As I mentioned in another thread recently, faced with the fact that the SSTRAN AMT3000 kit has not been available for some years now, and used ones hardly ever appear for sale online, I decided to gather all the parts and build one myself from scratch, using schematics I found online.
I've attached a couple of pictures here. There are more pictures, and a full write-up on my blog at -
https://aa7ee.wordpress.com/2024/12/23/micropower-am-broadcasting-a-scratch-built-sstran-amt3000/
That's amazing. What kind of circuit board was that built on? How difficult was it to get the parts?
Thank you. It's a piece of 0.06" thick copper-clad @mark - the type people use to etch their own PCB's. I buy mine from a seller on eBay called abcfab. The parts are all readily available. There's nothing obscure, obsolete, or otherwise hard to get hold of. The only difference between when the AMT3000 kit was available and now, is that in the kit, the IC's were through-hole parts, with the exception of the SSM2166A audio processor chip. Nowadays, the through-hole IC's used in the kit are mostly obsolete, so I used SMD versions.
I'm not thrilled with the audio processing. It's OK, but it's not great. If and when I feel inspired, I would like to bypass that chip, and feed the transmitter with processed audio from my SW200, to see how the transmitted audio sounds then. Being a bit of a builder, I'm glad that I'm allowed to do this and stay on the right side of the law in the US, though I wish we had the slightly more generous allowances on FM that the Canadians do. But of course, I wish we were allowed a watt or two on AM into a much longer antenna, and 1 watt on FM. You always want just a little bit more than what you currently have........!
Wow,;that looks absolutely incredible. Much more attractive than the original. What did all the parts needed run you?
@rugster Oh wow! Your building skills (Rugster) are top drawer! What a fine looking piece of equipment!
Your wish list for better field strength allowances from 'Big Daddy FCC' bring a question to mind: based on the fact that the present Rules differentiate between 'home built' and 'kits', which category does that put your device in?
@carl-blare I think this would be in the home built category. It is strictly built from scratch by the individual and not from a "marketed" kit. The FCC has this advantage over Canadian rules which don't have any provision for kits of any kind, homebuilt whatever. Even operating legally.
Wow,;that looks absolutely incredible. Much more attractive than the original. What did all the parts needed run you?
Thanks @richpowers! Hard to say what the parts cost. I already had some of them. For the ones I had to purchase, I bought extras, to have some on hand for future projects (I often do that, to build up my stock of parts). If I added up the cost, it would probably be close to what the original kit cost, though that's just a guess.
@rugster Oh wow! Your building skills (Rugster) are top drawer! What a fine looking piece of equipment!
Your wish list for better field strength allowances from 'Big Daddy FCC' bring a question to mind: based on the fact that the present Rules differentiate between 'home built' and 'kits', which category does that put your device in?
Thanks @carl! Do the FCC Part 15 rules differentiate between homebuilt and kit? I thought the main differentiation was between certified transmitters and non-certified ones. We are allowed to build and operate up to 5 transmitters that are not certified. For people and organizations that are engaged in designing and building Part 15 transmitters for sale, they can be granted an experimental license that allows them to build and operate more than 5 transmitters.
The key phrase here is "build and operate". It is not illegal to build or own a transmitter for any frequency; it is the operating it that is regulated. I guess this part of the ruling basically means that you cannot have more than 5 homebuilt transmitters on the air at any one time.
@rugster Yes, there is a differentiation in the Rules between 'home-built' and 'kits'. Look at 15.23 about 'Home Built'... "Equipment authorization not required for devices that are ... not constructed from a kit... ";
The very next rule, 15.25 'Kits', does not refer to 'Intentional Radiators', so where else does it say anything about kits?
The answer is found in 15.3 Definitions (p) Kit, which is the only wording that implies that transmitter kits are legal.
I see what you mean @carl.
As for transmitter kits being legal, any transmitter that conforms to the relevant Part 15 regulations is legal, regardless of whether it is home designed and built, built from a kit, or purchased ready assembled and certified. Conversely, even a certified transmitter is illegal if it is not operated in accordance with the regulations. A Rangemaster with a very long antenna or ground lead, for example.
@rugster Yes, there is a differentiation in the Rules between 'home-built' and 'kits'. Look at 15.23 about 'Home Built'... "Equipment authorization not required for devices that are ... not constructed from a kit... ";
The very next rule, 15.25 'Kits', does not refer to 'Intentional Radiators', so where else does it say anything about kits?
The answer is found in 15.3 Definitions (p) Kit, which is the only wording that implies that transmitter kits are legal.
Something doesn't sound right Carl. Not sure what it is.
Apologies for my reply not being more detailed or accommodating @carl, but I'm on my way out to meet a friend. Happy Holidays!
@richardpowers - Richard Powers said "Something doesn't sound right Carl. Not sure what it is."
My guess would be that the thing that "doesn't sound right' is the disjointed, mis-matching, un-uniform, disorganized arrangement of the FCC rules as a confusing maze. What I write is merely my best effort to make sense out of the jumble. I believe the rules were assembled bit by bit by FCC legal writers and attorneys each separately compiling a portion of the rules.
A myth I like to refer to is the common belief held by part 15 hobbyists that so-called 'Certification' is some kind of a safe-harbor, even a requirement, but this indicates a lack of understanding of the simple thing Certification is intended to do, which is to make it legal to manufacture and market fully made transmitters - Period. It is not intended to bestow any rights to the end user. But, like the '200-foot' myth, FCC agents take the easy road by suggesting use of certified transmitters as a 'safe bet' rather than trying to explain the intricacies of the actual rules.
Of course you may come up with a different explanation.
@carl-blare I'm going to attack it later. Right now, all I can think about is how this could be some kind of an OTR episode...
+@richardpowers Ha, Ha, Ha! I can't stop laughing!