will remain, even on channel 6. Hopefully, all can be coaxed away.

KPXG's ATSC feed on channel 5 seems to come in unusually clear at my place in east Vancouver. Even at home (not too far from the KVAN towers, in a valley) I can get about a 95%-97% copy on my EZ27 on an indoor, amplified antenna.

But also, that's in the summer when the weather is pristine (and NTSC channels 2/6 actually come in crystal-clear as well for at least a couple of months.) It should be rather interesting to see how well it performs in the late fall and into the winter when the weather is delta sierra.............!!

not bad but is the RF channel for KPXG-DT 4? I remember that used to be KWBP-LP but that was their call before the change from WB to CW their translator was moved to 5 so that KPXG could use ch 4 for their DTV station. There are many DTV and HDTV stations on the VHF low band there are about 12 on ch 2 alone and a few more pending. As for HDTV on ch 6 there are 6 stations so FM as secondary on 87.9 would work in most areas.

As I said before, KPXG will return to channel 22. All the local stations will abandon low VHF.

If broadband over powerline Internet is deployed, there will very likely be interference to the low VHF channels, as BPL uses frequencies up to 80 MHz. Another interference source, at least on the East coast, to the low VHF channels is sporadic E-skip, which occurs primarily in spring and early summer. I do not know whether these two factors played any part in the decision to abandon low VHF or whether there were some big bidders who wanted the spectrum. Does anyone know the answer to this?

"not bad but is the RF channel for KPXG-DT 4?"

Yes it is. My hands were cold when I typed my post citing it as somehow being on 5.........

However, in less than a year and a half from now this won't apply!! (That is contingent on if the FCC doesn't push the analogue-extinction date even further into the future as they have done before--twice, I believe......)

abandon low VHF? Not going to happen I found a PDF file on the FCC website that says the core channels after the DTV transition are going to be 2-59 we will be loosing channels 60-69 though. There are some bidders for the 700 MHz spectrum which will be re-allocated after the transition is complete.

> [T]he core channels after the DTV transition
> are going to be 2-59.

I find this interesting for two reasons:

1) The plans have changed a lot over the years. First, VHF was supposed to go away altogether. Then, low-VHF was supposed to go away. Now, they're only chipping away ten channels at the top of the UHF band.

2) From what I had previously heard, Qualcomm was seeking a nationwide license for UHF channel 55 to broadcast its MediaFLO (Forward Link Only) service. Verizon put such a transmitter on the air in Portland on January 5 of this year, broadcasting with an ERP of 50kW (see http://www.dailywireless.org/2007/01/07/verizon-launching-mediaflo/ ) The fact that this assignment is within the planned post 2009 UHF band suggests to me that this channel will be shared with free over-the-air broadcast stations.

Question: will TVs manufactured after 2009 not be required to tune channels 60-69 or will channels 60-69 be shared between television broadcast stations and other users?

Comment: this has nothing to do with AM Stereo and belongs in another thread.

I will try to get this back on topic for some people it is a moot point to convert receivers to AM stereo because for some such as myself sadly there aren't any AM stereo stations receivable in their area locally KLOG 1490 is wide band mono now, KGHO 920 has switched to talk and is no longer stereo, KYCW 1090 is now talk and stereo is gone there too, KKSN 1520 is now Spanish and no longer stereo, and lastly KDZR 1640 has obviously switched to IBOC recently. Now there is not a single AM stereo station that can be received in southwest Washington. By the time the signal from KBPS 1450 gets here it is already totaly destroyed by interference. This is only during the daytime hours at night the signal from CKMX 1060 still gets here but is only strong enough to overcome the IBOC sidebands from KNX 1070 starting about 2 hours after sunset and to about an hour after sunrise.

"All the LOCAL stations will abandon low VHF." I was thinking the core was to be channels 2-51.

"By the time the signal from KBPS 1450 gets here it is already totaly destroyed by interference."

It comes in very well in stereo in my truck. But then again I am in Vancouver, fairly close to the location of the transmitter. (KD7, Didn't you mention a while back, something to the effect that you live in the Olympia area?)

I have been able to pull in CKMX satisfactorily in stereo in the past (Mom's truck, on the same radio I later had in my truck) but haven't really listened to it in a while.......last time I really listened, they were still soft-rock/adult contemporary.

I will have to try and listen tonight on my way home from work......I have been working Graveyards lately (on at 1600, off at 0200, yawn) so that is right about the time that CKMX would come in well around here. I will try to write up what I discover tomorrow.............

KBPS is at Benson High School, just south of Lloyd Center. I suppose Vancouver could be considered "fairly close" to there compared to Olympia. I'd say it's pretty much light fringe from there however.

I am in Toledo about 40 miles or so south of Olympia.

Well, on the way to the restaurant tonight (where I am typing this--I am on my dinner hour right now) I copied CKMX in stereo on my Kenwood, down here in Troutdale. In the right channel was a constant, noticeable static "hissing" sound--possibly my stereo detector may have been picking up some odd IBAC channel or something else. (Not certain, tuning 1070 revealed a jumble of stations and heterodyne noise.)

I will listen again in about 4 1/2 hours on my way home!

Semoochie--
"I suppose Vancouver could be considered "fairly close" to there compared to Olympia."

That is what I meant, yes. Although Toledo is "fairly closer" to KBPS than Olympia as well! ;o)

(It's about half-way between Olympia and the Coove-- http://upload.wikimedia.org/wikipedia/commons/e/e3/WAMap-doton-Toledo.png)

I haven't listened to KBPS, but I might listen to it as well. I work in Troutdale, so I do have a bit of a drive = time to play with the radio and possibly kill myself from the accident I cause in the process. *snort*

I've picked up KBPS-AM in full stereo as far away as the city of Sandy during the day.

that and also being able to receive CKMX 1060 here disproves one misconception about AM stereo which is it cuts the coverage I say that is false and there is something I have done to disprove this too a few of my trans Pacific AM DX loggings are JOQR 1134 Tokyo JOHR 1287 Sapporo and JOLF 1242 Tokyo. These three AM stations have something in common they all broadcast in C-QUAM AM stereo and are all about 4,000 miles away!

I believe C-Quam decreases the groundwave coverage of a station, not just the stereo coverage but the entire coverage compared to not using the system. It isn't dramatic however and improvements may have been made.

when willl 62 turn on AMstereo again? and resumelive DJ's and oldies?

About 2:30 this morning CKMX was blasting in my truck almost like it was a local station. I was able to listen to it the whole way home.

It did drop out a bit going along Marine Drive, heading west past Blue Lake (driving by all the warehouses.) When I stopped at the flashing red light at the road between Qwest and Honda, it ended up being clobbered by noise. (Knocked out the ending of Johnny Cash's "Ring of Fire" and about half of Allison Moyet's "Should I Feel That It's Over".) But once I was on I-5 it came in almost perfectly, save for what sounded like a few lightning bursts.

When I got back to my place I tuned it on my Grundig (about 3:00 or so) and I could barely receive it. (I guess my truck radio must be more sensitive than the Grundig.....)

Anybody per chance know how many watts CKMX puts out at night?

50Kw:

http://www.fcc.gov/fcc-bin/amq?list=0&facid=99986

"When I stopped at the flashing red light at the road between Qwest and Honda".

Is this new in the last week? There hasn't been a flashing red light along Marine Drive anywhere. A flashing yellow at 122nd is the only light on Marine Drive from Troutdale to I-5.

"I am in Toledo about 40 miles or so south of Olympia."
"It's about half-way between Olympia and the Coove--"
Actually, Toledo is closer to Olympia than to Vancouver. 46 miles to Olympia, 63 to Vancouver. 72 miles to KBPS.

that sounds about right rather surprising too Toledo is a small town the population is less than 1,000 about 680 actually.

The traffic light at the corner of Airport Way and whatever road leads up to Marine Drive, between Honda (actually, it's "Tonkin" now; I'm a bit out of date) and Qwest apparently was down earlier that night and at the time I arrived there, it hadn't been reset. Hence, it was merely a "flashing red light."

I have never really paid attention to what street it is specifically, as I have tendency to travel mostly by following landmarks. (Does take lots of memory, but that's why my mind's virtual memory uses an automatically-managed, dynamic swapfile ;o)

And it wasn't the intermittant buzzing noise like what is put out sometimes by LED-based traffic lights; this was a loud, scratchy static noise. Kind of sounded like an IBAC channel but more than likely wasn't, as it seemed to cover about 980-1100 kHz (pretty wideband) and seemed to go away rapidly as I headed about two blocks west on Airport Way. Wild guess, but it may have been something at Qwest generating all the noise. Think Ernestine might have found her new calling? *laughs*

I haven't been through there since Wednesday, as I have been on va-kay since then. Maybe I will try to drive through there again sometime during the week, really, really late at night and see if the noise is still there..........