So I would like to use the SStran AMT3000 in the longwave band, to achieve this C30 a 180 pF capacitor must be changed to a slightly higher value.

The pll with 180 pF cap installed will only allow the amt3000 to go as low as 350 KHz, anything lower and the pll won't lock on to say 170 khz.

So i did a search for a 190 pF capacitor, hmm wasn't many to choose from, so what gives?
Should i search again or is there a value slightly higher than 190 pF?

I am sure the part exists, maybe google isn't my friend anymore.

My idea is to transmit on 170 KHz LW using the SSTran even though the FCC rules allow for 1 watt, i would be happy with the 100mW -+ into a 50 foot vertical.

And I would have the Talking House 5 handle 1620 KHz duties.

I am wondering if it would be better to install a mica compression trimmer cap with a value range of 190 pF to 760 pF. The original cap is ceramic.

If you want to run your transmitter at full legal power, do the following:

1) Take apart the unit by removing the eight screws on the back and front of it.

2) Locate the power transistor (Q7) and remove it. My unit had an NEC 2SC3355 in it. I was able to locate mine by getting a number off it and using a rudimentary schematic I found on the net. This is what drives up the power on the claimed Rohm BH1415F FM IC. Notice the orientation of the transistor so you can locate the base from the emitter and collector.

3) Put a jumper from where the base of the transistor was connected to a point on the antenna trace. I soldered to what is marked as C45 on the schematic. From what I could tell that coupled the signal to a matching/filter network.

4) Shorten the supplied rubber ducky antenna. I unscrewed the external plastic cover off mine, then started to cut off short pieces of it until I got a reading on my spectrum analyzer under 48dbuV at 3m. I basically cut the antenna in half. I shortened the antenna because I still got a reading of 62.32 dbuV (1306 uV) at 3 meters which is over the limit of 47.988 dbuV (250uV) at 3 meters.

My transmitter was laying in a pile of junk collecting dust. From what I remember, it sounded muffled. I've read that the preemphasis isn't set correctly. Still need to hook up mine and see how it sounds.

Rock On

How did I do?

I am in need of some help from someone who owns the AMT5000. I left the instructions for mine at my cottage 150 miles away. I need the DIP switch settings for setting the frequency. I would have thought I could find this online at the manufacturer's site but I have done a number of searches with no luck. If you happen to have this information handy it would be much appreciated. I need to change the frequency for operation at this location. Thanks!

Hot off the press:

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

TIB

You better pour another cup of coffee...

Probably the number one thing asked about a Part 15 transmitter is range.  Be it on this forum, or any of hundreds of other forums where radio and electronic geeks gather.  From Christmas Light Show builders to would be community broadcasters.  It's easy to see the most often asked question is something like "What is the Range of the XYZ Transmitter". Or "which transmitter will give me the best range".

Here's the answer.  If it's a LEGAL Part 15 FM transmitter the answer is "they're all the same" and "it depends".

We all know that FM is limited to 250 uV/m at three meters.  That amount of field strength is just that. It's 250 uV/m at three meters.  Neither the FCC nor the laws of physics give a crap if you reached that limit with a watt and a super crappy antenna and a ton of line loss, or 2 nanowatts and a 10 element Yagi antenna.  It doesn't matter if the antenna is at 5 feet, 10 feet or 100 feet in the air.  As long as it's not over 250 uV/m at 3 meters it's legal, and that amount of signal will go so far, period.

Then comes the "It depends". 

When I do range tests with Part 15 FM transmitters, (and I really don't anymore) if they're legal level or below, I walk from the transmitter with a fairly decent receiver in an open field.  The legal ones poop out between 200 and 300 feet. The few range tests I've done with over the limit transmitters that cover several blocks obviously require me to either walk a lot, or drive. Now you've introduced a lot of environmental factors. Buildings, trees, street signs, the list is endless.  The reception you get here, could be better or worse 10 feet to the side. Or under that tree. Or away from that tree. So it's really an exercise in futility. Unless you happen to have access to an open area a mile square. But then it's not a "real world" range test. 

Then it completely depends on the receiver being used. I've casually tested both AM and FM range using a wide variety of radio receivers, from those in diffeent cars and trucks to different portables from communication receivers to $5 handheld transistor radios, to boom boxes to high end stereo receivers. "Hey, I get get 450 feet"!  Well, with THAT radio anyway.  I only get 66 feet with this one". So again, range tests are folly.  People always try to quantify with something like "600 feet to a good car radio". How do you know you have a good car radio? Have you compared sensitivity to all your friends cars? Maybe you have two cars and one is better than the other, but neither is nearly as good (or bad) as your neighbors?  And you can't go by specs in the manual, either. That doesn't take into account age, damage, corrosion on the antenna connector or the antenna ground to the cars body, or many other variables.  Did you know car radios are somewhat directional? It's true. The radios are designed with AGC and other circuits to smooth out reception.  But depending on the car's antenna, you have some amount of directionality that can be most apparent when trying to receive a weak Part 15 signal. Antenna on the fender? The cars body is the ground plane. Obviously there's more body metal in some directions than others, varying the pattern. Antenna inside the windshield across the top? Directional depending on the direction of the antenna. None of the "range tests" people want are using any sort of standard for reception. But again, in an open area, with a legal transmitter, the legal limit can only go so far.  It's like having three cars all traveling at the legal limit of 60 MPH and then saying "Car number 2 will get there faster because it's more aerodynamic". No. It won't Because it, like the others, is limited to 60 MPH.  Or saying "Car number two will get there faster because it has 50 more horsepower than the others". Doesn't matter. It can still only travel at the maximum allowable speed. The law makes them all equals.  In the case of Part 15 FM radio the maximum allowed field strength is the speed limit. 

Further, these tests -- even the field strength tests -- are done in a wide open area. So, lets say you have a legal transmitter measuring exactly 250 uV/m at three meters in the wide open.  What's that field strength going to be when you put it in your house? Is the signal penetrating a 100 year old wooden structure?  Is your house stucco from the 1950's with a wire mesh behind the stucco holding it together? Is your transmitter in a window? Does it have an aluminum frame?  Is your house covered in aluminum siding? Have a metal roof? Are you in an apartment building or office building with steel girders? Once you're out of the open area and in your house, in your neighborhood, surrounded by other buildings, trees, power lines, phone lines, home wiring, etc all bets are off.  You're going to have a wild squiggly RF pattern, and it's going to be dramatically attenuated in some directions and multiplied in others.  This makes any sort of range test basically useless.  And if the FCC should come by to check you out, they're NOT going to take your transmitter out into some field to see if it's legal. They're going to check and see if you're over the limit, and they may check in more than one spot! If you're over ANYWHERE, you're illegal. 

For the most part, all transmitters of maximum limit output (and trust me, you'll never find two transmitters with the exact same output, even among the same brand and model) will have the same range when used in the exact same circumstances. 

Lets think about antennas. Lets say you have a transmitter that gives you 250 uV/m at three meters with it's little whip antenna. You decide to put up a dipole for it.  You've now put up an antenna that's going to have nulls in some directions, and gain in others. Which means in some directions you'll have increased range making your transmissions illegal, and reduced field strength in other directions greatly limiting range. Lets' review the statement above:  If the FCC should come by to check you out, they're NOT going to take your transmitter out into some field to see if it's legal. They're going to check and see if you're over the limit, and they may check in more than one spot! If you're over ANYWHERE, you're illegal. So if you decide to put a dipole on your otherwise legal transmitter you WILL have areas of antenna gain that will make you illegal in some directions. If you think your dipole increased your range, you're right! And it did it by providing signal gain in some directions, while creating nulls in others. It increased range to some listeners, while decreasing it to others. Where that gain is, you're over the limit.  Think of a radio signal like a round balloon.  You have a nice circular pattern.  Then you squish it in on the sides. The balloon bulges out in a couple places, while it's squished in at other places. Just like a radio signal that's forced into a pattern with different antenna designs. You still have x amount of signal, you're just changing it's shape, or pattern. Just as you do when squishing a balloon.  This is an easy way to visualize how a typical commercial radio gain antenna works. A typical 100,000 watt FM radio station has a transmitter that actually generates about 20,000 watts.  The antenna provides the gain to get 100,000 watts. (this is a bit simplified but the concept holds) The gain antenna is squishing that signal.  Take your round balloon, set it on a table.  The table is Earth. Squish that balloon as flat as you can and notice that there's no round top anymore, but the sides have expanded and it covers more of the Earth. That's what a gain antenna does.  It focuses the RF that's shooting off into space where no one can listen to it and adds that power to the signal going out to the sides where the people are. Again, a bit simplified but gives you the general idea.

OK, so that got off topic a bit, eh?

So, there's some thought on FM range, and why doing range tests of Part 15 transmitters is really not relevant. 

TIB

I need help finding a decent part 15 long wave transmitter even if it's a kit.  I know what you're going to say.  North Country Radio makes one, but it has been discontinued.  I need something that will go up to 100 mW to 500 mW and it's going to be set to 165 kHz or 175 kHz.   I wish that iAM Radio would support the LowFER's part 15 broadcast community with a talking house AM transmitter that does not just tune the MW bands from 520 kHz to 1700 kHz, but also 160 kHz to 190 kHz, even if they can come out with a 2 band version of the TH 5.0. 

I would appreciate if someone can help me with this, supply a schematic, link to a kit or something.  My main LW (NFM) 175 kHz transmitter is off the air, and I am going to be running it back on the air soon when the time comes.  It's still winter time, but we are getting mild weather here in Virginia Beach, VA area.  

gccradioscience 

Adam E. 

For operation around 1600 KHz

Change these parts:

Change C23 from 820pF to 560pF.

C5 replace with 1800pF fixed capacitor, polycarbonate 1800J.

Remove L4, L5, L6, L7 and replace with a single toroid coil, 15 uH, 34 turns wound on a T106-2 iron core.

Set all S5 switch position to OFF.

 -- Mike

Just received this FCC notice through my SBE Chapter. it may apply to some of you as well:

"The Federal Communications Commission is requesting your assistance in disseminating the information below to your organization's members.It has come to our attention that unauthorized persons recently may have illegally gained access to certain audio streaming devices used by broadcasters, and may have transmitted potentially offensive or indecent material to the public. We believe that the reported cases involved unauthorized access to equipment manufactured by Barix, which some licensed broadcasters use for studio-to transmitter (STL), remote broadcast (remote) and similar audio connections. We understand that the unauthorized access to the devices may be due, in part, to instances where the licensee fails to set a password for devices with no default password, or to re-set default passwords on the Barix device.We urge licensees to take all available precautions to prevent future unauthorized transmissions. In many cases, there may be simple, practical solutions to prevent such situations from occurring. For example, we strongly encourage licensees that use Barix devices, as well as other transmitting equipment, to check and, if necessary, add a password, or reset existing passwords with new, robust passwords. Similarly, if a broadcast station experiences turnover in staff who had access to passwords, we encourage licensees to reset the password to ensure future security. We also recommend that broadcasters investigate whether additional data security measures, such as firewalls or VPNs configured to prevent remote management access from other than authorized devices, in some cases, could be implemented to preserve this potentially critical part of the broadcast transmission chain. If you suspect that broadcast equipment has been subject to attempts at unauthorized access, we also recommend that you contact the equipment manufacturer and/or a data security firm. We also suggest that you notify the FCC Operations Center at 202-418-1122 or FCCOPCenter@fcc.gov of suspected unlawful access.If you have any questions, please contact Lark Hadley, the regional director for the Enforcement Bureau's Region Three via WR-Response@fcc.gov.Thank you.Charles CooperFCC/Enforcement Bureau/Office of the Field Director/Field Director"

I myself do not use a Barix unit, but will be this spring as I add a second transmitter down the road. I can assure you I'll have security and complex passwords.  Although, who is likely to hack a Part 15?

Interesting, however. At the full powers I work for, we just purchased a third station (so I'm now  chief engineer for three full powers) and we feed the transmitter audio for the new station via Barix units. As did the previous owner. Now, I'm certainly no IT guy, and I don't know diddly about computer networking, but according to our IT guy, we now have our own T1 line that goes directly from our studio to the transmitter and it is not accessible via the internet at all, it's part of our own LAN and that's it. I don't understand it all, but that's what he tell me anyway. 

But, be advised.

TIB

Radio peoples-Has anybody ever come to a solid conclusion on how to open up the audio response on the talking House 5 standard version? I have read all the prior posts on this and there seems to be some contradiction on parts (C 301?) and what to use. I’m just curious as it would be nice to have a final conclusion with what parts to use and with pictures of the board so a person would know exactly where to put the part replacements that would really make a difference in performance - if possible.

I use TH 5 units here and for all practical purposes they sound fine with an added low end boost using a Radio Shack EQ but they still don’t sound like a broadcast station either.

I’m sure cost of transmitters between a commercial grade transmitter for broadcast use, and TH may have something to do with it!

On the upper audio end transmitting using a TH 5 and using a crystal detector tuner to receive the signal, the TH 5s are crystal clear and sound as good as FM.

I’ve seen several schematics of the TH 5 and early versions on line  and try to find parts layouts, but it appears there were many revisions with time it’s hard to tell what is what on the actual chassis a person has in front of them.

Radio Joe

So I purchased an am tube transmitter on eBay from a gentleman in Virginia who builds them. I paid a fairly high price, but I feel it's worth it. His design involved three tubes. It plugs into the wall, has a long wire coming out of the metal box, a nice audio cable as well. Had a post with nut  and washer for grounding. It can be tuned by a nice big knob from about 750 am up to 1100 am. It has a nice glow  from the tubes. Excellent audio for am. I'm playing old southern gospel music through it to my antique emerson radio. 

The range covers my small apartment building of about 16 apartment units. I haven't put a ground rod in the ground to see if that will extend my range somewhat yet, but I'm happy with housecasting really. 

There's not much worth listening to on am around here anyway. Talk, talk, and more talk. A couple classic country stations that play same songs everyday.BBN christian station to the north and that's about it. 

I really appreciate the fine American craftsmanship in this transmitter. I'll try to get some pics uploaded later.

I don't have sound boards and other contraptions, i just hook the audio cables to the pc and push the sound until it starts to distort, but honestly it's just as loud as the local talk am without distortion. Much better sound with music than my talking house, but the talking house range seems better. I use radio dj.

I plan on streaming old time radio shows thru it for the elderly neighbors.

Thought I would share.

As a longtime part 15er it has gotten to feel like there is nothing new to think about, but that all changed with the March issue of Radio which on page 16, RFENGINEERING by Jeremy Ruck, PE, presents the topic: Synchronous AM Boosters Could Help Revive Senior Band.

True, we have had the Hamilton Rangemaster1000 with a synchronous option, but I think I heard recently that that feature has been dropped.

While the article discusses the long history and modern advancements in synchronizing AM transmitters for operation on a single frequency... to de-tune the carrier beat-frequency and lock the audio...what got my attention was a very brief description as part of the textual caption underneath a photo of the original towers for WBZ in Boston:

"WBZ and WBZA were synchronized: the carrier was generated at WBZ, divided downward to an audio frequency, fed over a phone line, then remultiplied at WBZA to create a precisely locked carrier."

That's the only information disclosed in the article about what sounds like a wild and amazing way of achieving synchronization that could probably be accomplished as a part 15 do-it-yourself project!

So far I've tried to reverse-engineer this idea using my limited knowledge of a few things...

An AM carrier has a bandwidth of 10 kHz, so we need that much space in the audio band for our down-divided signal;

The audio base-band is 20 kHz, so we need half of it for our encoded carrier;

Special equalized audio phone lines are normally good for 15 kHz bandwidth, so our down-converted carrier needs to be centered within this space.

What I cannot guess is whether the carrier is pre-modulated with program audio or is sent as a pure signal with modulation injected at both transmitter sites and also synchronized (somehow).

Sound like fun?

The mention of crystals in the thread about syncronized transmitters reminded me...

I saw this a few days ago:

http://www.arrl.org/news/international-crystal-manufacturing-going-out-o...

I sure bought a lot of crystals from them back in my early ham days!

TIB

Fortune recently favored me when I picked up a box of electronics ‘stuff’ from a friend (to replenish my own ‘junk box’.)  I was looking for a case for a project and when I opened up one of what I thought were project boxes, I discovered that it was a Ramsey FM-25.  I did some googling and and have concluded that this is not a 25b or a 25a, but in fact a plain ‘25’.  I’m rather excited as I always wanted to work with this little transmitter, but never the time, or inclination to throw money down on what I unfairly considered a lark.  That has obviously changed with this discovery. 

Despite several days of searches and looking at A LOT of links, I have been unable to find a manual or any information about the transmitter as it seems pretty much everything is for the 25a and the 25b.  The couple of questions I had were 1) does anyone have source for the manual? And 2) does anyone have an idea of what differences there are between the 25 and the 25a?  They look rather similar from looking at the manual, but are clearly not the same device.Thanks in advance for any links or helpful information.

Regards,

Grant

Here at the KDX Control Desk located in the Vacuum Room of the Internet Building we have a single computer workstation that generates all the audio programming which is distributed by various means to a planned total of 5 amplitude modulated transmitters located at different locations around the building.

We are building a Central Remote Control Point in its own cabinet next to the computer for controlling carrier ON/OFF of each transmitter, and foresee building in as many other remote control features as possible.

In particular, by having our B&K Oscilloscope alongside the Remote Panel we would like to wire a selector switch to enable viewing the modulation of each of the (5) transmitters.

We are asking the part 15 community to suggest methods of tapping the RF antenna feed point of each transmitter and sending it an average of 25-feet by wire to the oscilloscope, without affecting the integrity of the tuned antenna.

Scaled down to Part 15 power levels would probably make this item to costly to use but the idea has been brought up here numerous times.  Maybe in New Zealand...

So here is a company offering a turnkey solution.

Click on image to view website...

Decided to dig out an old work of art and see about getting it fired up and working again.This LPFM broadcast I had built back in 1995 that started off with a Panaxis FME500 and soon went and built the SG to go with it.Not long went ahead and built the 1525 amplifier and a custom made case to complete the system.This thing sat for over 20 years collecting dust.It really needs to be cleaned up and feel is the reason for the erratic behavior.First,the PLL would not lock so ordered new 2n4427 transistors and trimmer caps for the exciter.Ran a test with the amplifier disconnected and now thankfully the PLL locks on selected frequency.This was good news since fining a new PLL IC seemed impossible for this unit.However,managed to find one on Ebay (I think) so ordered one just for backup.http://www.ebay.com/itm/222132344468?_trksid=p2057872.m2749.l2649&ssPage... it will work or not has yet to be tested.The original is a DS8907N,this one does not have the "N".The manuals for the Exciter/SG and amplifier are long gone sadly but managed to find the Exciter/SG manuals online.Now hoping to find the amplifier plans for the 1525 and hope maybe someone in this group has it? If not,found one for sale and could just buy it.This thing needs to be cleaned up but to me is a work of art.I am no electronics expert and must have been really motivated when I built this thing.It was quite an investment even for 1995 and letting it rot away seems wrong.I am still having issues with the PLL locking properly so after the trimmer cap replacements, new 2n4427`s and even re-made the 5 turn coil with tap.Also discovered that when it does lock,not getting a stereo signal.After looking over another SG photo online,quickly saw that the 4.864 mhz crystal was removed.It is beyond me why that was taken off so ordered a new one.I think it will function fine but still need the amplifier plans and get it cleaned up and working.Since the amplifier was only sold as "plans",made my own PCB back when radio shack sold etching kits.Those were the days !Thought to share this stuff after all these years in hopes someone else may be familiar with these particular boards.Jim

I am curious as to the typical broadcast frequency selected by folks using the SSTRAN 3000. I am working on modifications to increase the effective power output (within part 15 rules) and would like to share with others. My mods won't span the entire AM broadcast band, so I'd like to choose the most used segment of the band.

Mike

AB1AW

I can't find the manual.  I just want to run it

through my carrier current coupler.

It won't go far.  But I'm wondering what it WILL do.

Just for fun.  620 is blank here during the day.  (Nightime

it sure isn't ha ha ha!)  I'll do neutral (sp?) feed.  I have a mod

for the SS-Tran.

Thanks much

Brooce, Part 15 Hartford

I have an Inovonics 235 feeding a Sstran amt 5000.  Over the past couple of years, I've tried to play it by ear regarding the modulation.  I just got an Inovonics 520 AM mod monitor off of eBay.  On the 235 I am able to adjust the negative output from zero to over 100%.  I am unable to get 125% positive modulation.  When I adjust the pos output on the 235, I'm not seeing much of an increase or decrease through the monitor.  The positive modulation stays around 100%-110%.  There is a slight decrease on the positive when I turn the neg mod to 0%.  I can't get the positive to adjust to 0%.  Any ideas on what could be wrong.  Thanks

Audio is fed to 235 as follows:  Arrakis Arc 8 console --->Whirlwind IMP Line Combiner --->235

I am now even more frustrated than I can possibly describe in a polite manner. I've tried everything I can think of plus what has been suggested. No matter what I do I get 0.144v when measuring RF input current, and 2.688v when measuring RF input voltage. This is across the entire range of  Based on the formula this means the transmitter is putting out less than 4 mw (0.0387072). I get this value across the entire range of tuning C1.  As Carl suggested I confirmed that S1 was not connected (it never was). I powered off the xmtr during every change just to be safe to the transmitter.  I tried the RF peaking procedure using  each of the three jumper positions suggested by the manual (S8,S9,S10). Same results.  I also replaced this jumper with a brand new one in case the first one was bad and again went through the peaking procedure using all three jumper positions again. Same results. I inserted a capacitor in the antenna line. I went from feeding the coax to just a long wire again. I changed from using my cheapo Extech VOM to my Fluke 110 DMM. I also tried adjusting c25 to see if the readings changed. They did not. BTW I still don't get why the manual says to keep the slot of C25 lined up front to back but since you can rotate this cap several times the manual doesn't mention how many turns up or down this cap should be rotated when the slot is lined up front to back.  Two days ago I was getting the best range ever even getting over the mountain  behind my house.  Now I don't even get down to the end of my driveway (800ft).. If you can see it on the attachment, that longes red line was over 9000 feet. How it got over the mountain and I could hear it baffles me, but anyway that was 2 days ago, not now.  Any ideas?

Apr 18, 2017 16:14:26 GMT -4 carl said:Oh, That's Right, the CoaxOver the course of the back and forths I lost sight of the coax and wasn't sure it was still in place or not. Now that we know, I'm guessing that all that coax is swamping the signal with capacitance that is throwing it out of the designed range. By adding a 20 pF or other small value of capacitor in line with the antenna you might be able to get the tuning back into range.