That's an interesting idea. However, in this rural QTH in SW Missouri, there are no AM BCB stations closer than 40 or 50 miles. And none of those are over 5 kW. No nearby hams on 160m. And on top of that, we have directional Beverage antennas that can feed an optional preamp with the W7IUV modifications, www.w0btu.com/W0BTU-broadband-preamps.html .
I have never had to use any type of high-pass or band-pass filter on 160. Here, IMD is not an issue (unless I have my noise blanker set too high ;-) If I decided to build a WF, a low noise figure seems to be more important than a preamp with as high an intercept point as possible. With all of that in mind, any suggestions for a very low noise figure, high-gain preamp with only a modest IP3 spec for a WF? 73, Mike www.w0btu.com On Wed, Sep 9, 2015 at 4:35 PM, Richard (Rick) Karlquist < rich...@karlquist.com> wrote: > > > On 9/9/2015 4:04 AM, Andrew Ikin wrote: > > Both amps, being single ended are likely to be susceptible to second >> order IMD from BC AM band Tx. Whether one would notice much difference >> with a amp. with a less than 1dB NF versus the above mentioned types >> > > It would not be hard to use two HMC-580's in push pull with > input and output transformers. The output transformer could > be used to feed in the DC, eliminating the RF chokes. This > should improve second order IMD by 20 to 40 dB, depending > on how well matched the amplifiers are. It would also increase > 3rd order intercept by 3 dB. > > Rick N6Rk > > _________________ Topband Reflector Archives - http://www.contesting.com/_topband