This early "Talking House" transmitter is not at all like the one that has been so frequently discussed here. It doesn't have the automatic, motorized tuning that is covered in patent 6,973,294, filed on 08/23/2001 and issued on 12/06/2005.
If you search https://apps.fcc.gov/oetcf/eas/reports/GenericSearch.cfm for Applicant name: Radio Systems Design, Inc., you will find 3 different FCC IDs issued. That's 3 different units going back to 1984. The latest one, dated 09/04/1997 is the one covered by the patent.
Yeah the OP's unit is probably the first or second run model using the ISD 90 second recording chip. The cassette models did not have the auto tuner in them either.
If you look at the photos provided by the OP and the patent diagrams you can see that matching is done with a common LC tuned circuit and a variable cap connected to the same gearing as the variable cap that tunes the frequency of operation. Not exactly a great approach but it worked.
RFB
You guys have motivated me to get into part15...right here in SWMO...I am starting with that Talking House transmitter and a long (short) antenna with a short (long) coil. I am thinking right in the middle of the band at 1000 KHz, mainly because I dug up a simple circuit that will make the AM transmitter simple with use of a crystal oscillator (which I have) at 1.0 MHz...I'm gonna program the stuff from my music collection, along with some feeds (live and pre-recorded) from the FTA satellite system that I have...all being taped on a...wait for it...VCR! Yeah, I got the idea years ago when they became obsolete and someone gave me 20 brand new never opened VCR Hi-Fi tapes. As you know, video quality stinks after several plays, but the audio is virtually un-matchable...when I get the set set-up, I will attach new pics of the "studio/station." Wish me luck, I'm going to need it...
Dave VQX
Back when VCRs were standard, I heard of radio stations using especially S-VHS hi-fi tracks for 2-hour long radio program origination, storage and air-checking.
JVC came out with recorders that made conventional VHS tapes record in the S-VHS mode.
Everything seemed heaven bound until overnight, the VCR became dead-weight.
I still have too many VCRs from the AV production & duplication business we ran. Enough dead-weight to anchor a ship.
I know I could do better quality and less space with digital (except that hard-drive space can get expensive), but I prefer to do things re-using items that would otherwise go to the landfill...I regularly visit my local thrift stores (where the revenue goes to the blind and the vets) and buy what seems to be a never-ending supply of small project boxes that used to be data switches and the like...they are really heavy duty, feature heavy click type rotary switches, rubber feet and easy-to open cabinet tops...all for less than $2 a piece...along with extension cords from garage sales that have seen better days now a coil or wire antenna...my grandparents lived during The Great Depression and taught me to re-use and use over and over and over...
Dave VQX
since you hare going to void the certification by adding a live line to the the talking house might as well make a pll circuit for it while you are at it and do away with that l/c vfo crap. just be prepared since it will be modded that if/when a visit should occur it will be on you to prove that the final rf input is still 100mW and a 3m antenna including ground and coax. it will get a little more scrutiny being it's modified than it would being a stock certified unit.
I've been reading the FCC "NOU" files and I've noted VERY FEW if ANY AM radio violations recently...it seems they target the BLATANT FM not-so-micro broadcasters...is this everyone's perception? I mean, I want to operate within the law, but will they even care if I'm accidently on the fringe?
Dave VQX
that seems to be the case for now. we saw an uptick in am violations few years back but has seemed to calm down in recent years but one thing that is known is that the FCC often checks the various part 15 forums and it is assumed that they have found violators using that method.
You'd think that "leave well enough alone" would suffice unless there's a complaint...I'd hate to be that bored...thanks!
well we know by site logs that they read part 15 forums. we know a few p15 am'er from Radio Info community radio forum have been cited for long ground lead and/or excessive input power.
I guess I'll go with my original plan and do it by the book...
hardly concrete proof but better safe than sorry i say.
once a member here. He signed up in order to answer a question posed by one of our members. Unfortunately, on the day he registered we had a site crash and his logon didn't work. I contacted him by email and invited him to re-up but he declined.
Point being, the FCC did and probably still does visit this forum. It would be really great if a representative would sign up and post.
I'm going to go for now and build the antenna/enclosure for the transmitter...later!
they probably would but like any enforcement agency there is legality reason why they can't.
i'm sure a lot of the agents at the fcc would like to see changes to the rules for the better and to interact and answer enforcement questions as well.