Part #15 gear out there.

[ChrisSmolinski]

(b) The total length of the transmission line, antenna and ground lead (if used) shall not exceed 3 meters.


"that's no 50ft ground lead, that's the dc return to the psu"

This is actually an issue with many Part 15 transmitters, even those FCC Certified such as the Talking House transmitter. There is significant radiation via the ground wire on the power cable which then gets coupled to the building wiring where it radiates.

[JimIO]

I found an "original" Talking House on ebay. ~$20 + $10 shipping.
I'm beginning to think it was a mistake. When I got it I unboxed it on
the kitchen counter and plugged it in. The ground fault breaker tripped.
I got the DMM and checked from the line to nutral of the plug and got ~120
ohms. I checked line/nutral to the ground pin and it is open.
I took the 4 scews out of the bottom. The bottom comes off and everything
is mounted to the top. It appears to have a shielded
3 wire power cord. Black + White +Green + uninsulated braid.
There is a small power transformer. Black and White are each connected
to one transformer lead. Green and braid are connected to the transformer
frame. There ts a wire from the transformer frame to one of the circuit
boards. There is a wire from nutral to the same board.
I plugged it into a non ground fault outlet and it powers up.
Apparently there is cicuitry to prevent it from working if it is not
plugged into a grounded outlet. I looked around the net and could
not find anything so it's just sitting in a pile for now.

~

[secretlab]

(b) The total length of the transmission line, antenna and ground lead (if used) shall not exceed 3 meters.


"that's no 50ft ground lead, that's the dc return to the psu"

This is actually an issue with many Part 15 transmitters, even those FCC Certified such as the Talking House transmitter. There is significant radiation via the ground wire on the power cable which then gets coupled to the building wiring where it radiates.

Rangemaster sells a ferrite, usually used for the ground lead, which I believe the FCC cites as ineffective in another NOUO. Presumably, connecting leads to the PSU were present and part of the certification in the Rangemaster, Procaster, and Talking House units.

BTW, I decided to elevate 10' due to trespass and vandalism issues with a neighbor's kids. It seems to lead to no improvement in coverage over a ground mount.

[ChrisSmolinski]

IIRC there was one FCC inspection (I do not recall if it resulted in a NAL/NOUO) where the agent determined that the TH transmitter was radiating via the electrical wiring in an apartment building.

[Dave Richards]

IIRC there was one FCC inspection (I do not recall if it resulted in a NAL/NOUO) where the agent determined that the TH transmitter was radiating via the electrical wiring in an apartment building.

I remember a discussion of that online too. The TH was confiscated, though I don't recall if it resulted in a NOUO either.

The ground lead issue is quite a perplexing one - especially when some certified transmitters, by their very design, seem to encourage the violation of this rule. My interpretation is that if you want an installation that strictly follows the letter of the law, and would be highly unlikely to fail an inspection, then you mount your transmitter at ground level, with a very short lead to the ground connection. Any type of elevated installation may not have outsize range, and may conform to the spirit of the law, but you will be more likely to be at the mercy of the opinion and outlook of the visiting Field Agent - if you have an inspection.

[ChrisSmolinski]

IIRC there was one FCC inspection (I do not recall if it resulted in a NAL/NOUO) where the agent determined that the TH transmitter was radiating via the electrical wiring in an apartment building.

I remember a discussion of that online too. The TH was confiscated, though I don't recall if it resulted in a NOUO either.

The ground lead issue is quite a perplexing one - especially when some certified transmitters, by their very design, seem to encourage the violation of this rule. My interpretation is that if you want an installation that strictly follows the letter of the law, and would be highly unlikely to fail an inspection, then you mount your transmitter at ground level, with a very short lead to the ground connection. Any type of elevated installation may not have outsize range, and may conform to the spirit of the law, but you will be more likely to be at the mercy of the opinion and outlook of the visiting Field Agent - if you have an inspection.

Yes, I was thinking the same thing. I guess one of the most strict implementations possible would be a ground mounted transmitter using a battery, so no possibility of extra wires radiating. Perhaps with a solar panel for charging the battery.

Another question that often comes up is the use of loading coils, and whether they "count" as antenna length. As with all of this, it depends on the agents interpretation of the actual implementation. What one agent would pass as compliant another might decide is in violation of Part 15.

[Pigmeat]

(b) The total length of the transmission line, antenna and ground lead (if used) shall not exceed 3 meters.


"that's no 50ft ground lead, that's the dc return to the psu"

This is actually an issue with many Part 15 transmitters, even those FCC Certified such as the Talking House transmitter. There is significant radiation via the ground wire on the power cable which then gets coupled to the building wiring where it radiates.

Rangemaster sells a ferrite, usually used for the ground lead, which I believe the FCC cites as ineffective in another NOUO. Presumably, connecting leads to the PSU were present and part of the certification in the Rangemaster, Procaster, and Talking House units.

BTW, I decided to elevate 10' due to trespass and vandalism issues with a neighbor's kids. It seems to lead to no improvement in coverage over a ground mount.

LOL! The neighborhood kids used one of my longwires as the 'net' for their volleyball games. It was years before my wife told me what they up to.

[chanito]

Rooting around in the attic and found my box of BA-1404 experimentation from 1991.

[ThaDood]

For anyone wanting to do the AM Carrier-Current thang, here's a Radio Systems CP-15 Coupler,     https://www.ebay.com/itm/RADIO-SYSTEMS-PHASE-II-CP-15-COUPLER-AM-RADIO-BROADCAST-TRANSMITTER/143587226054 The One I have is from 1979, so this one might be newer.

[chanito]

Got the Vast V-FMT212R on the way to replace the Ramsey FM-25Aand allow me to play with RDS/RBDS, fingers crossed... Is USB powered and power adjustable through the control software from 0-200mw. Will pass the audio from RadioDJ to StereoTool to Vast using VB Cable via USB so all audio remains in the digital domain from player to transmitter. Should be interesting.


Update:  Got it last night. This thing is pretty trick.

• has integrated antenna matcher
• very quiet when idle. No pesky hum problems like the Ramsey xmtrs
• Has has a minimal audio compressor/limiter (not using)
• RDS was easy to set up. Picks up the song data from RadioDJ.
• has web interface for controls

Too bad there's not a MW version.

[Dave Richards]

I was sad to see SSTRAN stop selling their AMT3000 transmitter kit. To my mind, it was a great option for someone wanting to get their feet wet in Part 15, or for anyone not wanting to spend the kind of money that a Procaster or Rangemaster cost. Although the onboard audio processing was a simple one-band affair, it actually did a pretty good job on most audio signals. All this for a little more than $100. The closest thing to one of these that is still available, is the fully-built Spitfire, out of the UK, for about the same price as the SSTRAN. The Spitfire doesn't have onboard processing, though that would free you up to provide your own, if you want something a little more sophisticated than the single-chip solution provided by SSTRAN and Procaster. (The Procaster uses the same chip as the SSTRAN did).

I'm tempted to buy one of these Spitfires, just to have it. I regret ever selling my AMT3000, and wouldn't mind having a Spitfire on hand. I just know that if I don't buy one, one day, I'll wish I had.  However, my other hobby pursuits are currently taking up all my spare cash.

https://www.6v6.co.uk/vcomp/pages/spitfire.htm

[Kingbear Radio]

Interesting discussion! I've wondered about adding radials and ground wires, it seems if you mount the antenna at any decent height, you'd want to have the proper straight direct ground for surges and lightning to take the most direct path to ground. Maybe a lightning gap would work, like TV antenna lightning arresters had. What about a small version of a ball gap as AM broadcasters would use?

It seems fewer tech people would care about AM radio nowadays and if someone had a little more range. Would the FCC bother coming to your city to bother a part15 station that had a little more range? You would hear about local students getting in trouble for their phono kit they put a long wire on in the old days when everyone listened to AM radio, but now the vital services are wifi and 5G, not even FM it seems.