OMG What am I going to do with this??
 

A friend brought me new toy to play with yesterday. Oh geez what am I to do with this??

I am now the proud (I think) owner of a McMartin BA-K1 AM radio transmitter!!

The transmitter came from a local station that shut down a few months back. My friend's dad bought the building, and my friend traded me this transmitter for a used Jenn-Air in wall oven.

Initially, we were going to sell it, and he left that up to me to deal with. It didn't sell, and I am returning to sea next week, so I don't really have time to try pushing it for sale anymore. He expressed interest in the oven that we were getting rid of, and told me he would be happy to swap the two.

Well heck yeah... why say no?

So now it's here, and of course I can't fire it up in any way. I'm sure it needs to be hooked up to 240, and I wouldn't want to mess anything up without having it looked over by someone familiar with these first.

So, I guess at some later date, I will have to investigate getting a license to operate such a beast.

In any case, it's sorta cool to have!

Very cool! Could probably be converted for use on 160M, or at the very least, you have most of the parts there for a "California Kilowatt" linear amp.

The transformers appear to be single phase, so they can be run in a residential setting without problem other than getting 240V power.

I wonder how hard it would be to convert it into a linear amp for the TV band?....It could be fun having your own pirate TV station on the holidays.

The building it will be housed in does not have electricity yet. It was supposed to this past month, but something else came up and I had to direct attention and money somewhere else. So, when I do get power in that building, I will make sure to have a 240 line run to where the transmitter will sit.

I gotta assume this baby uses quite a bit of current... the power transformer is enormous!! And WOW this thing is heavy! It must weight 700-800 pounds! You should have seen us trying to move it!

You can start up your own clandestine AM broadcast station!

It puts out 1000 Watts, probably consumes nearly 2000 Watts of power to do it.

Looking at a few Youtube videos, looks like it can be converted up to the 160M ham band, 1.8 to 2 Mhz. It's designed for AM broadcast 550-1700 kHz. Not designed for VHF TV frequencies. So it won't work for that.

Man, you got amazing friends.

Don't try to put that transmitter on the air; don't even think of it. I shouldn't have to mention this, but unlicensed operation of any radio transmitter is illegal and will get you in a lot of trouble with the FCC. I realize the person who suggested using the transmitter as the heart of a bootleg radio station was joking (I hope, anyway), but this is no joking matter. I'd sell the transmitter back to whomever you bought it from and forget it. If you have an amateur radio license, you will likely lose it when, not if, the FCC discovers you're operating an unlicensed 1kW AM radio transmitter.

No one who has ever done this has gotten away with it. There was an article in a 1968 issue of, IIRC, the now-defunct Electronics Illustrated magazine, in which the story was told of a bootleg short-wave station that used a 60-watt AM amateur transmitter, operating in a part of the 80-meter amateur band where US stations are not allowed, and a battered phonograph turntable. The station's call sign was WBBH, and it was discovered by the FCC shortly after it signed on.

WBBH was forced off the air very soon after and was never heard from again. However, the call sign WBBH is now used by a legitimate, fully licensed television station in Fort Myers, Florida. WBBH (TV) is an affiliate of the NBC television network.

The title of the Electronics Illustrated article which chronicled the short life of WBBH (the bootleg SW station) was "WBBH, the station with everything...except a license." The station had absolutely nothing in common with WBBH-TV, except the call sign.

I am sure it will be nearly impossible for a person to get a license to operate an AM broadcast transmitter, and even if it were possible, the fees involved in starting an AM radio station (tower siting, et al.) are prohibitively high. Leave broadcasting to the professionals. Again, this is no joking matter. The FCC takes an extremely dim view of anyone operating an unlicensed radio transmitter; the only exceptions are 0.1-watt (100 milliwatts) stations that operate under Part 15 regulations.

Of course I was jesting. Note the use of the word "clandestine"..geezzz...

If you have a General or better amateur radio operators license (I have an Extra Class) you can indeed operate that transmitter if modified to operate at 1.8 to 2 mHz, the 160 Meter ham band. So if you don't want to get at least a general class ham license, you might take it to a local "hamfest" sidewalk sale and sell it to someone who can legally put it on the air.

me liky alot ,,,, now why can't i run across stuff like that.

Man, Jeff is such a party-pooper!!

Yes, Jeff, I am well aware that I can't just plug this thing in and start using it. Thanks for your kind words.

I've already read a little bit about what it takes to start a radio station and the costs involved. Set up cost aren't as bad as one would think. However, this baby takes up a lot of juice... 4500 watts at 240 volts... it would be like operating an electric clothes dryer or hot water heater all day long!

I'm kinda intrigued about the idea, but I need an AM radio station like I need a hole in my head!

This item isn't something that can easily be brought to swap meets, either. This SOB is HEAVY! I'm guessing it's a good 700-800 pounds! It took three of us to move it with an appliance dolly, and it was NOT fun!

I'd probably stuff it somewhere in the corner of a (walk-in) basement or shed. While you might not be legally allowed to use it right now it still makes got good bragging rights. :thmbsp:

You just have to love gear that has a window to look at the tubes glowing...:D

Damn skippy!! :D:D

Might make a decent driver for reflashing getters, using either a fixed coil or a wand.

https://m.youtube.com/watch?v=lOenKVTYyRQ

https://m.youtube.com/watch?v=gQBmt-z0w9g

Most induction heaters that I have seen operate below the broadcast band (500 khz or so) but this transmitter perhaps could be modified for lower frequency,
:scratch2:


jr

Usually, having a decent antenna for 160 is harder. Especially for a kilowatt transmitter that expects a quarter wave antenna (like a tall broadcast tower). Oh, it can be done, but takes some effort.

Yep. I've played with 160 M by loading up my 80-40-20 vertical which is about 40 ft tall with a capacitance load on top. Using a big loading coil I made from some scrap city sewer pipe about 8 1/2" diameter with about 20 or so turns of aluminum ground wire and alligator clip attachments to find a match with my MFJ antenna analyzer before I put power to it. No more than 100 W applied to it by me though.

http://www.videokarma.org/attachment...6&d=1458415208 http://www.videokarma.org/attachment...7&d=1458415208

That sort of thing can be said for almost all of us here, one exception being Jeff. A quote from The Simpsons' Apu comes to mind: "Must you dump on everything we do?"

Anyway, that's a fine catch. And I thought my old desk was heavy at about 300 pounds.

Some impoverished peanut whistle AM station owners, mostly in small towns have had a moderate degree of success with short heavily top loaded arrays such as this:

http://www.star-h.com/docs/STAR-H%20...esentation.pdf

jr

Does your unit have the original (and scarce) 4-500 tubes in it, or did it get converted to the 4-400s?

Just looked... I could make out 4-400C on one tube, so I assume they are all the same. I did happen to notice online that 4-500's were about 500 bucks a pop. Looks like the 400's run about 300... at least the new ones I saw.

Used 4-400s and various substitutes are plentiful, as well.....4-500s not so much.

As others have warned, attempting to put this thing on the air for its original purpose (running an AM broadcast station) would bring you serious legal trouble. Only way to use it as-is would be to acquire a licensed broadcast station. FCC only accepts new construction permit applications during an "application window". They haven't had a window for AM Broadcast since 2004 and are not likely planning another one.

Last I knew, licensed radio amateurs could modify equipment intended for other services if they can do it while meeting strict spurious emission requirements (Part 97 may be the only service where this is still true). If you were to modify it for the 160m band (1800-2000 kHz) by reducing the inductance in the coils, you could run the full kilowatt in CW (Morse code), but you would have to lower the power to about 375 watts when running AM phone (since this will produce 1500 watts at peak modulation).

80m (3500-4000 kHz) has much more activity than 160, and propagates further out at night, but your transmitter would need more drastic surgery - new tuning circuits in every stage.

One possibility is that you could sell it to a licensed ham who wants to put it on the air. (Check current regs first, it's been awhile since I was on the bands).

It probably has a power cutback to either 250 or 500W...possibly both. I've worked on one of those McMartins a long time ago...not a bad rig. 160 conversion is EZ...80 not quite so but doable.

It might be fun to run it into dummy load. Looks like it's all there don't part it out tube rigs are getting rare. If it has power cutback it will reduce the power consumption, unwanted RF radiation and increase the tube life.

I'm betting there may well be a built-in dummy load...lots of 1kW AM rigs had them...usually a bunch of big resistors mounted up near the top of the cabinet & possibly some sort of switch/jumper arrangement to switch from antenna output to the dummy. Can't recall if the McMartin I worked on 30-odd years ago was so equipped.

Late to the party, but for potential buyers, how about state/local agencies, for traffic information stations? IIRC, there are two fixed frequencies in each operation area for such public service broadcasts - perhaps a locale with only one frequency used, and would like to add a second? Overkill, perhaps, but just a thought.

Or, Charlie, take it to sea and be a Pirate radio operator. 12 Miles out, say?? :)

Many hams are converting old tube AM broadcast transmitters for AM use on the 80 meter band. A Google search will bring up some information.

I never operated 160m when I had my OTA ham station in suburban Cleveland. The vertical and dipole antennas I used were not tunable to 160. Never used any kind of high power transmitter, either; the highest power I ever used was 100 watts, from my Icom IC-725. 160m does not apply to my current setup (Echolink), since it is not OTA ham radio but purely streaming audio over the Internet, with the capability to link to other stations and even control other stations remotely. I also operated 2 meters through local FM repeaters.

However, I did play with a 0.1-watt (100mW) AM transmitter (Lafayette Radio KT-195, three tubes, 2 50BM8s and a 36AM3 rectifier tube) in the early 1970s, putting a very small (!) AM radio station on the air for about a year and a half from my home town. I couldn't use any kind of outdoor antenna with it, so was restricted to the wire antenna which had been supplied with the kit; any kind of longer antenna would have caused the transmitter to put out some level of power over 100 mW. The transmitter put out a strong enough signal (!) with its supplied antenna, however, to be heard only about five hundred feet either side of my home; the best reception report I ever had with this super-peanut whistle was in the spring of 1971, when someone reported hearing the signal at the corner of my street, near the mailbox. Conditions must have been extremely good that day as I never received another reception report like that again, from then until the station signed off for the last time.

I had to give up the station when I moved in 1972 (long story), but it was a lot of fun while it lasted. My amateur radio station, WN8NHV, however, replaced it (I had received my Novice ticket shortly before I moved; got the station on the air 97 days later).....and the rest is history.

BTW, I would think using a 1-kW broadcast transmitter on 160 meters would be illegal, to say nothing of the fact that hardly anyone uses AM on any amateur band (except perhaps six meters) anymore. These transmitters were not intended to be used on the amateur bands; moreover, the modifications required to allow the transmitter to operate on 160 meters (or any other amateur band) would probably, even likely, void the transmitter's FCC approval, which would be valid only as long as the transmitter was operated within the AM broadcast band. I remember seeing a cartoon in one of the electronics magazines (Electronics Illustrated, long since defunct, comes to mind) in which an amateur was in a jail cell, talking to his cell mate. The amateur had been cited by the FCC for calling CQ on the AM broadcast band, over a 50-kW broadcast transmitter. I'll never know, but my best guess is the man lost his amateur license as well as having had to serve the prison sentence. There was also the story of a woman who was an announcer, on the night shift, at a traffic-information station on 530 kHz. The station was legal, but the woman got bored after several nights of announcing only traffic reports; she eventually started singing and playing records over the station, and was eventually fired for illegally playing music over a TIS radio station. The company or concern to which the station was licensed probably was cited as well.

Well, it hasn't moved anywhere. It still sits in the same place it did when I got it home a couple of years ago. It really needs to find a new home.

I was not aware that transmitters needed FCC approval to be used on ham bands. Sold specifically for ham band use, commerically, yes.

They just need to meet the requisite power and bandwidth rules.

As far as AM goes, I hear AM all the time on 80 and 40 meters,
and even on 160 meters at times.

A broadcast band transmitter of say 1 or 2 kW or less, if not specifically designed for only the lower parts of the band, should be easy to get to work around 1.9 MHz. It would be crystal controlled, of course, but any competant builder could build a tube or transistor buffer amp to take output from a synthesizer or VFO and use it to feed the nominal crystal oscillator.

If the transmitter did not have a built-in audio limiter with essential bandwidth filter, a simple external filter would satisfy the bandwidth requirment. If it did have that, the internal audio filter would need serious modification.

Somebody should take this transmitter and do it!

Homebrewing has always been a major part of the ham radio hobby. Anyone can make/modify and use their own TX and RX gear without the gear needing government certification as long the gear complies with relevant power limits for the frequency it is used on as well as other standards and the operator is ham with the proper license.

Unless someone wants to use it as an AM broadcast band rig in the future there's nothing wrong converting it to a ham band.

Well you could build/buy a shielded dummy load for it and use it as a overly complicated room heater. and if only 100mw of power leaks out, you could use it to broadcast to your vintage radio collection. Yeah ok that might be easier said than done.:worried:

It's perfectly legal to operate that transmitter on 160 meters as long as it's kept under the legal power limit and operated by a General class or above operator. There's plenty of hams who regularly run modified AM broadcast transmitters (they're actually pretty popular).