My early tests with LZ1AQ breadboard performance are very encouraging, even with the loop still located in my basement below ground.
So far, my prototype wideband magnetic loop still lives in my basement, hanging from the ceiling. Not surprising, since the amplifier is on a breadboard. But I have found that even with its poor location, this wideband loop works great on the AM broadcast band. LW and MW signal strengths are comparable to my outdoor antennas.
As previously mentioned, though, the LZ1AQ breadboard performance drops off at higher frequencies. So I though I would do a comparison test with WWV at 10 MHz one morning.
I connected the loop to a balun and power supply using 10 meters of CAT7. After the balun, there is a run of 20 meters RG58 to the receiver in the shack. My amplifier runs on 10 VDC and draws about 130 mA. For my wideband loop testing, I am using the Perseus receiver with SDR Console software.
For comparison, my normal HF station results are shown on the right. The receiver is the Flex 6300 using SmartSDR, connected to a small Yagi on a 50 foot tower. (Full disclosure: my loop is oriented towards WWV but the beam is off the back.)
You can see the loop versus beam performance in the above picture.
LZ1AQ Breadboard Performance – Amazingly Good
When I ran this test of LZ1AQ breadboard performance, I was actually startled at the results. Signal strength from my basement loop was identical to the external beam antenna. My measurement was -92 dBm or around S6 on both receivers.
However, the noise floor was about 10 dB higher with the loop. This is something I have noticed across the 1-10 MHz range. Weaker signals get buried in noise when the loop is used. Whether this is mainly due to the Noise Figure of the loop, or the lousy basement location, or both is to be determined.
Keep in mind also that the performance characteristics are different between the Flex and Perseus.
Nevertheless, I am encouraged enough to get some PCB made and try the LZ1AQ amplifier in the real world.