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Author Topic: Spitfire Am transmitter  (Read 1971 times)

Offline chanito

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Spitfire Am transmitter
« on: February 13, 2020, 0204 UTC »
Anyone have this gear? Comments? Thinking of putting one on to cover my property with lovely AM-ness.
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Offline redhat

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Re: Spitfire Am transmitter
« Reply #1 on: February 13, 2020, 0455 UTC »
Looks a lot like the mosquito.  I had to fix one for someone recently.  Not much to it, commonly available parts, seems to do the job.

+-RH
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Offline Stretchyman

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Re: Spitfire Am transmitter
« Reply #2 on: February 13, 2020, 0557 UTC »
Waste of time, buy something decent.

From me!

 ;)
'It's better to give than receive' so why RX when you can TX!

                            Buy one from me, NOW!

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                                              ;)

Offline redhat

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Re: Spitfire Am transmitter
« Reply #3 on: February 13, 2020, 0614 UTC »
Waste of time, buy something decent.

From me!

 ;)

Your transmitters are not legal for part 15 transmission in this country.

+-RH
Somewhere under the stars...
WinRadio Excalibur/305 w/ a chi-town resonant loop, Kenwood KDC-U356 for mobile listening.
Please send QSL's and reception reports to xfmshortwave [at] gmail [d0t] com

Offline Stretchyman

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Re: Spitfire Am transmitter
« Reply #4 on: February 13, 2020, 1008 UTC »
Who cares...

+ They transmit more than 10'!

Str.
'It's better to give than receive' so why RX when you can TX!

                            Buy one from me, NOW!

Great discounts on ALL my transmitters if purchased via HFUnderground


                                              ;)

Offline redhat

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Re: Spitfire Am transmitter
« Reply #5 on: February 13, 2020, 1817 UTC »
Under part 15 rules, AM coverage is up to a mile depending on the installation and so forth.  The OP mentioned he was interested in covering his property only, not the county.  Also keep in mind the US government recently enacted tougher legislation against AM and FM band pirates, with fines up to $2M.  How they plan on enforcing that I don't know, but the point still stands.

+-RH
Somewhere under the stars...
WinRadio Excalibur/305 w/ a chi-town resonant loop, Kenwood KDC-U356 for mobile listening.
Please send QSL's and reception reports to xfmshortwave [at] gmail [d0t] com

Offline Brian

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Re: Spitfire Am transmitter
« Reply #6 on: February 13, 2020, 1900 UTC »
Do part 15 transmitters need to be of an approved make or can you use any type providing it conforms?

Offline redhat

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Re: Spitfire Am transmitter
« Reply #7 on: February 13, 2020, 1906 UTC »
You are allowed to build your own equipment.  If the commission comes out, they will measure your field strength to confirm it falls within the limits.  They do have some arcane rules which are not real clear, probably to allow more latitude on the part of the inspector.

+-RH
Somewhere under the stars...
WinRadio Excalibur/305 w/ a chi-town resonant loop, Kenwood KDC-U356 for mobile listening.
Please send QSL's and reception reports to xfmshortwave [at] gmail [d0t] com

Offline ChrisSmolinski

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Re: Spitfire Am transmitter
« Reply #8 on: February 13, 2020, 1934 UTC »
You are allowed to build your own equipment.  If the commission comes out, they will measure your field strength to confirm it falls within the limits.  They do have some arcane rules which are not real clear, probably to allow more latitude on the part of the inspector.

+-RH

Elsewhere there was a rather lengthy and amusing thread regarding the ground wire and whether it counts as part of the antenna. From a literal reading of the pertinent FCC regs, it does:

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.

(c) All emissions below 510 kHz or above 1705 kHz shall be attenuated at least 20 dB below the level of the unmodulated carrier. Determination of compliance with the 20 dB attenuation specification may be based on measurements at the intentional radiator's antenna output terminal unless the intentional radiator uses a permanently attached antenna, in which case compliance shall be demonstrated by measuring the radiated emissions.


Yet the Talking House transmitter, which is certified as Part 15 compliant, has a ground connection via the DC power cord, which then connects to your house wiring. Which most certainly does radiate and effectively work as an antenna. In fact in one case the FCC brought this up during an inspection, the TH transmitter in question was in an apartment building and all the wiring was acting as an antenna. This is probably how some ops are able to get a mile range.  The FCC itself mentions 200 ft as a typical range for Part 15. While this is not in the official rules, I suspect they use this as a rough guide, and if your range is significantly more, they will not be happy
Chris Smolinski
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Offline chanito

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Re: Spitfire Am transmitter
« Reply #9 on: February 14, 2020, 0202 UTC »
If I felt I could get away with it, I would put in a Stretchyman xmtr, hands down. Unfortunately, I can't take chances of retribution from local licensed stations who will invariably feel offended by the production quality of my station compared to theirs :-)


Got to stay with the 100mw and 9' antenna. I will probably take a whack at doing the SSTRAN antenna system and mount the xmtr on the pole to comply with Part 15.
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Offline ThaDood

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Re: Spitfire Am transmitter
« Reply #10 on: February 15, 2020, 1917 UTC »
You can go the other option of AM Carrier-Current Coupling, like some college stations still do. Most ops tend to stay away from that method, since coupling to power lines tend to scare away folks. Some ops are running like 30W into the lines, while others are 5W, or less. I turned mine down to the TX's MIN of 200mW carrier, since more transformers have been installed on my road. Today, it doesn't matter if I run 10W, or 100mW, Carrier-Current, since the power transformers are a brickwall RF stop. And, I'm Neutral Injecting the James R. Cunningham way. https://sites.google.com/site/lowpowerradio/home/low-power-broadcasting-by-james-r-cunningham   Still, some ops are getting out a few miles doing Carrier-Current, and it's totally Part #15 permissible still. 
I can't decide upon what's worst, young and stupid, or old and chemically dumbed down.

Offline chanito

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Re: Spitfire Am transmitter
« Reply #11 on: February 16, 2020, 1919 UTC »
It is interesting the TH is allowed to use a TH range extender connected via coax, supposedly legally.
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Offline chanito

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Re: Spitfire Am transmitter
« Reply #12 on: February 20, 2020, 1921 UTC »
And, I wonder if the 3m rule applies to actual wire length or if a loaded coil with a radiator in excess of 3m of wire wound, but not in physical "length", would be in compliance.
PCR-1000, PCR-1500, RSP1A, RSP1, VR-120D, HDT-1, Accurian HD, Royal 3000
Caras HF-315, Belar LP-1A, SuperAntenna MP-1, RatShack 20-043 discone, MLA-30, 100' wire

Offline Josh

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Re: Spitfire Am transmitter
« Reply #13 on: February 20, 2020, 1944 UTC »
And, I wonder if the 3m rule applies to actual wire length or if a loaded coil with a radiator in excess of 3m of wire wound, but not in physical "length", would be in compliance.

Was thinking the same thing, you can put a lot of wire in a 3m space.
We do not encourage any radio operations contrary to regulations.

Offline ChrisSmolinski

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Re: Spitfire Am transmitter
« Reply #14 on: February 20, 2020, 2050 UTC »
And, I wonder if the 3m rule applies to actual wire length or if a loaded coil with a radiator in excess of 3m of wire wound, but not in physical "length", would be in compliance.

Was thinking the same thing, you can put a lot of wire in a 3m space.

Loading coils seem to be allowed, but you better make sure it's not really an antenna in disguise.

http://diymedia.net/old/stuff/lpamhandbook.pdf
Chris Smolinski
Westminster, MD
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netSDR / AFE822x / AirSpy HF+ / KiwiSDR / 900 ft Horz skyloop / 500 ft NE beverage / 250 ft V Beam / 58 ft T2FD / 120 ft T2FD / 300 ft south beverage / 43m, 20m, 10m  dipoles / Crossed Parallel Loop / Discone in a tree