Yes, Radio8z, I've wondered if perhaps a particular FCC agent might openly join in, namely one who just happened to find part 15 radio worth talking about.
I've also wished for a generous attorney with both FCC law and copyright law as his/her specialty.
We have a terrific number of real world RF engineers, so we did get one big break.
"the FCC did and probably still does visit this forum. It would be really great if a representative would sign up and post."
They may be around more than we think! 😉
RFB
The FCC field inspectors I've heard described by those who actually encountered them is that they are serious, mature, reasonable people, not the rogue cop types we read about so often with their tazers and pepper spray. If the image of mature professional is the correct one, perhaps the inspectors don't fiddle with mickey mouse tiny radio when there is a whole spectrum universe loaded with massive power levels and serious purposes.
After all, we hear that they are called to action by complaints, which suggests they are not actually looking for miniscule violations.
"we hear that they are called to action by complaints, which suggests they are not actually looking for miniscule violations."
Not entirely true. If a field agent happens to stumble upon an unauthorized signal while inspecting something else, then they do the direction finding, measuring and determine at that point if a field
issued NOUO is warranted, fill out their report and hand that in once back at home office, or fax it if they have to be elsewhere, or even email their reports to home office.
They may not be hunting, but they are vigilant.
RFB
I took the timer board out, but it still wants to only record to the digital "storage" and then play it back...is there anyway to get it to just play (in real time) what I want directly to the transmitter? My Ramsey AM1 is not oscillating much (even with the 880 KHz crystal) and my AM25 is not here/assembled yet...does the 4 position (PLAY, ???, ???, RECORD) switch have anything to do with this function? I have no owners/instruction manual available and have not been able to find one...any help???
I think you're throwing good time, money and effort against bad here (even if you get it working, it's not going to sound all that great). I know for a fact that the newer Talking Houses will broadcast 'live', either via switch or automatically when a signal is present (depends on the model, the switch is older). These are the ones that look like hi-fi components. You can pick one up on e-bay easily for under $50, and sometimes a lot less than that.
Plus, you have some expansion capability. If you can find an ATU (not many out there, though), you'll get a lot more range than with the wire antenna.
You're right, but I can't let a piece of (s) plastic beat me...I know that there has to be a way, plus it gives me something to complain about until the Ramsey arrives...just curious how stuff works. Thanks!
Hi Mr. amradioman!
From your post, it seems to
me that you have a Ramsey AM-25
on order.
I understand the AM-25
can be a great transmitter.
I do not have one myself, but I
have read that the transmitter
needs some modifications to work
correctly. I do not know what they
are, but you might want to check into
that.
As you might have read, I am using a
1971 LPB RC-6A for my carrier current experiments. I have an SS-Tran AMT-3000
for my "outside over the air" set-up, but
that is not running now.
The RC-6A is a vacuum tube rig and seems to
be doing pretty well. But I would love to
have an AM-25 as a back up. Because...
I think some people have AM-25s for
CC set-ups - I believe I have heard that.
Others are using them for Part 15.219
operation, i.e., 3 meter stick and 100 mW
DC in.
Anyway, the AM-25 is a good rig. But
I think it needs mods to realize it's
potential.
I wish I knew more about this.
Best Wishes,
Bruce, "W-60-HZ" 1020 kHz Carrier Current
amradioman,
It appears you have an AM-25 on order. I predict you will like this transmitter and it lends itself to modifications. I have found that the AM-25 will drive almost any antenna but best results are obtained by using a resonant base coil loaded antenna.
My advice is to build the AM-25 "stock" according to the instructions, check it out, and get to know it. Then if you are so inclined consider some modifications.
If built "stock" and adjusted according to the manual the AM-25 will deliver 141 mW OUTPUT RF Power to a 30 ohm resistive load (in the range of load R for a resonant base coil antenna with a good ground). That's the good news. The bad news (depending on one's perspective) is that the final DC input power is 469 mW and the efficiency is 30%. This exceeds the input power limit of 100 mW according to Part 15.219. This also causes Q9 to run hot enough to discolor the PC board. If you consider these as problems then there are modifications that can be made.
Here's a link to modifications which can bring the AM-25 into compliance with the 100 mW limit and increase the efficiency from 30% to the 70-80% range. If you replace the T44-15 cores with T50-2 toroids (wound with 50 turns for the high end of the band and using the capacitors shown in the modification articles) the efficiency increases to 82% with all the mods in place giving 82mW RF output power for 100 mW DC final input power.
I am not trying to persuade you to do the mods rather I just want you to be aware of the options. You may decide they are more trouble than they are worth and I did them primarily to learn and to push the technology for high efficiency.
In any case, let us know how you like the AM-25.
Neil
i would scrap that talking house from the 80's for parts get a THII off ebay, not a iAM (there is some question of illegal mods done by the company on the iAM), but THII or an AM25 with neals mods done.
that original TH is just not worth the time for what you will get out of it.
On the AM 25, on the foil side is a foil trace that runs right underneath the coupling transformer between the oscillator/pll section and final. I used a short piece of small coax to shield that path from being saturated by the high level signal above it on the component side.
Just doing that improved things a whole lot. Add Neil's mods or other mods found on the web will do that unit some justice.
RFB
There's illegal mods for my certified iAM transmitter?
Keep in mind Part 15 equipment doesnt need to be type accepted and such modifications shouldn't effect the end user. (unless it puts the transmitter in question out of compliance)
Though to be totally honest,
I cant really tell the difference between my high dollar iAM and the TH4 I got for $90 on Ebay.
Those so-called mods are not illegal until the FCC says they are. If your Talking House has an FCC certification ID, then it's certified, until the FCC states otherwise. Don't let speculation from others worry you.
Apparently the I AM manufacturer made improvements to the Talking House model. As the story goes, the audio and modulator sections were modified and the I AM marketed under the original Talking House certification.
That info was posted here sometime ago during the ATU wars. I don't know that it was substantiated.
What was the last model before iAM took over the TH Transmitter?
Mine in current use every day is, AFAIK, the v5 model. It reproduces good tone quality, provided the signal has correctly applied multi-band EQ, multi-band compression, and peak limiting. I got it on eBay for $50.
I have another which looks exactly the same, but its sound is not as good. Once again, I think this has more to do with parts used in batches. IOW, the mfrs are going with the best parts prices they can get, and that very likely means differences in tolerances, perhaps even different values that will allow the unit to still work within its target user group ...
... which may not be "us", because our expectations, especially for b'casting music, is likely higher than a lot of users.