Originally Posted by tylerSC
To update this thread, it should be mentioned that MCM now sells a UVSJ from Stellar Labs, and some remaining Radioshacks still have their UVSJ in stock.
I was curious about the performance of the MCM UVSJ and compared four UVSJs for UHF insertion loss:
Radio Shack 15-2586
Antennas Direct EU385CF-1S
For the first measurements, I used a Blonder Tongue HAVM-1UA Frequency Agile Modulator as a stable signal source, and a Sadelco DisplayMax 800 Signal Level Meter. The modulator puts out an analog signal; I used the video carrier for each channel. The Sadelco meter has 0.1 dB resolution.
I was having a problem getting consistent measurements. The Sadelco meter has a built-in calibration reference and at certain intervals will correct its readings. This was difficult for me to deal with when making 0.1 dB resolution measurements, so I switched to my Sadelco 719E meter that has a panel meter with wide 1 dB divisions in the center of the scale that allows me to interpolate to the nearest 0.1 dB.
The Sadelco 719E is on the left; the DisplayMax 800 on the right:
I used the red divisions and the second scale -10 to +20 dBmV.
I would read that as +2.8 dBmV.
To make a measurement, I first connected the modulator to the meter with an F-81 adapter and took a reading. I then substituted the UVSJ, UHF and common ports, for the adapter for the second reading.
There was an attenuator at the output of the modulator and at the input of the meter to try to keep the line "flat" (low SWR).
The MCM 33-2230 does have a higher insertion loss that might make a difference if your marginal signals are at the "Digital Cliff."
The Macom UVSJ has very low loss because it has fewer components.