Does anyone make a simple RF signal (TV bands) level meter suitable for home use? The ones I've seen are multi hundreds of dollars. I'm going to redo my video distribution network in my home, and I'd like to know that I have the correct signal level at each tap.
My cable company does not provide consistent signal level, either. It would be helpful to check up on them frequently.
An RF meter is not a simple device to build. The frequencies are very high, and component assembly and selection is very critical. There are good reasons why RF meters are expensive.
Your best test is to wire everything up, and see if the pictures are okay. If they are all clean, you know that they are okay.
--
JANA _____
My cable company does not provide consistent signal level, either. It would be helpful to check up on them frequently.
I don't know if this will work, but I would start with a tuner out of a TV or VCR . Either one that is working order , as original, so you can check powered, which is supply pins, IF pins etc before removing or one with known pinning. You would need a supply of about 35V probably. Rectify the IF picture signal output and there may be enough signal to show on a 50uV analogue meter or DVM. For comparative rf strengths, which is all you need. Others on here here would know if it was possible, its just how I would try first. There may not be a linear correspondence between UHF signal levels and IF levels. for each signal
-- Diverse Devices, Southampton, England electronic hints and repair briefs , schematics/manuals list on
I own a Digisat signal strength meter for Direct TV dishes. It was about $150 USD. I suppose its construction matches or exceeds the construction criteria for any TV signal meter. I think if the OP searches well enough he'll come up with something in the price bracket.
The cheapest I've seen a new TV field strength meter was over $300 and that was 30 years ago. It was a Sadelco analog FSM for VHF & UHF TV.
for used, starting at $100.
-- Service to my country? Been there, Done that, and I've got my DD214 to prove it. Member of DAV #85. Michael A. Terrell Central Florida
Our cable company around here intentionally varied the signal level to disrupt the off market cable descramblers. Most of them required the use of an outboard cable box converter which didn't handle signal strength changes to well. On top of that, they varied the frequency slowly. THis also caused issues . it was a deterrent. From what I understand it worked nicely. Their own units handled freq shift and signal level changes of what they were doing just fine.
I always thought each distribution point on the cable center used an AGC output to maintain a fixed level of output on the average but after talking to a long time friend that is a tech in our local center , he verified that is not so and it makes it easy for them to perform this practice..
Now we have digital cable :)
I'm sure your case is not this, most area's I know of are now on a digital system.
For accurate calibration, you really need an Analyzer to cover the whole spectrum if you have a system that has gain settings for different frequency windows.
-- "I'd rather have a bottle in front of me than a frontal lobotomy" http://webpages.charter.net/jamie_5
-- Joe Leikhim K4SAT "The RFI-EMI-GUY"© "Treason doth never prosper: what's the reason? For if it prosper, none dare call it treason." "Follow The Money" ;-P
If that is true, then the FCC would shut them down. The anual 'Proof of performance" required of EVERY CATV system has to be on file, and if it doesn't meed the technical standards, the system can lose their franchise. if the levels are changing you probably have a bad drop, or the tap is bad.
Bullshit. The modulation scheme for a lot of analog scrambling changed the DC reference for the video. The use of non standard video caused the changing levels,
Why should a cable compnay do ANYTHING to help you be a theif?
A specrium anaylzer, or a sweep system is used for proof of perfomance. A calibrarted FSM is used for measuring signal level on a per channel basis. BTDT for United Video. I ran their service center in Cincinnati for four years.
-- Service to my country? Been there, Done that, and I've got my DD214 to prove it. Member of DAV #85. Michael A. Terrell Central Florida
Are you looking for absolute DB readings or just comparative signal quality levels?
How about the following?
Pick up an RF attenuator box (should be fairly inexpensive). Hook it's output up to the most portable TV you've got. Connect the att. input to a point where you know you've got good signal. Crank the attenuator all the way off (no attenuation) and tune in a channel on the TV. Then gradually attenuate the signal to a point where you would consider it unacceptable (totally subjective call.)
Then cart the attenuator-TV combo around and use it to "measure" what you're getting at various points in your distribution wiring. You might even be able to twiddle and mark the attenuator knob at various positions to make comparisons.
I have an attenuator but I've never tried this - you might find the knob hard to adjust, perhaps due to any AGC circuitry in the TV.
It would probably be nowhere near as accurate as a real meter, but it'd give you some data at least, which is better than none at all.
If you do try this, I'd like to hear how it went.
Cheers.
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