Owen Duffy wrote:

Tony Giacometti wrote in news:CpKdnabH6fWF-
:

here are links to the preamps I use

http://www.iceradioproducts.com/reconly.html

NF=1.8dB and Gain=18dB


http://www.isp.ca/ve3nh/kd9sv.htm

Ok, I can't work with specs like "Noise figure is quite low and the
design appears to have no vices." I am not saying it is bad, it just
doesn't say anything meaninful... well to me anyway.

Still no info on the transceiver, but lets guess it has a NF=8dB.

Transceiver + preamp has a NF of 2dB, which suggests an equivalent noise
floor of about -139dBm (2kHz bandwidth).... provided that the preamp
doesn't generate internal noise due to IMD and which would not be
captured in the 1.8dB spec NF.

ITU-R P.372-8 suggests ambient noise on 1.8MHz in Residential locality
should be about -75dBm+AvgAntGain or about -122dBm, so you should get
noticeably more noise (~17dB) from the loop than from a dummy load. That
would mean the configuration should deliver almost as good a S/N ratio as
possible... even though the S meter reading might be shy.

Again, I am talking about the 160m loop alone. You can't diagnose this
easily with the two loops in parallel.

Owen


I am using a heavily modified Drake R-4c receiver. Sherwood mods.
And I at this point I only built the 80 meter loop as I wanted to make sure
it worked on 80 before I went and built one for 160.

I don't think ITU-R P.372-8 had my neighborhood in mind when it was
composed.

S-9 on this receiver is about the minimum on 160 and S-7 is the minimum on
75.

Much of the time its higher and a royal pain in the arse.