Anything to report on Grain Industries GI100/1000 Transmitter? Pros or cons?

Well I'm still struggling with a technology that I intend to replace.

My STL (Studio Transmitter Link) to my AMT5000 from sstran.com is done by C.Crane FM Transmitter and Panasonic Receiver, and it is working.... sort of.

But the problems are more complicated than you want to know. This will be book length, so plan to stay up all night to read this.

Better yet, I'll skip the whole part about why I switched from Wholehouse 2.0 FM Transmitter and ended up moving the C.Crane because of intense multipath disturbance everytime I walked anywhere in the house.

Putting all those other issues aside, the present problem is static. Where does it come from?

If I step on a certain floor-board while walking in the house it sends a vibration to the C.Crane which produces a splatter of static.

If I physically pick up the C.Crane and move it, static goes crazy until I set it down.

What might be the problem? I guess there is a loose connection; a cold solder; a broken intermittant wire, which gets disturbed.

Is the C.Crane easy to open and fix? No. It is like many cheap junk products which are not intended to be maintained by a reasonably capable human being.

The Ramsey FM25B is superior and I wish the neighbor who stole mine would give it back.

you should consider adding an AGC bypass switch, redesigning the output stage of your iAM for Class E mode (if possible) and adding a +4dbu professional input to your iAM. maybe a redesign of the external ATU to make it more efficient in terms of power transfer to the antenna with maybe an air coil / cap design like the procaster or toroid / cap design like the rangemaster.

maybe one of the forum posters here who is on good terms with dan (calling MRAM) can point him to this post or otherwise suggest these modifications to him.

it should be easy to add +4dbu to the iAM and redesign the ATU, not sure about modifying it for class E maybe Phil B can chime in on that one and better explain modifications for going from the class "C" of the iAM to Class "E" like the amt5k.

these mods would most certainly make an already great little tx system even better.

the iAM now modulates to +125% but it's ATU and Final output stage is still very inefficient like most certified part 15 am transmitters and there is room for improvement there.

maybe since the ATU when attached is considered the Final RF stage the iAM can be configured to bump up to 100mW TPO input to the ATU (final RF Stage) when ATU mode is selected. and when switched to the internal wire antenna can be  100mW input to the final transistor. since when Selected the ATU is the Final it should be legal to put 100mW input to the Final Stage being the ATU not the final transistor in this case. gotta squeeze every little legal drop of Milliwatts we can get out of these things. Efficiency, Efficiency, Efficiency. that is the nam,e of the game. we are limited to 100mW and a 3m antenna and have to get every last drop of efficiency out of the final RF stage and the antenna tuning design.

this already good little transmitter system has some greater potential if radio systems will consider the input from the part 15 community and make suggested modifications if technically and legally possible.

right now i am torn between the iAM because of it's unique system design and fcc certification and my SSTRAN amt5000 because of it's pro inputs, pos. modulation capabilities, and class E output stage coupled to an efficient ATU design but it's only drawback is it is not FCC certified which means more scrutiny from an inspecting agent and some agents take a dim view of kits while others don't.

not sure how denver FCC which i live only 10 minutes drive from would view a kit transmitter.

presently the iAM with it's Class "C" mode applies 60mW to the External ATU connector and the AM double loopstick tuning design of the External ATU is very inefficient. if the mode was changed to class "E" 90mW would amke it to the RF connector and if a Efficient ATU design were employed then more of that power would make it to the 3m antenna which would garner greater range. my tests showed that under similar circumstances the SSTRAN 5k generated a higher F/S than the rangemaster or TH5/ATU combo when mounted in the same circumstances.

i Used a FIM to tune the SSTRAN to resonance though and didn't follow phils instructions on the antenna tuning portion and then proceded to follow phils table to tune for 100mW input. under those conditions the SSTRAN 5k ran rings around competing transmitters that i tested it against for the same installation location.

these are just some thoughts. i am all for pushing the legal/technical limits of part 15 without breaking them and remaining FCC legal.

that leaves us with improving efficiency of the antenna and RF stage.

just imagine an iAM runnning class E mode at +125% using an efficient ATU unit with it's unique system design. it just might blow away all other part 15 certified transmitters out there in terms of performance.

i know in reality i can wish in one hand and crap in the other but i can certainly dream about it.

in terms of audio quality the amt5k, rangemaster rev. b, and the iAM all has similar audo. raw peak F/S (i own a calibrated FIM) the SSTRAN blew them all away.

I might be talking crazy talk here but...

I know often we talk about how to distribute audio to a remote network of transmitters. Many will use an FM Part 15 to distribute audio to part 15 AM transmitters, or use internet, etc.  Suddenly, while answering Radioboy's blog this morning, I thought "Hey, why not a Marti unit?"

For those who don't know, a Marti is an FM transmitter that is used by commercial radio to broadcast from a remote location -- the high school basketball game, sale at the hardware store, grand opening at the super market, etc. They are sold in various frequencies, and they've been in use for probably 40 years or more.  Marti units go way back to tube models, and of course there are modern solid state units as well. They're built like tanks and run on AC or 12 volts. Generally 20-40 watts depending on model or condition.  They put out a very clear FM signal (not stereo) that is used for commercial broadcasting. I've used one in the biz since the 70's. I use one in my present day commercial radio broadcasting.  It's presently putting out about 25 watts, we use a portable 1/4 wave antenna and get signal back to the station from up to about 10 miles out.  We do much better with the yagi antenna, or if we can get some height. This could easily send a clear signal to an unlimited number of Part 15 transmitters within a ten mile or more radius with the right marti transmitting antenna.  Although Marti units come with matching receivers -- all crystal controlled -- a typical $10 scanner from a thrift store will usually tune in Marti frequencies and can easily be used as the receiver at the part 15 transmitter.  The one we use at work is on 161.700 MHz and 10 miles away my cheap Realistic scanner picks it up at home no problem.

Now that so many radio stations are moving to other types of ways to do their remotes (mostly internet) Marti units come up on the used market pretty cheap, especially the older ones from the 70's (no one wants to haul them around).  They do require an FCC license but I believe that's a matter of filing out a form and sending in a filing fee.  They're considered "RPU Units" (remote pick up).  We have in a pinch used one to send audio to our commercial FM and AM transmitters from our studio when our STL or line to the AM was on the fritz.  This makes a Marti an STL (studio-transmitter link).  Obviously this would work, as it's done in commercial radio every day.

Plus a typical Marti has 4 inputs -- line and mic, so you could even feed remote transmitters and use the Marti as your mixer, too.  Feed a computer into one channel, a mic into the other, and you're on!  What you need is a Marti RPT-25. They're the least expensive right now it seems.  I see they're all over ebay from a few bucks to a couple hundred depending on condtion.  New ones are a couple thousand for a system.  But simple receivers at remote locations could all receive the signal -- you could have a very solid way to feed a huge network of part 15's with minimal cost compared to other options!

Tim in Bovey

It's becoming winter and the radio bug has me thinking about getting broadcasting --- finally.

I've managed to collect a few of the Talking House AM Transmitters this year (ahh 6 of them now --- version 5's).

My transmitter location is off grid.  No main line power.   We'll be running from DC power, solar fed to deep cycle batteries.

The Talking House AM units have some spify ground allegedly through the 3rd prong ground on the power lead.   Since I don't have such, can't supply such.   As I recall this is just electrical ground.

Anyone see issue with feeding the Talking House with a properly sized barrel adapter with just the positive and negative power leads?  Direct DC power in.

This is a shot in the dark. 

Does anybody anywhere manufacture

AM broadcast band crystals below 1000 kHz

anymore? 

This is for my LPB vacuum tube carrier current

transmitter, so it would have to be pretty strong -

it would have to handle the energy from the

first oscillator stage.   

I know there are crystals out there - you just have

to look for them.  I  think the answer to this question

is no.  But - I thought I would ask one last time. 

And - just for kicks - does anybody out there grind

crystals anymore?  I know some radio guys still do it,

but I'm wondering if anyone in this group ever tried it.

Bruce, DOGRADIO

Just a couple things I've done the past week that may be of help to someone.  Nothing to do with actual programming or transmitting, but more "office work".

I was thinking it would be nice if I had a separate phone for the station. I already work in commercial radio and have an unlisted home number to prevent "spirited listeners" from calling me at home, in the middle of the night (which for me is after 8 PM).  So I didn't really want to use the home phone.

I knew many cell phone services exist that are cheap and "pre-paid" (no credit checks, no bills) the cheapest I knew of was from ATT (around here anyway) that was $15 a month, but I felt I could do better.  A bit of web searching led me to "PureTalk".  They had solid coverage in my area, a very basic (VERY basic) flip phone was FREE (with NO shipping) and I got the $5 a month service, which is only good for 50 minutes a month.  But that's enough for people to leave a  message and I can call them back on my regular cell or home phone for free. For the cost of $5 a month I have a station phone number with a station answering message "Hi, thanks for calling Iron Range Country Radio.  We're either away from the office or busy in the studio.  Please leave a message and we'll get back to you as quick as we can.  Thanks again for calling Iron Range Country Radio".  Instant public communication and cheap too! And if I ever get actually busy it appears to be easy to upgrade the service plan and keep the same number!  Just an idea if you need a station phone. 

Second tip of the week (LOL) is Vistaprint.  You may have heard of them, they print business cards and tons of other stuff.  They offer "free" business cards.  If you haven't seen the pitch, you can get 500 free cards, paying only shipping. You have to choose from one of the stock free designs (there are many to choose from and they change every so often).  You have to be careful when you check out because they REALLY pitch the ad ons, and be sure to change it to the cheap shipping at the end.  You wind up paying about 6 bucks for 500 nice looking professional cards.  I have a batch made up as a nice station card, with my name, the email, all that on it.  Then, I also just made up a batch for Chiristmas that promote upcoming Christmas programming, reminding people that ads for in town people (those who can actually hear us over the air) are FREE, and encouraging submission of club announcements, etc.  I did splurge on these a bit and for $5 extra (I think) I added "foil" which gave some nice shiny foil details to the green cards, making them look very Christmassy.  I took them around to local businesses who left them out for customers and clients, hung some up on the bulliten board at the post office, etc. 

You wind up paying under 2 cents a card for 500, and that's 500 impressions you can make on people, and we only have 681 people in this entire town!

No, I don't work for Vistaprint, just a satisfied customer.  I've bought tons of business cards from them for various (some quite odd) purposes over the years. 

Tim in Bovey

Iron Range Country

This may be a bit beyond many broadcasters here technically, but it sure is cool. The Raspberry Pi, that tiny little computer for hobbyists and tinkers is capable of generating an FM signal. It's a hack and the software is a bit limited so far.

Total output on this is estimated at 14mw.

http://www.icrobotics.co.uk/wiki/index.php/Turning_the_Raspberry_Pi_Into...

That solution is limited to a mono broadcast.

Someone outdid them and created a stereo version :)
http://www.reddit.com/r/raspberry_pi/comments/14k5o3/raspberry_pi_fm_tra...

There are multiple videos on YouTube about this:
http://youtu.be/blvaYR6aYXA

Have we any Carrier Current gurus in the house that might explain my observations?

I've finally gotten my Radio Systems TR-20 with matching CP-15 coupler going. Transmitter needed work - turned out to be a shorted zener diode on the 12v supply as well as both oscillator IC's (nand gate and flip-flop) bad. Plus an intermittent crystal that, after warm-up, jumped to a higher (and non-standard) frequency. Anyhow, I ordered a few more crystals, and was testing out a couple of them to compare performance.

I tried the lowest (600) and highest (800) frequencies I had crystals for. The result was that at the lower frequency of 600KHz, I had almost double the usable range when compared to 800KHz. OTOH, while 800KHz is almost hum-free, 600KHz is significantly more hummy.

I imagine the lower frequency might couple more efficiently into the power line, and/or do a better job of jumping the transformers, resulting in a bit more range, but what would account for the lower frequency also being more hummy?

I also observed that, into a dummy load, the transmitter was putting out a bit less power on 600 than on 800, though it might be that my power meter (part of a ham antenna tuner) might just not be accurate at that low of a frequency. And it's possibly also a red herring.

we know on paper it takes 11nW to the terminals of a 1/2 wave dipole to produce 250uV / m @ 3m, but how much power does it take to produce canada's standard of 100uV / m @ 30m?

have not (or missed it) seen a topic covering this for canada's license exempt standard.

sold that LPB FM Stereo Modulator and i will be getting a Decade MS-100s (ANT) to replace my Broadcast vision, the BV will be pressed into remote site service via homebrew internet STL link.

just have a few more things to do to the studio and i will be done. need a second broadcast quality mic processor, a production library, and a Chez procaster, and some modulation monitoring for FM and AM at my main site and my studio / station will be complete except for adding remote sites as $$$ permit.

Greetings all from the UK

I read the following post with interest about a shortwave transmitter

http://www.part15.us/forum/part15-forums/transmitter-talk/ism-shortwave-transmitter-continued

My question is what kind of range have users in the USA managed to get?

I too can use this transmitter in the UK but ofcom state that the power output should be no more than

42 dBμA/m at 10 m

Could this number be converted to a mW power limit and if so what would that roughly be?

Or is there an estimate of range that a signal of 42 dBμA/m at 10 m would give?

Any insight would be greatly appreciated

Cheers

Are there any FM audio transmitters for 410 to 470 MHz?

Part 15 allows for a field strength of 200uv/m@3m for any type of use between 410 and 470 MHz.  That range falls on cable channels 55 to 64.  If FM audio was transmitted on one of the audio carriers for those cable channels, someone could listen to it on their television.

Trying to send an NTSC video signal with a field strength of 200uv/m@3m would not go very far.  However, if all that allowed signal was used for audio, it is only 50uv/m less than what is allowed in the FM radio band.

410 to 470 MHz overlaps the 70cm amateur band (420 to 450), so only the audio carriers for channel 55, maybe 56, 62, 63, and 64 would be “safe” to use.

Not all TV’s would like receiving that sort of audio.  TV’s that go to a blue or black screen without a NTSC video signal would not work.  TV’s that had to be put into an over the air or a cable mode would be difficult for people to receive audio with.  On the other hand, I have a LG HDTV that will show snow on analog channels, and it will scan over the air and cable channels and show anything it finds for both; it also has an easy way to manually add channels.  It will happily play audio on a channel where the video is snow.

The 50uv/m less than the FM radio band may be made up for in antennas.   Even with 410 to 470 being outside the UHF broadcast band, if I did my math right, it looks like an 8 bay antenna may have 6 to 8 dBd of gain at those frequencies.  (For comparison, the FM6, one of the last off the shelf FM antennas, only has 5 to 7 dBd of gain in the FM band.)

So, the trick would be finding a transmitter that could put out a horizontally polarized (to match TV antennas people have on their roofs) FM audio signal on carriers of 413.75, 419.75, 455.75, 461.75 or 467.75 MHz with a field strength of 200uv/m@3m.

Anybody seen the new version of this transmitter?
Looks good with some nice features.
www.wholehousefmtransmitter.com
Has many more features than the CCrane. Even selectable pre-emphisis and transmitter chip has limiting and mono stereo selectable and much better case to not break if you drop it.
Maybe worth looking at. FCC and IC certified. Looks like much better display also.

Mark

Anyone know the exact antenna wire length that comes with it

for a TH v5?

TIA...

I broadcast on 1620 AM and am quite happy with that, and I have no intention of adding an FM for mass consumption.  However ....

I am now providing audio for the public access cable channel in my town.  This costs me nothing except equipment to make it work, and I'm on in every household with cable TV which is pretty much everyone as there's no OTA TV around here. So I set up an AM receiver and some switching, cabling, etc to interface it to the TV system over at City Hall (the only thing they broadcast on public access is city council meetings twice a month).  The trouble is AM reception in the room where the equipment is located is marginal at best. The Dayton Am monitor I set up originally was so sensitive it picked up noise from every piece of equipment in the room.  After playing around with varying radios, getting a long cable to move the radio far away from any equipment, it's passable, but not what I consider good.  This room has a rack full of TV equipment, TV set, several computers, ancient flourescent lights, etc so the interference is horrible. Reception is fine in other parts of the building, but since it's a 100+ year old historic building, messing around in it too much is frowned upon.  If I could put the receiver in another room and run 100+ feet of cable, I'd be good but that physically wont' work out.  I do know that the interference is getting in through the radio reception, not in the audio cables/switching from the radio to the gear. 

I'm considering FM.  I've done no research at all on FM Part 15 transmitters.  All I know is range is quite limited and the rules are for field strength not input power.  City Hall is about 450 feet from the attic window where I have my AM transmitter set up.  It would be easy to set up an FM transmitter in this same window.  It's line of sight from my attic window to city hall, although by site a straight line would hit just above the office where I would set up the receiver, but it'd be mighty darn close.  Could I expect a Part 15 FM transmitter that doesn't cost a fortune to hit City Hall 450 feet away?  The receiver would be located up out of harms reach from bystanders and I could set up an indoor antenna if necessary.  I don't need stereo, but I need a solid signal and I think FM would easily get me out of the interference from stuff in the room zone. 

Is this a realistic expectation for an FM transmitter? And what would anyone recommend? this would basically be an FM studio to city hall audio link that I would not advertise the frequency, etc. 

I have a solid as heck AM signal there -- sounds fantastic once I get out of the room full of gear, but all that equipment is just too much interference competition for my signal.

Tim in Bovey

Iron Range Country

Anyone know off hand about Part 15 use on 450+ MHz?  Quick web search didn't help much. 

Experiments today on a transmitter I was working on indicates that a 1.5 watt transmitter into a dummy load, in my basement, on the opposite side of the house,  gives me a solid signal at city hall half a block away.  Makes me wonder about the possibilities of such for an STL from the station to the office at city hall where my audio enters the cable TV system for the public access channel.

Of course, wouldn't consider doing it if it isn't legal, but in the engineering world we're apparently doing a heck of a lot of "broadcasting" into dummy loads around the country!  I've never tested for any sort of coverage when using a dummy load before in any of the various services and bands I work in.  I was quite amused. 

Tim in Bovey

This is my very first scratch built electronic project. A 10mW 88 to 108 MHz amplifier for my low power fm transmitter. yes i still need to add a B+ choke and ground those unused solder pads to minimize stray capacitance and i might add one more pole to the LPF, then it's installation and off to the SA for the LPF to be tuned and then adjusted to comply with 250uV/m @ 3m.

for the armachair lawyers and kilocycle cops no i will not be running it full bore. it will be adjusted using my SA and compliance dipole for 250uv/m @ 3m from radiating antenna.

Came across this while looking for something else...

TEMPEST: ALL YOU NEED TO BE A PART 15 AM BROADCASTER

• No Transmitter required.
• No Antenna Required.
• No Mixer Required.
• No Soundcard Required.

This isn't a joke.. Well, actually it is kind of is, but it's for real nevertheless... "Tempest is a Program that uses your computer monitorto send out AM radio signals. You can then hear computergenerated music in your radio."

Utilizes "Hidden Data Transmission Using Electromagnetic Emanations"

Full description and free download: http://www.erikyyy.de/tempest/

AM STEREO .....

http://vimeo.com/22728658

Listen to this and see why I will do this somehow someway ......