Hey folks
It has been over 2 decades since I have put up a broadcast TV aerial. I guess it was 2 decades ago I put up a couple of dishes. I never put them up for a living, but I put up quite a few back then for friends and family. Never had any instrumentation, but that was a lot less necessary when you could judge signal strength by looking at the size of the "snow" storm. I just put up an attic antenna. The online databases are really nice as to being able to judge what I might get and where to point the antenna.
I did some reading and it seemed like looking at the pilot strength might be a good proxy for signal strength in general, but have discovered that just looking at the entire 6MHz channel seems to give steadier readings and hence more useful. I have been too busy to do more antenna tweaking since getting a meter, but I do expect I should be able to improve a couple of marginal signals and possibly add a few.
I recently bought a Trilithic Model one on ebay for about $50. Has no battery pack so you have to keep it plugged in during use, though it wouldn't be hard to improvise a battery if one needed that capability. It run's quite happily plugged into the power pack with no battery present.
The biggest downside is that the box was targeted to the CATV market, so there is no channel plan for NTSC much less ATSC. I entered all of the US Broadcast channels manually, which was rather time consuming. What seemed to work best is to choose the "Digital" option for each channel and enter a bandwidth of 5.5 or 6. That gives quite stable readings. Of course the scale is arbitrary. Each channel can be enabled of disabled, so if you go to different region you can easily change the channels scanned if you have spent the time to enter all channels like I did.
Fortunately, you can save the channel plan (and you will want to do so periodically as you enter your info). Oddly, the favorites function is not saved (not sure if it would be saved if you have a battery attached) but choosing 8 channels is fairly quick work.
One feature that I expect will be really handy is the ability to choose up to 8 "favorite" channels and view the strength of those in near real-time (it takes 3 seconds/channel) using this "Tilt" function. My thoughts are you put in some of the medium strength channels as well as the fringe channels, and that way you can make sure you don't lose those medium channels in the process of tweaking for the weaker channels. In the most sensitive scale I can see channels on the meter too weak for the TV to recognize, so it would appear it is going to of sufficient sensitivity to do what I want.
Specs are as follows:
Frequency Range 5MHz~870MHz
Tuning Resolution 10kHz
LEVEL Mode
-Signal Measurement -25dBmV to +60dBmV
-Range 35dB?V to 120dB?V
Measurement 0.1dB Resolution
Measurement Accuracy :
-LEVEL Mode ±1.5dB at 25 C
-SCAN Mode ±2dB at 25 C
-Variation with Temp. ±2dB from -10 C to +40 C
TILT/FAVORITE Mode
-Number of Channels Up to 8, user-selected
-Data Display Bar graph or list of measured levels
-TILT Measurement Calculated as the
difference in amplitude between the first and
last carriers in the displayed group
SCAN Mode
-Channels Scanned Up to 140, maximum
-Scanning Rate 3 channels/second
-Displayed Amplitude 80dB, maximum Range
-Vertical Display 1, 2, 5, 10dB/division
-Frequency Span Settable from approximately
-100MHz span to full span in 5 ranges
SPECTRUM Mode
-Displayed Amplitude 80dB, maximum Range
-Frequency Span Settable from 2MHz to
50MHz, in 5 steps or full span.
-Amplitude Scale 1, 2, 5, 10dB/division
I have programmed in some FM channel, but I suspect the minimum bandwidth setting of .30 MHz will probably mean I won't be able to make much use in that band. It will be fun to experiment with that.
I would be interested in comparing notes with anyone else using this, or similar cable TV devices for signal strength measurements on ATSC stations. I do realize that there is a lot more than just signal strength, but signal strength is a VERY good place to start IMHO. If you have only one or two problem channels then clunkier solutions (E. G. tuner diagnostics) can fill in the gaps.
One more thing. Since the biggest downside to the Trilithic Model One is the time involved to configure a channel plan, if anyone can locate the PC software (assuming it will run under modern windows) you might be able to make the process slightly less time consuming,
