HFU HF Underground

Technical Topics => Part 15 AM and FM Station Operation => Topic started by: ThaDood on April 04, 2020, 0616 UTC

Title: Part #15 gear out there.
Post by: ThaDood on April 04, 2020, 0616 UTC
(Yeah, this was moved from RF Workbench.) Lots of home brew radiating gear, (For the 10ft FCC Part #5 compliant stuff.), but you have companies like, www.sstran.com , www.chezradio.com , www.am1000rangemaster.com , www.theradiosource.com , www.pll.gr , www.vectronics.com , www.iamradio.net , and there's others out there. Some companies even got-in on doing the 10ft Part #15 antenna like, www.isotronantennas.com , (Tell them that you want Part #15 compliant. Not cheap, but....) So, there's stuff out there. And, anything that's Carrier-Current, (Where you permissibly couple to the power lines.), from LPB, Inc., and Radio Systems, gets bought out almost immediately from ebay. So, somebody wants that gear.
Title: Re: Part #15 gear out there.
Post by: ChrisSmolinski on April 04, 2020, 1239 UTC
Talking House transmitters turn up at Goodwill now and then, I found three of them new in box last year.
Title: Re: Part #15 gear out there.
Post by: Σ on April 04, 2020, 1312 UTC
I'm looking for an inexpensive carrier coupler for a low power AM TX I have. Yes, they do get gobbled up on eBay quickly.

I run a whole house/yard FM TX that broadcasts anything I am listening to on my computer... including my KiwiSDR so I can listen remotely in the yard.
Title: Re: Part #15 gear out there.
Post by: ChrisSmolinski on April 04, 2020, 1651 UTC
I run a whole house/yard FM TX that broadcasts anything I am listening to on my computer... including my KiwiSDR so I can listen remotely in the yard.

I do something similar now and then, I use one of the inexpensive car FM transmitters designed to broadcast your iDevice audio into your car radio:

https://www.amazon.com/gp/product/B001AIM5ZE/ref=ppx_yo_dt_b_search_asin_title?tag=blackcatsyste-20

BTW these devices all use the same IC to do the transmitting. It's a neat chip, it has an I2C interface, you can actually override what the little uC in the dongle sends to it, and set your own frequency and other settings, and send RDS data as well.
Title: Re: Part #15 gear out there.
Post by: ThaDood on April 05, 2020, 0628 UTC
Oh boy... On a Carrier-Current Coupler, you may have to roll your own, since LPB and Radio Systems are gone. However, there are power line couplers for mining companies, (At least, there use to be.). That was the only way that they could send down a radiating signal into a mine shaft was to couple to the power lines going down there. With all of these mining companies going bye-bye, I'll bet one can be had. Ernest Wilson, formally of Panaxis Productions, had shown in is Carrier-Current books on how to build a coupler. Also, look for on-line .PDF books by James R. Cunningham for this to download. Basically, you are looking for a medium wave tuning network that let's you tune down to very low impedance, like 10 Ohms and less. Over 20 years ago, JTA gave me a Radio Systems TR-20 transmitter and a CP-15 coupler. The problem was, it looked like lightning directly hit it. The TR-20 was a total loss, with thumb sized burnt holes in both the PS and Finals boards, but the CP-15 Coupler was fixable, and I'm using that today. So, ya never know. 
Title: Re: Part #15 gear out there. RS CP-15 on ebay, 4/5/2020.
Post by: ThaDood on April 05, 2020, 1927 UTC
Here's a radio Systems CP-15 Carrier-Current Coupler on ebay now,   https://www.ebay.com/itm/RADIO-SYSTEMS-PHASE-II-CP-15-COUPLER-AM-RADIO-BROADCAST-TRANSMITTER/184186421837?hash=item2ae25dc24d:g:Vy0AAOSwr9ReVYyS
Title: Re: Part #15 gear out there.
Post by: JimIO on April 05, 2020, 2146 UTC
You could start with this to make one:

https://www.ebay.com/itm/DIY-Kit-QRP-manual-Antenna-Tuner-Tune-1-30Mhz-For-HAM-RADIO-CW/182607192047?epid=23005640968&hash=item2a843c9fef:g:O~AAAOSwgkRVT0hS

~
Title: Re: Part #15 gear out there.
Post by: ThaDood on April 06, 2020, 0527 UTC
Huh... Might be OK to Neutral-Inject in to the Neutral of the home AC power, but I certainly wouldn't couple that to the HOT. Heck, for the price, you can't beat it. And, since it's a kit form, most likely you can improve it to work much more efficiently on the AM BC band. That 1MHz limit is a bit FREQ limiting, since most Carrier-Current ops use the lower part of the band, since the lower FREQ's can ride the long power lines further. 
Title: Re: Part #15 gear out there.
Post by: JimIO on April 06, 2020, 1724 UTC
Just add a couple AC rated capacitors and fuses and you could feed both sides.

~
Title: Re: Part #15 gear out there.
Post by: JimIO on April 06, 2020, 1735 UTC
https://components101.com/capacitors/x-rated-or-dropping-capacitors

~
Title: Re: Part #15 gear out there.
Post by: Azimuth Coordinator on April 06, 2020, 1827 UTC
I have in the Rack a very Rare Broadcast Warehouse TX1  10mw  FM Exciter.. That is part 15 Compliant.. But depending on the Antenna..  you can easily exceed 250uv @ 3 meters.. My Singer NM 37/57  has it a 500uv @ 3 meters with a Circular Polarized Antenna.  It's been my main On Air for several years..  Range is around 1000 feet with good fm tuner around 200 feet with your average portable radio.   I started with a Ramsey FM100B which was pretty good for the price.  But then the next thing you know there's a PTEK FM25E in the rack... 

tAC
Title: Re: Part #15 gear out there.
Post by: Σ on April 06, 2020, 2026 UTC
I have a Drake FM-1000 CATV stereo modulator that I use for around the yard broadcasts. It has a crippled antenna so it stays within the confines of Part 15. Nice audio out of it.
Title: Re: Part #15 gear out there.
Post by: chanito on April 07, 2020, 2133 UTC
What I need is an accurate VHF QRP SWR/Wattmeter. I've been using a Diamond, but down to the 1 watt range I don't think it's very accurate. Need to be able to measure down to mw.
Title: Re: Part #15 gear out there.
Post by: secretlab on April 12, 2020, 1416 UTC
I recently bought a ChezRadio Procaster AM system out of Canada. This is the lower cost alternative to the US made Rangemaster. It includes a one-chip audio processor which is serviceable but not very loud. External processing may be used instead.

Having also owned a Rangemaster, I find the Procaster's coverage is less in either a strictly compliant 15.219 ground mount or a 10' elevated mount ('shielded' ground - center conductor of 7/8" Heliax to ground with shield grounded at bottom but open at the top). It does sound like a local within 1000' though, which was the goal. Build quality of the Procaster is very good. Audio quality is OK. Gerry of Chezradio was helpful with a minor issue but seemed unwilling to discuss technical aspects of his proprietary system.

in an elevated installation, what constitutes a suitable RF ground point is in the judgment of any FCC agent who may come to inspect your transmitter. A certain FCC NOUO (Notice of Unlicensed Operation) has seemed to indicate that a 'shielded' lead or path to ground may be acceptible. Here's the underlying rule:

15.219 Operation in the band 510-1705 kHz.
(a) The total input power to the final radio frequency stage (exclusive of filament or heater power) shall not exceed 100 milliwatts.

(b) The total length of the transmission line, antenna and ground lead (if used) shall not exceed 3 meters.
Title: Re: Part #15 gear out there.
Post by: Josh on April 12, 2020, 2144 UTC
(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"
Title: Re: Part #15 gear out there.
Post by: ChrisSmolinski on April 12, 2020, 2325 UTC
(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.
Title: Re: Part #15 gear out there.
Post by: JimIO on April 13, 2020, 0033 UTC
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.

~




Title: Re: Part #15 gear out there.
Post by: secretlab on April 13, 2020, 0207 UTC
(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.
Title: Re: Part #15 gear out there.
Post by: ChrisSmolinski on April 13, 2020, 1601 UTC
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.
Title: Re: Part #15 gear out there.
Post by: Dave Richards on April 14, 2020, 0218 UTC
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.
Title: Re: Part #15 gear out there.
Post by: ChrisSmolinski on April 14, 2020, 1257 UTC
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.
Title: Re: Part #15 gear out there.
Post by: Pigmeat on April 14, 2020, 1549 UTC
(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.
Title: Re: Part #15 gear out there.
Post by: chanito on April 30, 2020, 1655 UTC
Rooting around in the attic and found my box of BA-1404 experimentation from 1991.


(https://i.imgur.com/pAHOIBb.jpg)










Title: Re: Part #15 gear out there.
Post by: ThaDood on May 01, 2020, 2249 UTC
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.
Title: Re: Part #15 gear out there.
Post by: chanito on May 15, 2020, 2042 UTC
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.
Too bad there's not a MW version.
Title: Re: Part #15 gear out there.
Post by: Dave Richards on May 16, 2020, 0501 UTC
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 (https://www.6v6.co.uk/vcomp/pages/spitfire.htm)
Title: Re: Part #15 gear out there.
Post by: Kingbear Radio on July 23, 2020, 1657 UTC
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.