Because of the high maintenance needed to monitor and filter spammers from the RF Cafe Forums, I decided that it would
be best to just archive the pages to make all the good information posted in the past available for review. It is unfortunate
that the scumbags of the world ruin an otherwise useful venue for people wanting to exchanged useful ideas and views.
It seems that the more formal social media like Facebook pretty much dominate this kind of venue anymore anyway, so if
you would like to post something on RF Cafe's
page, please do.
Below are all of the forum threads, including all
the responses to the original posts.
Post subject: RF Problem Posted: Mon Aug 01, 2005 5:51 pm
Aug 01, 2005 5:29 pm
I need some help. I have an rf circuit that I believe has a bad cable or
connector. I have taken a Signal Generator to one side of the circuit and a power meter to the end side. at one
end I need to see a power level at aboiut -27dBM. In order for me to do that I have to attenuate the signal using
an adjustable attenuator. for what ever reason I can only attenuate the signal to -13dBM. Any furthur and I lose
my signal. If I take a 20dB in-line attenuator to the end of the cable I can tune the the power level to the
desired dB(-27dBM). I even put a spectrum analyzer to the circuit and saw the freq I need with the 20dB attenuator
in line and saw the signal perfectly. When I took the in-line attenuator out and went straight through, the
carrier fell beneath a noise floor that was not there when the in-line attenuator in the circuit. Would this have
anything to do with a patially cut cable where there is still center conductor continuity? Or a bad connector?
Post subject: RF ckt
behaviorPosted: Sat Aug 06, 2005 11:19 am
What you're describing is a classic non-linear behavior. In
general, you get nonlinear behavior from active devices (like transistors and FETs) and diodes.
unintentionally create a bad diode if there's corrosion between 2 conductors carrying RF, but it's more likely
that there's a bias problem in your circuit under test.
You haven't given much data on what kind of circuit
you're testing, so the best I can do is the generic vague stuff above. Is your circuit an amplifier, a
variable-gain stage, a modulator, a ...?