When topics drift we should have a calculator to determine how far off-topic it is.
Right now we are 4-degrees off-topic.
Hi Everyone .
I am sorry we are off of the original subject of the Ramsey FM100B,and this is one
reasin why I wanted to make sure I had a meter to put this transmitter in compliance.
Then the FCC gives me a statement that I cannot use the Ramsey transmitter.
Well you can see how I felt about it since that a $270.00 transmitter and then I paid extra to get it here fast. which made my total around $305.00 for this transmitter.
Then the extra time I took to make sure the solder connections were perfect. I solder
under a magnifying glass to make sure every connection was correct.
So when the FCC said that the kit was not in compliance and needed to have an FCC ID
number on the transmitter and kits with out it were not legal and building a home made
transmitter you design yourself is in compliance over the kits. Wow . I know there
is a part 15 rule that states this and I will find my folder with this in it. So the rule was
there and I did ask them. Why is Ramsey able to sell these then if you call them illegal
devices ? They said it was not illegal to sell them it the opperation of them that is illegal.
Anyways I wish it would be more clear stated but I was able to find where the company
had to submitt 2 of the kits to the FCC before marketting and it had to be where the
person constructing could not change the output power with adjustments.
I will find the folder and the rule and give it up here or type the rule so everyone can read
it.
now the meter I bought this from the Local FM radio statio since they bought more updated
meters.
Here is the meter. FCC told me to hook a quarter wave ground plabe antenna cut to the frequency I am transmitting on to the meter, They did give the ok on this meter.
Sadelco All Band Field-Strength Meter Model 719E
- metered output measured in db and mv ( sensitivity of meter is down to 10uv)
- audio output for channel ID
- are AC/DC with 115 VAC to 28 VDC x-former
-
- receives 54 to 216 mhz and 470 to 806 mhz
- will work most public service bands
- heavy-duty carry case with handle
-
- can use rechargeable NI-CAD batteries
This meter was ok by the FCC for checking power levels.
I am sure they can still be purchased,this one was calibrated for the local FM
station in Texarkana ,TX. They also had a spare and I bought it also.
Thanks
Hi Every one
I am guessing since the meter will read with very good accuracy they said it
was a good one to use.
I am going to try it at 3 meters from the transmitter with a quarterwave
ground plane antenna hooked to the meter. This is what the FCC told me to do to
make measurements. They said this was a very good meter and they originally
sold for $1500 each.
I paid around $600 each for them.
Thanks
Just thinking about your lucky purchase of FCC approved meters to measure the field strength of your FM transmitter, I got the idea that with two meters you can make two tests.
Do a field measurement with one meter, then do a field measurement with the other meter, and compare the two results. If all is well, they will be the same.
But could both of them still be inaccurate?
But could both of them still be inaccurate?
Hi everyone sorry
I had it lock up with my retirement papers from the US Marine corps and my degrees
from the University of Virginia in electronic engineering. Anyways don;t ask how old those
are. Wow I have been out of college longer than most people been alive.
Ok lets get to the FCC Rule on kits.
First off it is Part 15.250
There is alot of Sections so read and only apply what goes with us.
Sec. 15.25 KITS
A TV intereface device, including a cable system terminal device, which is marketed as a kit shall comply with the following requirements:
(a) All Parts necessary for the assembled device to comply with the technical requirements of this part must be supplied with the kit. No mechanism for adjustment that can cause opperation in violation of the requirements of this part shall be accesssible to the builder.
(b) At least two units of the kit shall be assembled in exact accordance with the instructions supplied with the product to be marketed. If all components required to fully complete the kit( other than those specified in paragrapgh (a) of this section which are needed for compliance with the technical provisions and must be included with the kit ) are not normally furnished with the kit , assembly shall be made using the recommended components. The assembled units shall be certified or authorized under the Declaration of Conformity procedure, as appropriate, pursuant to requirements of this part.
(1) The measurement data required for TV interface device subject to certification shall be obtain for each of the two units and submitted with an application for certification pursuant to subpart J of part 2 of this chapter.
(2) The measurement data required for a TV interface device subject to Declaration of Conformity shall be obtained for the units tested and retained on file pursuant to the provisions of subpart J of part 2 of this chapter.
(c) A copy of the exact instructions that will be provided for assembly of the device shall be submitted with an application for certification. Those parts which are not normally furnished shall be detailed in the application for equipment authorization.
(d) In lieu of the label required by sec. 15.19, the following label,along with the label bearing the FCC identifier and other information specified in Sec. Sec. 2.925 and 2.926, shall be included in the kit with instructions to the builder that it shall be attached to the completed kit :
( Name of Grantee)
(FCC Identifier)
This device can be expected to comply with part 15 of the FCC Rules provided it is assembled in exact accordance with the instructions provided with this kit. Operation
is subject to the folowing conditions: (1) This device may not cause harmful interferance, and (2) this device must accept any interference received including interference that may cause undesired operation.
(e) For the purpose of this section, circuit boards used as repair parts for the replacement of electrically identical defective circuit boards are not considered to be kits.
Now this is the rule they gave me that said that all kits fall under this rule and this
is what makes Ramsey and any other transmitting kit illegal unless they have a FCC identifier on them.
They told me to go with FCC rule
Part 15.23 Home Built devices
Which you can build 5 or less for personel use.
Anyways I was really upset when I heard the rule because I just had spent alot of money
and time on making the Ramsey FM100B kit.
Really not what I wanted to hear, and it looks like now I will have to buy a Decade
or some transmitter certified by the FCC. Boy what a bummer because I really
like the Ramsey FM100B transmitter.
Thanks
Hi Carl
The meters had just been callibrated this year and they decided that the new digital
meters would be better.
The new meters ran the radio station around $5000 each. Wow what a price
Rich asked, "But could both of them still be inaccurate?"
That's a heavy question.
If two identical readings from two different meters were the same, but both wrong?
Has that ever happened?
What if the ONE reading an FCC inspection uses is wrong?
It's a thinker.
And to Seanwk40... the rule you quoted on "kits" is all about "TV Interface Devices." It has nothing to do with any other types of kit. It has nothing to do with FM transmitter kits.
Hi Carl
That is what I thought but that what the FCC was trying to pass on to me about
any kit which I thought was incorrect to do. So it would be safe to Transmitt
with a Ramsey kit as long as the power levels are correct. Now the meters
I am getting them from a real broadcast station had to depend on them ,so they kept them in calibration all the time. I told them I did not want them if they were
not in callibration and they showed me receipts and labels on the meters with
the date they had been callibrated. So these will be correct as far as the FCC who
knows. Lets just hope they use callibrated equipment.
I really am thinking about staying with my AM station. I transmitt on 1610 during
the daytime and 1670 at night time and I get really great range.
Thanks
Seanwk40 I want to ask about your AM transmitters but that would be a change of topic and the thread monitors might step in to remind us to stick with the topic.
Hmmm. Ok, so we say the topic was "transmitters" and not just "FM transmitters."
Let's try to pull that off.
What kind of AM transmitters do you run and what kind of antennas, grounds, and how much range and how did you check the range?
Hi Carl
I was running a talking sign transmitter and that went to a 10ft vertical with
a capacitance top hat on it . That gave about 1 1/2 range but I change that
out. Now I run 2 RangeMasters. On my ham towers. I have 32 ground radials at
140 ft each burried. Since the FCC requires you to use a choke between the transmitter and ground so RF cannot reach the ground. This does cut back for a RF ground.
Now my ground radials still work because they will reflect the signal even though
they are not connected to the transmitter in anyway. The purpose of the ground radials is to keep the ground from assorbing any of the RF into the ground,
So you make the ground radials and I hooked about 10 ground rods which are 8 ft
each to the ground radials. Again I have around 32 ground radials at 140 ft each.
Again this is not hooked to the transmitter,so it not counted in the 3 meters.
See the Rf still see this ground system even though the transmitter is not hooked
to it. The RF get reflected off of the ground radials and gives an angle of radiation.
Which improves the distance. I already talked to the FCC about this and they had
no problems since it is not hooked to the transmitter in anyway. I get sometimes
about 2 miles range to 2 1/2 on band conditions.
I kept my ground radial system separate from the transmitter. Now my ground wires
are 4 inches under the ground inside of PVC pipe to keep the wire from corroding.
Also I did not use bare wire.,so it would have extra protection from moisture under the
ground. The PVC pipes are sealed so water does not get into them. then the wire that
does come out of them goes to the ground rods. The 10 ground rounds are place
into a 4 ft dia. circle. The 32 ground radials are hooked onto the 4 ft circular
ground system. This keeps my ground system in compiance with the FCC since it is
not hooked to the transmitter at all. It only sees the RF coming out of the antenna
and refects it from being absorbed by the ground.
Back in the 1960;s and early 1970;s CBers would wet the ground around their
towers to get the same effect as I am getting with this ground system.
The FCC told me as long as the ground system I use is not connected to the transmitter then it it is in compliance. So you could say this ground system is really like a capacitance type system.
Now you can run a ground from the transmitter to ground with a choke for eletrical
ground for lighting strikes. I have that and have a 1 MH Choke very large in size.
This give me protection against lighting.
I have been trying to engineer even a better ground system that does not
hook up to the transmitter and would fall in compliance with the FCC.
I was told to try and make the ground radials a 1/2 wave length long each since
they are not hooked to the transmitter. This would make the ground radials resonate
at the frequency I am tramsmitting at and become more reflective.
The whole point of the ground system is to keep your signal from being absorbed
by the earth ground. So you never need to hook the ground system to the transmitter to make it work. you just need to make it resonate to the frequency you are trying to reflect from the ground.
Anyways I have been able to increase the range and keep to the 3 meter rule.
It would be nice to get a 3 to 4 mile range with staying in compliance with the FCC.
I have not done it yet but I am working on it.
Thanks
Information about the Sadelco 719E meter available on the web indicates that it is designed for the cable industry. Its meters would be calibrated for voltages conducted by a cable system, not those radiated through space.
It would produce a meter reading when an antenna was connected to its input. But that reading is not an accurate measurement of the arriving field intensity unless the "Antenna Factor" of that receive antenna hardware is known and accounted for. A Google search for Antenna Factor will provide more details.
So, while two Sadelco 719E meters might both produce a reading of 250 µV when connected to a dipole antenna, that will not prove that the arriving field intensity is 250 µV/m. It will be much different.
___
Here is a link to an old thread on Part15.us with quite a bit of technical content about elevated and buried r-f ground systems.
http://www.part15.us/forum/part15-forums/general-discussion/ground-radials-questions
Based on comments just filed by Rich, combined with Seanwk40's mention that his meters were used by a licensed FM station, I am guessing that that station used their meters with a specific antenna informed by the "antenna factor," otherwise it would make no sense for them to have such meters.
What we look forward to learning from Seanwk40 is whether he got antennas along with his purchase.
Seanwk40....Can you tell me what meter you got that can measure signals in UV/M!!? Make, model?
And, where you got it!?
Always heard these were far to expensive for the average person or "part 15er" to get, and needs extra equipment to calibrate it properly.
Mark