[Elecraft] GaFET Preamp for XV144 transverter

[Don Wilhelm]

Ed,

I can't answer your question directly because "it all depends".

Your preamp has a very low noise figure.  If mounted at the antenna, it 
will swamp out any losses in the feedline (as opposed to mounting it in 
the shack).  However, with good low loss feedline, the loss in 25 feet 
of coax may not be significant.  If you had 200 feet of coax, then you 
would likely want to put the preamp at the antenna.

If you do add the preamp at the antenna:
With 24 dB of gain, you may find that the dynamic range of your 
receiving system is reduced.  That can be increased by reducing the 
front end gain of the XV144 - it involves removing the MAR6 amplifier in 
the XV144.  The instructions are in the XV Owner's Manual.

If you do not currently have the preamp mounted at the antenna, I would 
suggest trying the stock XV144 to see if that meets your operating 
needs.  Should you find that weak signals are difficult to copy, then 
add the preamp at the antenna for improved noise figure of the entire 
system.

If you add the preamp, it may be beneficial to run a separate RX coax 
from the preamp to the XV144 (split RX and TX at 144 MHz) which entails 
removing a relay and adding a jumper.

If you are not into extremely weak signal reception (such as EME), then 
the XV144 without the preamp may be more than adequate.  The typical 
XV144 will receive a signal less than -140 dBm above the receiver noise 
floor with no difficulty.

73,
Don W3FPR

On 3/13/2014 7:24 PM, Edmund Wright wrote:
> I have recently finished aligned and tested an Elecraft XV144 Transverter.  I have an Advanced Receiver Research SP144VDG GasFet 2 meter preamplifier.  Its specs are as follows:
>
>      Noise Figure  < 0,55 dB
>      Gain 24 dB
>      Compression +12 dBm
>      Transceiver Power  <25 watts
>
> Should I use my preamplifier between my Isopole 144 MHz vertical antenna and my XV144 transverter antenna connector?  I will have about 25 feet of coaxial cable between the preamplifier mounted on the antenna and the XV144 transverter.
>
> I will appreciate any comments or suggestions
>
>