Interesting calculator for Part 15.209 on a certification website.

ACB - American Certification Body

Barry of BBR Yardwide

I have a topic going on concerning the Chris Cuff AM C-Quam Stereo Transmitter.

I have asked Chris Cuff for permission to share these with the group here, so everyone has an idea of how this transmitter is designed. Permission was granted for me to share these here at part15.us by Chris Cuff.

Below are schematic diagrams that cover the whole kit design.

Although the images in this post are not clear, below are the links to each image, click those to see a decent copy with magifying capabilities for a better clearer view of each schematic diagram.

Bruce.

Here's some interesting info about getting the most coverage in low power to BETS-1 and part15 FM transmitters

http://www.engineeringradio.us/blog/2011/08/fm-stereo-vs-station-coverage/

This is why Decade MS-100 comes in mono and stereo versions, and why it's selectable on the stereo one. Ramsey's and the wholehouse 3 also are selectable.

Mark

I have just completed the back to back test of a total of TEN brand new C. Crane FM Transmitter 2 units.  My goal was to test for consistency in field strength across a sampling of the same devices. 

I also did some other interesting tests with one unit while I had everything setup.  Available for your study as a pdf at:

http://www.ironrangecountry.com/ccranetest2.pdf

Also if anyone might be interested in a very slightly used C. Crane transmitter let e know ;)

TIB

I did a rather extensive round of tests on this transmitter, which I stumbled upon for sale on ebay. 

Please note this is in NO WAY connected to the Hamilton Rangemaster folks.  But thats how I stumbled upon this transmitter. 

This transmitter claims to be FCC Part 15 certified, but that's clearly not possible as my report will show. This is an excellent example of how a complete neophyte to Part 15 broadcasting can get sucked into buying a very illegal transmitter.  Pour a cup of coffee and have a look:

http://www.ironrangecountry.com/failsafetransmitter.pdf

TIB

So, I've been hanging around with a bunch of record player nuts (I only have about 50 myself) and one of the guys just posted video of his just restored, Philco RP-1 from 1939 that has the famous Philco Phono Oscillator built in, so you could play records through your radio.  VERY cool.  I do wonder what the range might be LOL.  Have a look:

https://www.youtube.com/watch?v=JJZzZIixQvw&feature=youtu.be

TIB

Just back from the field after testing 5 Whole House 3.0 tranmitters for field strength.

Exact same setup as for all my other field strength tests.  Exactly.

I don't feel like typing up a big fancy pdf for this one, LOL. 

I tested 5 Whole House 3.0 transmitters, all within a minute or two of each other, under identical conditions.  Of the 5, field strength at 3 meters ranged from a low of 5635 uV/m to a high of 7585 uV/m.  Remember, legal is 250 uV/m.

So, one guy would have received much better coverage than the other 4 guys.  And they're ALL illegal. Compare to the C. Crane I tested a week or so ago. All under the limit -- I believe the high score among those was 110 uV/m under identical conditions. 

This is a big part of the Part 15 FM problem.  None of the different transmitter brands are even close to being "on the money". And since the WH 3.0 is certified, people buy it and use it's coverage as a standard for a legal device. Counting last year I've now tested 6 of these all under the same conditions and all were illegal. 

I did not test these with the secret "Canadian" setting, nor did I test them with the illegal but still included in the US version, alternative long wire antenna. 

This is why you can watch videos on Youtube of guys demonstrating their Christmas light displays using the WH 3.0 with great results, then driving away in their cars to show off their coverage. They're several multiples over legal. 

TIB

I've just ordered the current model Broadcastvision FM transmitter for testing. If it arrives in a timely fashion I should have field strength tests in a week or so.  Our forcast (so far anyway) is calling for sunshine and 60 degrees at the end of this week (which is very uncommon up here this time of year). 

So if it arrives in the time stated, and the weather holds I should be able to pull it off.  This will likely be the last possible "out in the field" test I'll be able to pull off this year. 

And if anyone cares, I have three Whole House 3.0 transmitters for sale, brand new except for about two minutes of operation for testing. They're on ebay with a buy it now of 89.77 including free priority mail shipping. That's about $40 or so below buying one new from them after accounting for shipping.  Just in case someone wants to take a chance on one!

TIB

I have an LPB RC-6A carrier current 

transmitter that I just took out of

the box from our move a year ago.  

I just started running it into a dummy

load about 5 minutes ago.  I have crystals

for 860 and 1020 kHz.  These are not great

channels, although 1020 is very quiet during

the day.  I really want to be down in the 

bottom of the AM BCB somewhere.

Anyway, I'm getting a good carrier.  I have not

tried audio yet.  The transmitter has some odd

problems - but it should operate.  It is a vacuum

tube model from 1971.  It uses 3 6AL11 compactrons

and is built like a tank.

I also made a very simple line coupler.  It isn't the

greatest thing in the world, but it is safe and does

work after a fashion.  Oh - and the transmitter runs

about 6 watts out.  Many of you will remember that

I did experiments with this unit in the past.  

So, we'll see what happens.

Best wishes to all.

Brooce, Part 15, Hartford, CT 

Yesterday turned out to be a beautiful day to be in a field, field testing! Mid 60's and sunshine!

Here then, I present my tests and review of the Broadcastvision FM Transmitter in handy pdf form:

http://www.ironrangecountry.com/broadcastvisiontest.pdf

TIB

I just wanted to send up a flag saying

that this project (as named above) is

starting to happen.  

It's a big fat coil which will load up a 

Part 15 AM "3 meter" stick.

I have built several in the past.  I built one

many years ago for a Ramsey AM-1 transmitter

which had been modified for crystal control.  

With this coil and some radials and a 3 meter

stick, I was able to get the AM-1 to transmit

to around 1/2 mile or so.  

I made another one for my SS-Tran AMT-3000

years later.  The furthest that transmitter "went"

was 2 miles.  The SS-Tran was modified, somewhat,

though.

This coil is made out of junk, really.  It is just

another experiment that is going on here.   

It is not a polished project like some of the

great work I have seen here on the board

fairly recently.

It's just a test coil, using a variometer and

a movable ferrite rod, with lots of coil taps.

Anyway, I'll be reporting on this.

A parallel project is a magnetic receiving loop

for HF.  These kinds of things are fun and don't

cost much.

Oh yeah, if you are not familiar with variometers -

Google is where you want to go.  There is not much

to a variometer and it is fun.

Best Wishes,

Brooce, Part 15, Hartford, CT  

The author of this video shows how he built a three component AM transmitter and then how he added some more stuff so he could enjoy "decent music" in his antique truck using the truck's radio.

https://www.youtube.com/watch?v=YNGs-IX_B2s

Hi guys!

Doug here. I just got my new SpitFire AM Transmitter in the mail from the UK. It's on the air on 1500. I have the wire antenna taped to a piece of wood trim. It's leaning against the wall. With NO earth ground, and the internal ATU turned OFF, my whole four-plex, plus my neighbors around me receive a loud, clear signal! And NO HUM!! That's a first!

I tested it using my laptop. I need to find a spare mixer to feed it from my Orban 424A Comp/Limiter. So far, I love this little thing!

Doug

1500 am KLW

I have a ProCaster that I haven't used in a while.  I'm thinking of selling it, so I pulled it out and hooked it up.  It's not a great installation, with a minimal ground, but without enabling the built-in audio processor, it sounds very good.

The problem is when I enable the audio processing.  The sound gets a high pitched whine in the background, and it sounds hollow and seems to be coming from a great distance.  The compression and modulation pots still work, and seem to do something, but overall the sound is very crappy.

I'm wondering if anyone who is familiar with these transmitters has any ideas.  ChezRadio has a fixed price repair service (US$65 + US$35 or shipping) but I'm trying to avoid that if I can - in Canadian dollars add another 35-40% for the exchange rate.

I'm currently using software audio processing (SoundSolution with Zara 1.4.4) but the load (with streaming software) on the old laptop it's running on is causing problems.  Besides, I suspect that the built-in processing on the transmitter will sound better than SoundSolution, particularly with the120%+ positive peaks it supports.

I should mention that this is one of the first ProCasters built - the tuning meter inside is marked Talking Sign (they used up the remainder of the Talking Sign parts in the first builds of the transmitter.

Hi guys!

I don't think I've ever seen this discussed before. What would music sound like on a CB Channel? Could it be AM quality or better? You'd bave to lock the mic in "key" mode. Or something like that. The comp/limiter hooked up to the "mic in", and levels set.

I don't recommend doing that. But I sure would be curious to see what is possible. I see music is played on the HAM bands from time to time. But I am not a HAM. Can music be played on the LW band? 

The reason I mentioned CB is, everyone seems to have one. There are so many damn channels, I'm surprised no one has...well. I don't condone anything naughty. Just curious, that's all. Ever heard music on CB?

Doug

Hi everyone!

Finally got my Rigol DSA815-TG. Let me just add that I was broke before I purchased it and even "broker" afterwards. Was going to get a Rigol DSA705, but decided I was better off to buy the 815 because it would be cheaper to buy that unit instead of later purchasing a separate tracking generator, etc...

So, I did the proverbial 250uV at 3m with a 1m antenna test. I saw something regarding a half wave dipole being used however went with the 1m because I seem to recall that being the one required. My equipment under test (EUT) was a C. Crane FM2 I purchased two years ago. At first, I was going to test the EUT by taking the spectrum analyzer to the transmitter. Then I realized it would be easier to take the EUT to the test equipment.

I had to move things around to have a place for the antenna that was 9' 10" away from where I was adjusting the FM2. Set up was:

Antenna -> cable -> 75 ohm to 50 ohm pad -> cable -> spectrum analyzer

I calculated an antenna factor for the dipole of 7.486 at 93.5 FM. To this I added the loss for the cables, etcetra for a total of 14.494. My goal was to adjust the pot in the EUT to 33 dbuV so that I could have a total measurement of 48 dbuV; AF+Loss+Reading.

Something I didn't realize until right before I got the SA is there is a difference between dbuV/m and uV/m. Fortunately I found the formula uv/m=10 to the power of (dbuv/m divided by 20). The lab that originally tested the FM2 for compliance used 48 dbuV as their limit. I did the same.

I've got other transmitter I'd like to bring to compliance. Been thinking of contacting the FCC to see what they would think about me taking on such a project.

...with the same antenna as my Rigol 815 spectrum analyzer is a good 20dbuV or more off. Surprise, surprise! All readings were on the low side. One of the main reasons I got the 815 was to see how accurate the sub3G explorer was.

Funny/dumb story? When I first got the Explorer, I used it to measure the output of a Ramsey radio with variable power. I started out low, went up. I kept getting a reading much lower than 250 dbuVs (I thought dbuV=uV). I then turned the power up all the way. Still, way below 250. Finally, I put the Explorer right next to the antenna; Reading was only 60 dbuVs. I thought, wow, I can really ramp up my power.

Twas a learning experience. Trying to figure out what to do with the Explorer now.

Speaking from where I live as a few forum members are from Canada, among other places.

A simple set up indoors with an AM transmitter with the wire and maybe a ground through the a/c cord won't get you as far as FM will. Probably the majority of people don't have the access or facilities to do the not so easy outdoor install with ground radials etc to get the extra range. As for another member getting such good results with the Spitfire in a building of all places with just the indoor install with no ground is exceptional and maybe is blessed with no electrical noise to drown it out. But most all over North America AM is killed by the electrical buzzzzzzzz that plagues the AM band in all houses and buildings and in the house where I am it's across the whole band and at the signal strength of the local 50,000 watt stations.....wipes out everything! Am is only good if you go outside away from the hydro(ac power) like the street. As for if something was there that people want they will listen, My brother told me that he will never listen to AM no matter what is there.....listen to this he said! If I were to be on AM here where I am it would be for MY USE ONLY as no one would listen and here in Canada there's no AM transmitter approved for "broadcasting". If my goal is to have listeners then FM is the way to go here as BETS-1 gives us increased coverage than part 15 does and in mono a little more. Also the Decade MS-100 is approved for "broadcasting". So here, the statment that a medeocre AM is better then the best FM is not true. And if you don't have access to the ideal AM set up....not medeocre, FM gets you farther and doesn't have to fight through the noise to do it.

FM is also much easier as a good FM set up needs only an indoor place on a shelf and works with a indoor antenna thats 30" long and there's no ground involved. Much simpler for someone to do.

And then there's the nightime thing.....forget it....even the best outdoor set up with a compliant transmitter looses the range at night drowned out by the clutter of 5 stations coming in on top of you. FM doesn't....it works day and night.

I grew up with AM and in the 60s and 70s....and eighties for oldies and it was clean. but in the mid nineties all the noise started creeping in till you have what you have now and this is what kills AM. I can't listen to something that I want it's so bad here.

Here in Canada FM IS the practical choice if you want more than yourself listening.

Even in a rural area out in cottage country where I had listeners around me no one would have listened if it was AM.....most people had there radios in their garages or porches by their cottages and the noise was brutal even out there and no one would listen through that. They would have to be right beside me to get a clear signal.

AM to me is a last resort only if for some reason I couldn't do FM.

Mark

Greetings all,

It has been many moons since I posted, but I frequently check-in to see what the hub-bub is.

Anyhow, I have some questions and would like any input.

At one time I thought I wanted to create a community station, but since have decided I prefer house/ yardcasting to the various vintage radios I have (too many hobbies already.)

The transmitters I have to date are: Ramsey FM-10 (my primary transmitter), Ramsey AM-1 (which gives me fits and have all but given up on), a homebrew 1 MHz transmitter (my first transmitter :p), and a Tape-mitter.

I know the FM-10 is a splatter box, but up until now has worked for house/ yardcasting.  I am considering an AM transmitter to be able to receive on radios sans FM. 

Many will probably recommend the Talking House due to plugand playability, but I am concerned about audio quality: much of the content I transmit is Old Time Radio which can be sub-par audio to begin with (32kps -64 kps), and etc.

Others will recommend both the SSTRAN 3000 and 5000; perhaps some the Spitfire.  Not having heard the TH, SSTRAN 3000/ 5000, or Spitfire it is difficult to decide.

I will say I am happy with the sound of the FM-10, I just know that it a splatter box and may not be compliant with Part 15 - I do care about compliance.  I want to be able to utilize the AM radios I have with an AM transmitter.

Any help/ recommendations/ tweaks would be appreciated.

Chance

so i have a late model procaster with it's interface box.

we tired to hook it up at my friedns apartment.

i mounted Tx on balcony. grounded the ground to the faceplate screw on AC outlet.

i hooked up everything up minus the barix and tested the signal and it got out beautifuly covering everywhere i thought it would cover with a unmodulated carrier.

so i procedded to hook up barix to tx via the procaster interface box and plug it into xfinity cable modem.

the resulting audio was very low and distorted and there was a motorboating sound overtop my stream audio from barix.

as soon as i dosconnect coax cable from modem or barix from modem there is a breif time where the audio is loud and clear till the barix buffer empties.

plug it back into cable modem and audio is distorted and motorboating again.

i bring it down here to my apartment and hook everything up the same way and i can't replicate the issue here and i have the same exact service and modem he has.

any idea's, i did try a audio ground loop isolator with no luck.

i'm thinking the cable and ac are at different ground potential IE: not bonded together at service entrance per NEC but either cable service is ungrounded or on a seperate ground from electrical service grund.