Recently I got a new Pre-Amp from Spectrum Communications. Model Type: RP4S.
Here are some details on the Pre-Amp:
STATION RECEIVE PREAMPS metres. 125W through rated on transmit. RF & DC switched 10-26dB panel adjustable gain. 4m model use BF964 with noise figure under 1.5dB. Over-voltage and reverse voltage protected. Protected against transients and EMP at input and output ports. PCB size 68 x 46 x 28mm. Purpose made box 76 x 70 x 38mm (Fitted with SO239 connectors. DC supply 13.5V 80mA.) Type: RP4S. PCB Kit £20.00, PCB Built £30.00, PCB & hardware kit £35.00, Boxed Built £57.00.
I have tried it out on some of my 4m radios, Yaesu FT-847 and my Ascom SE-550.
I tested the 4m pre-amp last night and it is able to pull a signal out of the noise, for example can get a signal from where you could hear nothing..
I had Sean EI4IP and Thos EI2JD on last night on 4m, I then put full attenuation on my 4m radio so that they dissapeared, even with squelch open all I could hear was noise, no trace of a signal. As soon as I put the pre-amp on (on the minimun setting) they appeared out of the noise.
With pre-amp on full they were fully quiet.
The only thing is that with the pre-amp on,even at the low level it highers the floor noise level so that the squelch on the Ascom will not shut off,but squelch level can be adjusted on the Ascom. I noticed it more on the Yaesu FT-847 where the signal meter stays at Zero when the pre-amp is at minimum but the signal meter rises to a Seven when on full.
Having said that I would leave it on the minimum and only use full if needed.
So far I am impressed with it.