That is conveniently left out of all the sales information. The take-away when reading the brochure at Solid Signal is the antenna used with the preamp unpowered is the same as no preamp at all.Televes active antennas do not have any insertion loss when used in active mode with the amplifier receiving power and working (which is how they are designed to be used) other than an around 0.5dB loss due to the input saw LTE filter. The passive pass-through does incur significant insertion loss and it is intended as an "auxiliary mode" of sorts only, when the available signals are so strong that said insertion loss is irrelevant, or more importantly in the event power fails to reach the preamp for any reason so that the antenna continues to work, albeit at a lowered performance level. Other active antennas do not do this and just fail to work when power fails, this behavior is also better than the alternative of a mast mounted amplifier failing to receive power and interrupting signal flow altogether.
Therefore any spectrum analyzer screenshots, parameter values, and/or conclusions drawn with a DAT LR or any other Televes amplified antenna used in passive mode with the addition of an external third party preamp will show a very significantly diminished performance due to the C/N degradation incurred in that set up. Conclusions, measurements and graph representations derived from such an exercise are apples-to-oranges, uninformed, inaccurate, and in summary, just plain wrong.
Thanks for confirming the 300 ohms. I used one of my calibrated 4:1 coax baluns to take a more careful look at the preamp. I am NOT just sticking a 50 ohm noise source on a 300 ohm preamp. I'm using a TPX-75-4 50:75 ohm transformer (0.4 dB insertion loss) and the 4:1 coax balun (~0.2 dB insertion loss) to reduce the ENR of the Ailtech noise source. This produced an improved noise figure of 4-5 dB on UHF. I still consider that to be poor though for a preamp claimed to be <2 dB. If you have any other measurement tips I'd be happy to hear them.The NF values posted by this individual are also way off, probably because the error is being carried over and the methodology is flawed. It is also unknown how those supposed insertion losses are being measured, since the dipole input where the preamp resides is adapted to the antenna impedance of around 300 ohm balanced (depending on the particular antenna) and not at 50 or 75 ohms, so measuring at the input of the amplifier with a 50 ohm unbalanced meter will not provide any real valuable information.
I'm not sure what you're talking about when you say "comparing noise floors to measure NF." I think you may be conflating NF measurement with comparing antenna gain by equalizing noise floors for antennas with different preamps and coax runs.I would encourage any interested readers to disregard this misinformation and reach out to Televes directly with any doubts, concerns or for accurate feedback. The RED (radio equipment directive) specifies the FoM (figure of merit) for the characterization of active antennas. The exercise of comparing noise floors to measure NF is incorrect and leads to wrong conclusions. The FoM is related to the antenna gain, the noise power and the NF of the amplifier. Televes active antennas are RED compliant and have been characterized and tested by the most prestigious laboratory in the industry, PKM in Germany.
I'd like to point out to readers that the poster is the head sales rep for Televes in North America so he'll never say anything negative about Televes products. He has a strong incentive (keeping his job ) in emphasizing the positive and ignoring the negative and every incentive to discredit me as someone who doesn't know what he's doing. I'm just an old retired test engineer with no financial incentive one way or the other to recommend or not recommend any product. My only incentive is the fun of testing these things and hoping someone will get a little bit better TV reception.To reiterate, the posted values and graphs by this poster in this and several other threads in this forum are wrong. They do not represent the real performance of a DAT LR antenna when used as intended and, although the time and dedication are very much appreciated, they portrait a very misleading picture of the product -probably unintended- and are to be deemed completely irrelevant.
Hi Ray,Sounding good! Volume consistent with surrounding channels.
Another channel scan? Well, maybe I'll get lucky and get rid of the extra 7.1-3 that I picked up on the last scan! Will do it this afternoon and let you know.
Thanks for the idea. I took a brief look at that earlier and I don't think that's the case. Here's another look.Chuck,
A thought about your readings. The Televes preamp (unlike nearly all other consumer preamps) has a built in AGC and no way to disable that to my knowledge. It sounds like you are feeding it a very strong signal for your testing. Is it possible that the AGC action is throwing off your readings?
Yes & NoHi Ben,
Can you pick up KQRO-LD 45 again? I came out to the site just now. The preamplifier and receiver had died. So, I bypassed the preamp and swapped receivers.