|I was in the local RS the other day poking around for accessories to use with my latest "toy", a Icom R7000. They have a neat little in-line preamp for around $13, but they do NOT have a power injector which would allow this to work.|
BTW, even Lowes sells the in-line preamps but NO DC injector.
Looking further, I noticed this preamp which has the DC injector, and a DC block.
I already have an older Channel Master in-line preamp which covers 50-900 Mhz. Since the R7000 goes to 2 Ghz, I thought this preamp would be a good match.
This amp has a very small advantage over the CM, but the coverage is much more broad.
Using a RS Discone and either amp, I can hear AM Aircraft signals very clearly that are 'in the noise' without the amps.
Using the RS and CM amps to listen in on an Es opening on 6 Meters yesterday, revealed a dramatic increase in the reability of the signals. Although the Discone antenna is great for what it is, it IS a ZERO gain antenna, so some help is necessary. I would liked to put the preamp AT the antenna where it would do the most good, but since I use the antenna to transmit on (for now), it's a big NO.
It took me a while to figger out the 'manual'. Never having had a scanner before (or a preamp such as this), it was a little confusing.
I couldn't figure out why they put a DC block on the antenna side of the amp. I later realized it was there in case you use a 75 ohm to 300 ohm transformer at the antenna. In this case, it would present a short.
I ended up leaving that DC block there and putting another on the input side. That way, there is NO possibility that a reverse connection will produce a DC voltage into the radio. With my luck, this would be likely!!! Checking several different very weak signal UHF stations, the DC block had NO effect on the signal. Cheap insurance!
BTW, the DC block is a 1000 pf cap in series with the center conductor.
I asked if I could return the unit if I was unhappy with it. I was told "certainly" which made me feel good. The unit works so well, I'm keeping it.
When I get my 'real antennas' up, the preamp will go UP at the antenna. That way, the feedline loss will not add to the system noise figure....
I like it!