Guys, I caught a typo I made in post #44 regarding the tuning circuit.
Referring to 
you can see how the tuning coil is hooked up, I stated by error, that the output transistor has a direct connection to the antenna output terminal, when in fact, it has to pass through the tuning capacitor first. Then on leg number two, both the output wire and coil wire are connected.
I can not edit my typo in my last post, so consider this my correction.
Bruce.
Bruce, you got me thinking...I wonder how difficult it would be to add the correct C-QUAM circuitry to the SSTRAN AMT-5000? You can adjust the full 100 Milliwatts to the final! Add a coil-loaded antenna...or? Somehow this seems too easy. I'm missing something...
Doug
For those of you following this topic, here is an actual schematic diagram of the Chris Cuff transistorized AM C-Quam Stereo Transmitter:
Bruce.
BOARDMAKER Said:
The input cap is the cap on the previous op stage,the base bias is straight forward, diode in4007 or similar, and the op stage is a series blocking cap, say 1nf, then the usual series loading inductance, and a small trimmer capacitor to ground, as in the amt5000 op stage
The 10 ohm resistor from emitter to ground could be decoupled with a 1nf cap to increase gain, if it needs it.
Just noticed a fatal flaw, the bias line to the base of the transistor needs a series rf choke to pass the bias but to block rf!
MrBruce Said:
Boardmaker is that diagram for the Chriss Cuff or the AMT5000? Your diagram does not quite match the schematic of the Chris Cuff transmitter output stage in image 6.
Bruce.
Hello Guys!
Bruce,
This is just my suggested final to try, instead of the version of image 6.
I test my various part 15 transmitters in to a simulated 3 metre antenna load.
This simulated load consists of a series capacitor of 33pf and a 50ohm resistive (dummy) load.
I also have a Racal Dana absorption meter that has a built in 50 ohm load, and -23db attenuated sample out, it accurately reads 100mw, so is very handy to use with a series capacitor on the input, to use as a simulated 3 metre load.
When tuning the amt5000 in to it, max rf out does peak with the extra turn on the amt's variable capacitor, when comparing the current peak of the amt's final stage.
This is thus showing the class e efficiency peak.
I also have a practically new frequency agile Rangemaster on the way, so i will compare the output of that to the amt5000.
Paul.
Also guys and gals, I am interested in getting a 50 ohm impedance out of the Chris Cuff transmitter one way or another, so I can test that amplifier, which requires a 50 ohm impedance.
If anything, I need to know without using special equipment, that I have a transformer that is changing (lets say for the sake of arguement, that I use a 2N3035 transistor, then feed the output into a transformer, then into the amplifier) I need a transformer that takes that Transistors output and converts it to 50 Ohms.
I have a few binocular type cores, to which I can wind a primary and secondary coil on, however, I need to know the exact specks on the 2N3035 transistor http://download.njsemi.com/2N3033%20-%202N3035.pdf and what is required for a transfomer to match to the 50 ohm impedance.
All my test results will be done using a 50 ohm dummy load and I will post back the results of each test.
Right now, I can tell you, the transmitter is not at all driving the amplifier, test range at last test with the high powered transisitor removed was 20 feet, I plan on putting the 2N3035 back in circuit, but I need to feed it into a transfomer with an output impedance of 50 Ohms, this is very important that I get that 50 Ohms, to continue testing.
Bruce.
Okay Paul BOARDMAKER I read your last post.
But I need to ask you about this picture, is the RFC an RF Choke or an RF Coil? Also it looks like a seccond coil and a capacitor just before the tuning capacitor and antenna, what value is the capacitor and what type of component is the last coil?
Yes the supply to collector coil is a rf choke, i would guess 330uh would be ok.
If you are going to use this output to a 50 ohm load, then the series output capacitor needs to be 33pf, and the series output inductor coil needs to be variable, approx 330-700uh, as is typically used on part 15 output stages.
Paul.
Okay is anyone else following this topic able to also try these mods?
I have my Chris Cuff transmitter on my work bench, I just un-wound the coil mine came with. It has a total of 100 raps of coated speaker coil wire wrapped around a plastic cigar tube, just so everyone knows this.
I will keep everyone updated as usual with any progress I make, stay tuned.
Paul I am going to draw out the circuit on paper and make an attempt to use it.
Bruce.
Could you please take your diagram and add in all the component values, including the transistor type and part number, also the varible tuning capacitor tuning range? There are several unidentified parts in your diagram, I would like to try to building this circuit.
Bruce.
First, thanks MR Bruce for adding a link to the schematics page again, I didn't know where it had gone to, site's sometimes goofy. .
I just have some documentation today, stuff I've been reading. The first thing to look for is Motorola's AM stereo introduction for CQUAM. It used to be on line, but I can't find it now, except for some Facebook pages that have it in their files. If you're on there, you might be able to get it if you log in, I couldn't click any of the links.
"MOTOROLA AM STEREO INTRODUCTION.pdf"
That's the search phrase that pays. If you can find it, it's well worth it since it's a breakdown on the AM stereo system from Motorola's mouth. I have to think that this document is what some radiomen have used to work up CQUAM exciters, from Alfredo on up, so it's well worth a look.
Here are some other useful links for those looking to understand more, and perhaps to soothe your quest for knowledge if you can't find the introduction manual above. I archive and save everything that's useful, and have for years. You'd be surprised at how many documents just don't seem to be available after time has passed, while at the same time newer documents have come on line.
The IC used in some receivers, like Mr. Bruce's TM-152, MC13020 data sheet. (The current generation chip would be MC13028 with added refinements)
http://www.e-ele.net/DataSheet/MC13020.pdf
The Motorola Model 1300 AM stereo exciter has met the Federal Communications Commission .... .... INTRODUCTION TO C-OUAM _' ...
http://meduci.com/Motorola_1300_1310_Exciter_And_Modulation_Monitor_Manual.pdf
Older Aussie CQUAM stereo description and build it yourself AM stereo decoder. Uses MC13020 decoder chip.
http://messui.the-chronicles.org/sch/kits/AMstereoEA.pdf
Blogpost: "C-QUAM is a method of broadcasting an AM signal in stereo developed by Motorola. Advocates of the technology say that it is superior to AM HD radio."
http://www.radiosurvivor.com/2013/12/10/want-to-revitalize-am-radio-start-with-better-receivers/
Thanks for all the links Nate Crime
Here is where things stand right now.
In the post where the schematics are posted, I noticed a slight error in schematic #6, it involves the circuit numbers trace, that help pick up and continue a circuit on the next page.
It is not a big deal and I had Jeff correct the error and he sent me page 6 with the correction, however, I can not upload the corrected image and replace the original one, because my post edit time limit has long since passed.
Those of you who have the page:
will notice to the left side of the image is a 47pf cap also labled marked 471, this is the continuation of trace E from page 5!!!!! (It is labled RF INPUT FROM ENEVOLPE MODULATOR FROM PAGE 5)
The letter E was mistakenly placed in the diagram, where you see the first antenna symble, next to the 0.047 capacitor, that should be the letter G, NOT the letter E!
Now if you follow the trace down to the 150uf capacitor under RF POWER AMP STAGE, you see another letter E, that should be the letter G, NOT the letter E!
Please make those corrections, so you know that trace E from page 5 near the 1K vari pot marked 102 does not intercept with that 0.047uf near the letter E in the old schematic, it intercepts with the 47pf capacitor ONLY which is just before the first 2N3904 transistor, below trace F on schematic #6.
Bruce.
Here are some quotes from the MOTOROLA AM STEREO INTRODUCTION.pdf
"Compatible quadrature
The Motorola AM stereo system is not complicated at all. It simply takes a pure quadrature signal as just described, and extracts the phase modulation components of the quadrature signal and phase modulates the broadcast transmitter. At the same time it sends L + R audio to the audio input of the transmitter as usual. That's it! The advantage is that a very nice AM signal is always transmitted so that the envelope detectors are compatible, but that the phase modulation of the carrier is derived from a pure quadrature modulation. The result is a signal with most of the advantages of quadrature modulation while maintaining all important monaural compatibility."
I thought this was an important description in light of how some of our stereo generators produce their carrier frequencies:
"Note that pure quadrature is generated by taking L + R and L - R and modulating two balanced modulators fed with R.F. signals out of phase by 90 degrees. In this case the 90 degrees phase shift is derived by using a Johnson counter which provides an input frequency (four times the station frequency) by four and automatically provides the digital signals precisely 90 degrees out of phase for the balanced modulators. "
Thanks for the updated info on the schematic Mr. Bruce. Good circuit BOARDMAKER, it looks like a class B amplifier. That should have a little more power than the class AB or A that I might have suggested as a quick amp.
My Cyprus c-quam exciter is a direct copy of the c cuff exciter, with the addition of a bd135 linear o/p stage, and uses a binocular ferrite to give a 50 ohm output.
I don't know how many turns are on the primary and secondary, so hence i suggested the circuit before.
Regarding c-quam modulation, to me it is not pure quadrature, but a dynamic skewed adaption of it, due to the combined phase angle dynamically varying with L-R and L+R ratios ?
To me pure quadrature modulation would not have the addition of the 0 degrees L+R modulator that dynamically skews the phase when mixed, to make it more envelope friendly, that is how i see it.
Paul.