Mike, is there any reason why you tested it above 20 MHz? That's outside the 1026's specified frequency range.
73, Mike W0BTU On Tue, Mar 17, 2020, 9:07 AM Michael Tope <w...@dellroy.com> wrote: > I just happen to have a spare MFJ-1026 at home. I did a real quick test > using my FT1000MP MK-V while powering the MFJ-1026 from an Astron > supply. Similar to your results, Steve, I got about a 12 to 14 dB > increase in the noise floor on 10 meters when the MFJ unit was turned on > and connected to the MK-V's main antenna input versus when the MFJ unit > was powered off. This suggests you would have to resort to having > low-noise pre-amps ahead of each of the MFJ-102x two signal paths and > the right amount of attenuation after the MFJ-102x's combined output to > work in your particular very low noise situation. > > Since the main antenna path is normally bypassed for transmit, to put a > pre-amp ahead of the main antenna path you would have to either move > that MFJ-102x out of the transmit path by putting it in a receive-path > breakout-loop that is common on many modern transceivers (e.g. between > RX_OUT and RX_IN jacks), or you would have to have add a dedicated T/R > bypass scheme for the external main path pre-amp. > > FWIW, I also made some gain measurement on my MFJ-1026 (both main and > sense path gain controls fully clockwise): > > Main Antenna Path Gain: > 10 Meters: 4dB > 15 Meters: 3dB > > Sense Antenna Path Gain (sense-path pre-amp on and internal jumpers set > for maximum gain): > 10 Meters: 0.5dB > 15 Meters: 1.6dB > > Difference between having Sense Path Pre-Amp On vs Off: > 10 Meters: 8dB > 15 Meters: 9dB > > I used an Elecraft XG3 as the signal source and an HP141T to measure > amplitude. > > 73, Mike W4EF................... > > _________________ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector