Hello fellow low-band DXers, Today (after about a year of design and testing) I uploaded 2 new YouTube videos that might be of interest to the group.
The first is a new HI-Z amplifier design based on the OPA814 TI device which has incredible IMD, noise and bandwidth specs. This new amp can be used as a direct drop-in replacement for most 8 or 9 circle HI-Z arrays, and even shares the same footprint as my earlier LMH6622 TI design. This same design can also be used with low-output BOG/BOL antennas. I also describe a second version of this same OPA814 amp that can be used as an active buffer on any terminated closed loop like a Flag, Delta, a pennant, K9AY, DHDL etc. The input impedance of this amp is so high, it can be used as both the termination AND the feed point for simultaneous dual direction RX with 2 feed lines. I explain how using this method on a terminated loop avoids the “13 dB gain tax” we pay when using the traditional passive matching transformer and low-Z amp. Instead of the usually 15-20 dB low-z amp, we can use this amp with only 6 dB gain at the feed point. If you use any kind of terminated loop, this is really worth considering! Also, I provide Gerber, BOM and CPL position files so you can order your own fully SMD assembled boards from JLCPCB for under $40 per board. In the video I walk through the ordering process to get them made at JLCPCB. No soldering small components at home, just mount it in a plastic box. The second video describes my new double-loop RX antenna, the DKAZ which now replaces my 9 circle array. (The DKAZ is a popular MW DX antenna, and is a direct relative of the DHDL popularized by George Wallner AA7JV) I explain why I did this and show how I've built it for 4 direction RX using those HI-Z active buffers at each end. These double loop antennas are much easier to deploy than an 8 or 9 circle, cover multiple octaves (from 160m all the way down to 630m) and have excellent FB, with only about 2 dB less RDF than and active HI-Z vertical array. DKAZ RX Loop video: https://youtu.be/sGrdqgAKXPI <https://youtu.be/sGrdqgAKXPI> HI-Z amp video: https://youtu.be/FxeMp4EAzOY <https://youtu.be/FxeMp4EAzOY> 73, de steve ve6wz _________________ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
