God doesn't want me to run for political office, but He does want me to broadcast on 1710 kHz.

BUT 1710 KHZ ISN'T A PART 15 FREQUENCY!

Wrong. Just check 15.223 - Operation in the Band 1.705-10 MHz.

It's very simple: The field strength of any emission within the band 1.705-10.0 MHz shall not exceed 100 microvolts/meter at a distance of 30 meters, and so on.

The "and so on" part gets a little complicated, and at the end of the day the question is "How can I get my SSTran AMT3000 or AMT5000 to do it?

KDX Worldround Radio is doing the engineering with plans to be on 1710 kHz by Christmas.

More studies from me tonight as I've bookmarked the total list of field NOUO's. I can see more clearly why even asking for 1,000 uV/M @ 3 meters may get shot down the first second the petition is created. Maryland didn't even publish the field strength but lots of activity in NY around the Brooklyn and Bronx areas. All well below 1,000 uV/M at 3 meters. This message seems to ring in my head loud and clear that soon the only place to play Radio will be AM. I don't even think we can get 87.9 temporarily out of the gray areas. Field strengths in the 600's will get you busted I'm sure even 300-400 would as well. I'm sure it was not a Whole House FM Transmitter at the secret power level. At this rate more like a Belkin with a wire soldered to the PC board as an antenna or C. Crane with a lead wire clipped to the antenna without turning up the put. Some of the 700 and above may have been a certified transmitter like the Whole House FM Transmitter modified or at secret power. Question too is what about the Ramsey transmitters we know are just a little higher than 250 uV/m? I could not understand why folks were dead set against the PRO FM movement or initiative and now that I had a chance to calm down, Study, Look, Listen and meditate on what the information should be saying to me is that trying to get more field strength for every user in all cities of the USA will NEVER work. I'm sure only if we had 87.9 Mhz it may have been possible or petition the FCC to allow 1,000 uV/M on a city by city basis. How would anyone do this? I'm just thinking of soon giving up FM I'm sorry but it might not be a good idea and it really seems like it could be a waste no matter how bad we really want this and believe me I WANT THIS. But studies show me little chance with all the translators and more AM stations wanting to be on FM. I'm going to continue to see what the Talking House AM transmitter will do. So far my FM signals are not gaining me any extra listeners in my local area as no one locally contacted me by the Rockline and NO Elizabeth City NC IP's are showing up in the stats of Icecast V2. It tells me that the range I am getting on FM isn't enough to get people to hear me to try my Internet station which was my intent in the first place. And I'm not jacking up my FM power. If anything I'll lower the FM power to the -48dbm setting on the SainSonic AX-05B and use the 87.9 Mhz only as a link to the AM transmitter or better yet try and use my own Wifi trick to link it to a smartphone that is not active and plug it into the AM Transmitter and put the AM transmitter on the second floor as Station8 suggested. I'll still try with the petition if you guys want but as Tim says Music and just because we want to be heard won't work and now that I published the WiFi trick the FCC may simply tell us to try Wifi Radio or AM or Internet Radio instead. Again it hurts me to have to admit defeat here. I'm not one to give up easily. But if I thought I'd win i'd keep pushing ra ra ra but really I'd go down as an insane maniac who wants Power over the airwaves. I don't condone this jamming of other stations and wars either. If we increase the strength for FM without the forcing the manufacturers to have the scan before transmitting done we'll really mess up FM worse than it is already for many of the US citizens living in metro areas. That too is something I can't live with either. I had to fight myself as I write this. Its against every bone in my body to admit this fact but guys its true. Its not the fault of NAB, SBE, whatever whatever its a fact of science 101. More people means more stations, more inter mod, more possible RF interference. We'd have a better chance at forcing the manufacturers of receivers to start filtering the Radio's better and be more sensitive for AM and FM. This will help some. Even that stands a chance of getting shot down but its less insane that the making High Power part 15 FM for everyone. Secondary service well we learned about LP-10. Heck even LPFM is in jeopardy. Lets try and work with AM and come up with ways to improve it. Album Rockers will just have to deal with the laws that be and science. They want Stereo buy an AM stereo receiver. They could start donating to my station not just one company that has been giving $100-200 a pop for the equipment I use to run my station. That one company has done a lot just wish others would help and not complain when my Internet acts up and some skipping happens. I know Progressive Rock is picky but if they don't pay the bills I say they should not complain about Mono till I can figure out AM Stereo. Like I said if you want to push on we'll see where it goes but I'm getting Emails from people who don't want to lose what they have and really don't want to have me push so hard. So with that from what I've learned it just won't get us more power on FM. Now if I got it wrong tell me and we'll try a strategy. But how do you deal with these facts?

I had a horrible possible spur discovery last night just before bed. If it wasn't already a kick in the nuts to have to admit defeat with the FM initiative of more field strength due to the facts that presented itself during intense study and a reality check I found out that my SainSonic AX-05B may not be as nice as I thought it was. Imagine that why is that not a surprise when it rains it pours as they say. Well just before bed and I noticed a slight hum on my TV 3 feet away from the TX. At first I thought it was the mini refrigerator I have in my room for my cans of pop. I turned off the cable box and heard the hum. Shut down my Radio station and at last turned off my transmitter after a whole daytime show lasting till 4AM. Hey hum gone. Oh oh Huston, we have a problem. Danger Will Robinson, Danger! I turned the transmitter back on at the high power setting. Hum comes back. What a kick in the pants. I'm glad this was discovered now instead of a NOUO from the FCC. I remember telling you folks that at high power and at 10 feet it would bleed a boom box but go outside and its gone and everything is normal. Scratching my head and reading about the CZH-15A it all rang in my head too clear. This thing could be doing what the 15 watt CZH-15A done causing spurs on the lower frequencies below the FM band. I decided to switch to low power. Now I fired it up and NO HUM! Problem solved! Yes that is solved I can deal with that but No signal outside my house that is use able for reception not even on the porch. If I am outside and follow the contour of the house I get signal. And get this IT FOLLOWS THE POWER LINES!! What carrier current FM? What did SainSonic do? It has to be inches from the lines but if I walk under the power lines I hear my station till next door as long as I'm outside with the boom box. Does this transmitter feed RF into the lines either accidentally or on purpose I don't know. Is the signal use able inside people's houses? Don't know. I'll need to see when someone buys that empty house next door if they plug their FM Radio in and tune to 87.9 Mhz what will happen. Here I'm talking about carrier current FM and I already have a transmitter doing it and God knows what else. Damn the harmonics or lower spurs arent interfering at low power but imagine what damage this thing could have caused 10 feet away to the neighbor's house in front of me. Not a darn bit cool (I'm trying to keep it clean here as I slam my fist against the desk in anger at a mess I could have caused. I wish I had a spectrum analyzer just so I could see what this thing is up to. That transmitter should be tested by someone just for the sake of part 15ers like me who invest in transmitters when low on cash. I guess I should really had just bought a Talking House AM transmitter with that $54 but I'd always be wanting to test FM not knowing. Folks I know now. Save your hard earned money and if you want FM get something different. Even if you have to buy a scoche and if you have extra wire on it your on your own for you may be over the 250 uVm @ 3 meter rule. We will know if someone has a Patomac FIM 71 to test. I guess Carl can tell us did you get bleed from the Scoche you had keep forgetting the model number. And if my memory serves me right it traveled further than the low power of the SainSonic AX-05B and none of the damn spurs either.  Even the Maxell P-13 looked good in review but can only transmit on a few channels.  I'd want to modify it to have a digital display. What are your thoughts?

Here is a list, based on my experiences, of what I feel are the best sounding AM transmitters (my opinions of course).  The ones at the top of the list, while not sounding as good as FM mono, actually sound pretty decent (much better than I expected, as good or better, in fact, than most commercial AM stations).

1.  Hamilton Rangemaster - the priciest of the lot, but the best sounding, particularly with an Inovonics 222 and Symetrix 421 before it

2.  ChezRadio ProCaster - sounds almost as good as the Rangemaster with the built-in audio processing, at a bit lower price, and with easier installation and tune up

3.  Talking Sign - a few cuts below the first 2.  Sounds OK, inexpensive and uses a wire antenna so OK indoors (you can also add an external 50 ohm antenna).  Discontinued.

4.  Talking Sign - the earlier ones did not sound good at all.  The IAM ones sound better, but still a cut below the Talking Sign.

I don't have experience with the SSTran products, but from what I've read, they can compare with the best.

For myself, I have no problems recommending either the Rangemaster or ProCaster.  You can pick them up more reasonably priced used (anywhere between $200-400).  The ProCaster has the added advantage that you do not require any external audio processing (although you can do it at the computer end with the Rangemaster without extra equipment).  If you are concerned with sound quality, particularly after all the talk of the advantages of Part 15 FM, it would probably be better to spend the extra $ up front - it will save further down the line as you become dissatisfied with the results (unless you absolutely just don't have the financial wherewithall, of course).

As far as range goes, my experiences tally with the AM Transmitter Challenge conducted elsewhere (minus a few transmitters that I've never used).  The Rangemaster had the best range by far, followed by the ProCaster, with the Talking Sign and then the Talking House following up the rear.  You can increase the range of the Talking House with an external antenna or using the somewhat rare ATU.

All this jibber jabber about increasing the field strength and getting sucker punched when we find bad news in our studies the real question is Can anyone actually hear you inside of a building?  I know maybe a wood house or not?  I know my SainSonic AX-05B sounds Rock Solid on a car Radio sometimes up to 1/4 mile.  But as I've mentioned NO ONE locally called the Rockline and requested a song or even told me they could hear me.  I have not had the opportunity to take a Radio into someone elses house to find out Can it even be heard?  AM I know can be heard inside a building but the real question can I actually be heard inside a building?  What buildings could I be heard inside and is it even something possible at all to be heard even next door?  Supposedly someone can hear their transmitter inside a shed in the yard.  Supposedly if the appartment is next to you and I mean 10 foot or less you could be heard.  I know the signal will follow the mains to a certain extent.  But the question has pondered my mind and brought up elsewhere as well.  Just a little something fresh to think about.

As we are moving out, most of my really

good stuff has gone to my trusty Brother's House.

Such as the wonderful AMT-3000.

So what's left here?

In the junk pile there was a Ramsey AM-1 that

didn't work.

Before you laugh too hard, I will mention that

this transmitter was modified, and I was able

to get it to go 1/3 to 1/2 mile away from the house.

I don't remember the actual distance, but it was

pretty good for a transmitter of this kind.

A stock AM-1 will FM like crazy, or at least mine did.

Still, for yardcasting it was OK even with the FMing.

Later, I built an oscillator from the Medium Wave Alliance

website (remember them?) the crystal controlled kind.

I took the VFO LC out of the AM-1 and fed the crystal osc.

into that point. 

It worked.  Now there was no FMing anymore.

The transmitter required some EQ, and I did that.

I also built some huge loading coils on buckets from

the hardware store - I even made a variometer.

(This is a big coil that rotates inside an even bigger

coil - you rotate the smaller of the two - and you can

tune the thing - the coils are hooked together in series.)

Anyway - until I got the SS-Tran AMT-3000, the AM-1 was

tons of fun.

So just this night I found it in pieces in a pile.

The crystal osc. had been ripped off, a choke was

halfway off the board, some wires were broken -

there was no case, and no power indicator light.

(I had a nice yellow one.)

Anyway - I patched it together and put in 9 volts.

(It might really need 12 - I don't remember.)

I hooked up an IPOD which was playing "Hey There,"

by Sammy Davis Jr. (1954?) and it came though the

radio.  It sounded very good.  "Though she won't

throw a crumb to you... you think someday she'll

come to you........."

I ran about half the song through in the test, and I

was quite satisfied.  No transmitting antenna has been

put on yet.  (Another homemade tunable loading coil would be

required.)

So there's another Part 15 rig working.

I thought the crystal was on 1700 kHz, but

it turns out it is really on 1670.  I'm glad the

1670 rock survived the junk pile existance.

Crystals from 1590  and 1700 have been lost.  

Oh well.

There is a weak highway TIS station on 1670,

but if my signal doesn't leave the house, it

doesn't matter.

These crystals are very expensive, but I think there

are 1650 rocks on the net for very very little money.

1650 must be a common crystal needed for present

day technology.  (Am I right?)

It was really fun getting this old thing going.  

It was all I had 8 or 9 years ago.  

Best Wishes To All,

Brooce, WLP 

I spent nearly 3 hours out in an open field yesterday running tests on the Whole House 3.0 transmitter.

I purchased this transmitter at retail from a seller on Amazon, so what I tested was one as sold to the general public, not one handpicked by the maker or importer. 

Tests were taken with an accurately calibrated Potomac FIM-71, the same as the units used by the FCC in the field, and also used by most broadcast engineers who need to do work with FM broadcast stations.  The readings then were also taken with a ZTechnology R-506 which is used by a wide variety of RF engineers in dozens of applications and is also the "new" technology often used by the FCC for tracking down illegal operators because it can output to a laptop and also synchronize with a GPS unit and compute exact field strength from varying distances, etc. Needless to say I just use mine for manual field strength readings.  BTW, if you were to buy a new R-506 with its calibrated antenna the price is $13,000.  Each device was used with it's own calibrated half-wave dipole antenna.  Antenna factors were applied as appropriate, as well as cable loss, etc.  All readings were so close between units the differences were negligible.

Documentation on this very forum has shown FCC documents where these exact devices are used and referenced in filed complaints. 

The test site was a large open field.  The nearest building as at least half a mile away, the nearest trees were many hundreds of feet away.  The Whole House transmitter and the FIM-71 receiving antenna were at 7 feet above the ground as specified by Potomac.  It is worth noting that the receive antenna on the FIM-71 was horizontal for all tests (it's a half wave dipole adjusted in length for the frequency) as this is what it is calibrated for, I did however take readings with the transmitt antenna both vertical and horizontal.  You will see that, at least at 3 meters, antenna orientation has a huge effect on signal. I am posting all readings in uV.  You may convert to mV if you like. I was testing at 92.7 MHz, the frequency that showed a nearly imperceptable reading of background noise effect, somewhere around 1.5 uV/m (so technically you might subtract 1.5 uV/m from my numbers but it really won't matter. 

Here are the results, followed by some more comments.

At three meters, transmitter in "US power setting":

With Transmitter antenna vertical: 382 uV/m

With transmitter antenna horizontal: 1102 uV/m

At three meters with transmitter in "Canada power setting" (lightning bolt icon showing)

With transmitter antenna vertical: 4950 uV/m

With transmitter antenna horizontal 17775 uV/m

There are your basic tests at three meters between transmit and receive antennas.  I then did a quick range test using the Tecsun PL310 as long as I was in an open area. I didn't have the ambition to run a marathon to various points so I went out to 220 feet.  At US power at 220 feet signal was readable only by positioning the radio for the "hot spot" where the signal was strong and clear.  Now, this was directly broadside to the transmit antenna in a horizontal position.  As I walked around so I was at an end of the antenna (e.g. with the transmit antenna pointed at me) the signal was gone by about 100 feet.  So in horizontal position, as expected, the signal is quite directional.  The above tests were all done with just the transmitter on, running on new alkaline batteries, with no other cables connected to it.  But I noticed something a couple weeks ago while playing around with this transmitter out in the yard that I was curious to test out here in the open.

Apparently connecting any cable to the transmitter increases it's RF output. I'm guessing that connecting, say, an audio cable to the line in jack, the common (ground) of the audio cable acts as a counterpoise to the antenna, as there's quite an RF output jump just by simply plugging in an audio cable. Per haps it's one of the other leads in the cable acting as additional antenna, I don't know. And it also seemed to somewhat negate the effects of the horizontal or vertical antenna.  With the FIM-71 reading 382 uV/m with the transmitter in low (US) power and the antenna vertical, I plugged in a 4 foot audio cable -- 1/8 inch stereo to 1/8 inch stereo, and the output jumped to 4050 uV/m and this is just with the audio cable hanging down from the transmitter.  I was able to vary the output greatly just by changing the position of the audio cable in relation to the antenna.  I then tried it with the external power cable.  This is a short USB power cable provided with the transmitter.  Same effect, except not quite so dramatic of an increase. 

Then I though, what might the field strengh readings be at 10 meters? In high power, the secret "Canadian" setting, with the antenna horizontal it was 11475 uV/m.  Switching it to low "US" power the readings at 10 meters were 360 uV/m with the transmit antenna horizontal, and 112 uV/m with the transmit antenna vertical.  Just in case you're curious, with the provided long wire antenna (that has the warning not to use it in the USA) the field strength went to 17775 uV/m in the high power Canadian setting.  Although I wasn't really prepared to test this as I had no way to hold the antenna wire in the air so I just let it hang down from the transmitter.  Also as it was a breezy day the field strength varied as the antenna swayed in the breeze.  Had I been thinking I could have plugged the audio cable back in to see what I got!  Probably if the antenna were held up above the transmitter and the audio cable was straight down as a counterpoise I could really have had some power going!

My conclusion has to be that there's simply no way this is legal in the USA. Although, it's certified.  Makes me wonder exactly what the certification process involves.  Now, the Potomac FIM-71 indicates the margin of error for these tests at 7 feet above ground level is 18%.  So, in US mode, with the antenna vertical, and no audio or power cables plugged into the transmitter the reading is 382 uV/m. Allowing an 18% error in favor of the transmitter being legal (FCC documentation on this site shows the FCC always factors maximum margin of error in favor of the station) that still leaves us with 325 uV/m which is still above the limit of 250 uV/m. Then again, the margin of error could easily go the other way and be 439 uV/m, or somewhere inbetween. Whole different ball game if you flip the antenna to horizontal. Then it depends on if you're reading off the null ends of the antenna, or broadside. I didn't take any null end readings but I'm sure those readings would easily be legal.

Then, just for fun I took the transmitter up to my studio (second floor, old wood house, easily 20 feet above ground level) and set it in a window.  Then I set up the FIM in the backyard.  I was just sort of goofing around here so I didn't take any real readings, I just wanted to be able to see relative changes in field strength, but I was completely amazed at the HUGE difference in signal strength that could be induced sy simply plugging in the audio cable, and the differences between plugging it into an iPod compared to plugging it into a CD player (RF was quite a bit higher plugged into the iPod than a CD player). Or how simply moving the transmitter a foot to the left or right, moving the antenna to various positions horizontal, diagonal, vertical.  Setting my wire glasses next to the transmitter even made a difference. I tried probably 20 different things.  Moving the transmitter, moving the antenna, setting different things next to it, plugging it in to the ipod, then the CD player, moving the cable around, etc.  Every thing I changed changed the field strength.  Now, clearly I could have been simply been changing the direction of the signal, as well as varying the output by providing a counterpoise.  I finally quit because I had to run up two and a half flights of stairs from the studio out to the backyard and back and I got pooped. 

Trying to predict results, effectiveness, coverage, etc from this transmitter, and I suspect all Part 15 FM transmitters is a shot in the dark as a countless number of variables will effect virtually everything. 

So of course now I can think of a thousand different test combinations, but I'm done with this transmitter now.  So if anyone would like to buy a slightly used Whole House 3.0 at half price let me know :)

It will be interesting to see what the Decade CM-10 has in store for me. 

Tim in Bovey

OK.  Let me try to explain this...

I have a trusty Maxell P-13 FM transmitter.

Not the greatest thing in the world - but it's

teeny and is a very good point to point transmitter

for in the house.

I used to have another one but I destroyed it.

Here's what happened.  The P-13 uses 3 AAA

batteries.  They last a while and then they run

down.  I thought I could attach some wires to

the battery terminals.  Then I could run those

wires out to a power source that would last longer.

Such as - 3 D batteries in their holders.  The voltage

would be the same. It would run a lot longer.  Heck -

there isn't even a power supply involved here.  It's

just some bigger batteries.  I sounds like a good idea,

right?  The transmitter would just take the current it

needed and go for a longer time.

Like I said before...  Right?

Well, no.  It didn't work out that way.

I hooked up the batteries and this particular

P-13 never worked again.  (The polarity was

correct.  I'm assuming there was no reverse

polarity protection on this kind of item.)

It was as dead as a door nail.  (Whatever that

means.)

One trusty P-13 into the wastebasket.

My friends said that shouldn't happen.  I

agreed.  And then I thought - the device's

teeny chip (surface mount, whatever) countn't

handle the high inrush currect.  It just wasn'ty

designed to do that.

But I didn't quite believe the above.  And I 

actually blew up a few other small devices,

some good MP3 players and such.  

I have to go. 

What do you guys thinK.

Brooce, WLP

I need some help finding a FM tranmitter that has great quality, and does not leak into other frequences like I have heard this one does. I would also like a transmitter with good range (Under a mile) This transmitter looks the best to me and I would really apreciate anybodys imput. :) 

Some time ago someone (either Radio8z or Rich) posted the math necessary to calculate the actual voltage applied to a radio by a given field strength.  I can't find it anywhere using the built-in search function, so I was wondering if that someone could repost it.

I've found a bunch of equations on the web, but I'm hoping that those in the know could simply them for a standard monopole such as a car antenna.

I generally use a factor of 2.5 (I remember it was around that for the examples used in the original post, i.e., a field strength of 10uv/m will induce a voltage of 4uv into the radio).

I bought a 4 channel FM Transmitter for $6.00 at a Family Dollar store a few days ago.After I get a chance to evaluate the transmitter, I will post my review here.

Check out the video's for this transmitter/Watch.  You can get this for $1.00.  Only Downside is that it does NOT have a 3.5 MM jack.  Instead it does have a mic.  There is even a video demo of this.  It actually keeps time too.  Could be a fun transmitter to play with.  An easy way when you shop for your Wife to find you too or for the Wife your husband.  They could transmit and you trace the signal and as it gets stronger there they are.  Neat.

http://pocketcalculatorshow.com/nerdwatch/casio-tm-100-transmitter-watc/

Jeffery Gill started this petition for increased power on the AM BCB and here is the companion to the original petition. As I've been googleing to try and find any more possible petitions and rule changes in store for either part 15 AM or FM. This link may be of interest to us as there is already work in progress for an increase in the extended portion of the band as well as forming a possible NEW service for AM. Since FM is unlikely or at this point not within reach we may be able to work with all part 15 websites (Even HB) to achieve a common goal and interest. HB has always been king of AM so maybe this is something they may want to help with. Why argue about FM when we already have folks who are pro AM. Maybe we should work with them. After all I'm going AM in a few days because of the uncertainty and gray areas with part 15 FM Today. Check out the link:

https://www.change.org/p/william-t-lake-media-division-federal-communica...

Does anyone have experience with the GOgroove FlexSMART X2?

I have one in my car. I have been using it on 92.7. The other day I tuned to 92.5 and heard what I was listening to on 92.5, but distorted and very quiet. That makes me think it may not be meeting the 200 kHz band requirement of 15.239.

I got a new iAM transmitter I'm trying to get to go at least 1/4 to 1 mile.  I have a restriction where I can't put up an outside antenna by drilling holes in the house.  The TX is in a wood house next to one of the outer walls and the room has two windows. I have the wire going up the side of the window with a slight L at the top as I could not get it to go 100% vertical.  The transmitter goes out about 300 Ft and I start to hear noise on my boombox at 1630 Khz.  I could not walk too far as there is a busy highway so I don't know if the signal would come back clearer if I had walked away from the power line above my head at the curb where I would have to cross the street to go further.  Being legally Blind I really didn't want to cross it because it is on a busy highway.  I thought maybe if the signal didn't start to fade at 300 Ft it would have got closer to 1/4 mile like I did with my FM transmitter.  I'm trying to get to a few houses down the road to attract listeners when I do advertise.  But 300 Ft won't get me many listeners.  How did you guys get your AM transmitter to go further than 300 Ft from an inside antenna?  The window is painted shut because its an old house 200 yrs old.  I thought about wrapping the wire around a lamp cord to try and make it do sort of an inductance kind of carrier current.  If only I could get the signal to follow the power line I'd be set with this TX.  I also looked at the Golddar DXR 500 antenna which was supposed to be for receiving.  Its less than 3 meters long and since its metal it may do better I don't know.  It would sit on the desk and I could move it around a bit in the room to get better range.  It has a clip at the end of a lead wire which could connect to where the wire would connect.  Still wonder if that would work?  Any good indoor antennas better than the wire?

My first question is: How do I know that I actually received a Decade CM-10 for the USA market?  I bought it right from them, they shipped it to me in the USA, so I assume they sent me the right unit.  However, today's tests do not lead me to that conclusion.  Is there a way I can actually tell?

I set up exactly as I did in the Whole House 3.0 test. Same field, same equipment, etc. So read that write up if you're concerned about the setup. I used the Potomac FIM-71 meter and corroborated my readings with the Z-Technology R-506. Not nearly as many tests as with the WH 3.0, as fewer options to experiment with (Have to have a power cable, and no power level switching).

Note that the power supply with the CM-10 is required for use, no adapters, batteries, etc are provided.  The WH 3.0 I tested with batteries.  So any effect caused by having a power cord attached is a requirement with the CM-10.   Adding any cord to the WH 3.0 greatly increased it's output, whether audio or power cord, even when not connected to an audio source or power. 

All tests taken with the receiving antennas in horizontal polarization.

At three meters the CM-10 gave me 3375 uV/m with the transmit antenna in a vertical position.  With the transmit antenna in a horizontal position the field strength at three meters was 6300 uV/m.  Clearly both are well over the legal limit of 250 uV/m at three meters.

The power cable for the CM-10 does have a ferrite choke on it an inch or so from the plug that goes into the transmitter.  Also the power supply itself is not a wall wart as such, but a lightweight switching supply that has about 3 feet of cord on either side, one to the outlet, on side to the transmitter.  There is no continuity from the plug for the transmitter to the power outlet plug. So any counterpoise effect would be with the three feet of cable I imagine. 

I did notice that the output varied quite a bit depending on the location of the power cable.  By moving it out diagonally from the transmitter the field strength would vary.  The readings above are taken with the power cable hanging straight down from the transmitter.  Remember, transmitter and receiving antennas are at 7 feet above ground as specified in the meter manuals. 

I was clearly expecting this unit to give me much more close to legal limits. I couldn't remember the Canadian limits or I would have tested for them.  These readings are not that far off from the WH 3.0 when it has an audio or power cable connected to it. Adding an audio cable to the CM-10 didn't make a noticeable difference, but then again it already had a power cable.  And adding either cable to the WH 3.0 made a big difference but once one was added, adding the other cable didn't change things much. 

I took my first reading with the FIM-71 and was so surprised I doubled checked the batteries (they're new) and calibration three times, and took the readings three times, all the same, before setting up the R-506 to corroborate. Same readings. 

This is why I wondered if perhaps I received a Canadian unit. How do I determine this?

TIB

I was surprised to discover that this kit is still available:

https://www.tubesandmore.com/products/K-488

I built one of these probably 30+ years ago. Same kit, same seller.  I actually used it to play old radio programs into my collection of vintage radio sets. Then I loaned it to my bosses daughter who was doing a school science project on radio and used it to broadcast across the classroom. 

Interesting to ponder if this is Part 15 compliant.  I can't find the one I had. Probably buried in the attic someplace. Might need to build another. 

TIB

Today I put the Coaxial Dynamics RF meter on the two FM transmitters.  I used "slugs" in the meter specifically made for my purposes, as slugs for these frequencies and these low powers are not very common. Power read from antenna connection to ground on circuit boards inside the transmitters.

The Decade CM-10 gave a solid 2 mW out. Nothing else to test.

The Whole House 3.0 gave 2.2 mW on the USA setting.

On the "secret" Canadian setting the power jumped to a whopping 310 mW output!

Readings taken at frequency of 92.7, into a 50 ohm dummy load. Can't say for certain that 50 ohms is the actual design impedance output but it's pretty much the standard and either way the relative readings would be accurate.

Worth noting that I was testing the WH 3.0 with brand new batteries.  When plugging in the power supply (not the one included, as that didn't work) there was a slight increase in output, maybe a meter needle worth.  The USB supplies are 5 volts, the batteries make 4.5 so that little half a volt pumps it up just a little. 

Now, remember this can have some bearing on the final field strength of course, but it's how the antenna uses the RF power to get it into space, and especially how other cables are connected and arranged.  These readings were taken with nothing connected to the transmitters except power, and the WH 3.0 was also tested on just batteries with no power connected with similar results.  Not that I was expecting any changes as this was with the meter hard wired to the outputs. 

So, that's that. 

I know have two FM transmitters for sale at half price. I believe the WH 3.0 is spoken for. The Decade CM-10 is up for grabs at half price, $100 + shipping. 

TIB

I was at the habitat for humanity store the other day, and they had a pair of those "wireless phone line" extenders for $2.50.    I picked them up and brought them home, thinking I could fake it into sending serial data, ethernet, or something like that.

And then I thought about it-- I'm pretty sure they're "wireless" in that you don't have to string wire between them.   Also pretty sure they inject the signal into the house wiring.  I don't know that this unit is one of those for sure, but the size of the transformer and the lack of any clear aerial makes me think it is.   I'll be playing "hunt the datasheet" later on to see if I'm right.

If it is, I wonder if it'd be possible to cut out the POTS stuff and use it as an injector for carrier current AM? 

Suddenly it dawned on me last night that I had another Part 15 FM transmitter.  About 10 years ago we bought one of those little transmitters for the sole purpose of plugging it into the stereo in my home office, where I could play Christmas records on the turntable and transmit them to the radio in the kitchen while we were making cookies!  And sure enough, the little transmitter was in the drawer where I left it back then.

It's a General Electric EWT-950 FCC ID NZTSF-140.  I'll attach a photo if I can figure out how to do it again.

I thought, what the heck, I'll take this out to the test field and set up all my gear again and see what kind of poop this little bugger puts out. BEsides, I wanted to do tests again on the Whole House 3.0 simply because I have a hard time believing it's THAT far over the limits.

Anyway, got everything set up "by the book" as before in a wide open field.  This little GE unit runs on two "AAA" batteries.  Has no jacks, connectors, or any sockets in it, just a 15 inch built in audio cable with a 1/8" stereo plug on the end.   It's got the power button and a frequency select switch with thess "zones" 88-92, 92098, and 98-108.  AFter you set the range switch there's a tiny tuning dial on the side.  I used the Tecsun to lock it on on frequency.

So, what's the field strength you say?  At the standard 3 meter test range output was 61 uV/m.   As you know the limit is 250 uV/m at three meters.  This is so legal it's ridiculous!  This does explain why it had a hard time getting clear music to the kitchen from my office, through one wooden wall, and a distance of maybe 20 feet.  LOL. 

As long as I had the gear out I thought I'd double check the results for the Whole House 3.0.  Yup.  It's just as illegal as it was a couple weeks ago.  More so, actually. I tested at 99.5 (I used 92.7 last time) another very dead spot on the dial. Readings were consistantly higher.  I'm not figuring and typing them all out, but they were all higher.  Which I guess makes sense as with the little antenna on this transmitter, the higher you go in frequency the closer the match for the small antenna.

I was still going over in my head how the two certified transmitters I tested were so far over the limit, and trying to figure out if there was some anomoly that would have made my tests inaccurate so I was itching to do it again. Same results. 

So, FWIW, TYG. 

TIB