We're still at or near record highs of 100 degrees here in Arkansas and predicted to last another two weeks. That's very unusual for this time of year and the current atmospheric noise on 160 meters pretty much eliminates any possibility of hearing stations on 160 meters.
Hopefully in the next four to six weeks things will normalize and we can get ready for another 160 meter season. 73 Joel W5ZN -----Original Message----- From: Topband <[email protected]> On Behalf Of VE6WZ_Steve via Topband Sent: Monday, September 7, 2026 12:36 PM To: topband <[email protected]> Subject: Topband: New HI-Z amp design and active loop antenna 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 _________________ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
