Random UnUn Experiments
Field Notes on Experiments with 9:1 UnUn configurations.
The goal is to get as many bands as possible closest to 3:1 SWR to be tunable with an internal rig tuner.
Type 43 Cores
Notes:
17’ of counterpoise wire was deployed in all of these readings.
“Hybrid” - 9 Trifilar Turns. Size: 1.4” (35.55mm) OD. Core: 5943002701. Choke - Size: 1.142” (29.01mm)OD. Core: 2631801202
- “Fatty” - 6 Trifilar Turns. Size: 1.540” Dia (39.12mm) OD. Core: 2643251002
29’ Vertical
41’ Inverted V
71’ Inverted V
Analysis:
This is not an apples to apples comparison. The Hybrid has the advantage of coax isolation. The Fatty is using the coax and the counterpoise together. A 1:1 choke should have been installed beside the Fatty UnUn for parity.
Dispite the disadvantage, the Fatty actually came out on top for lower SWR values, though it’s a rather mixed bag.
Neither of these designs was able to reach the 3:1 goal. A dedicated 10:1 tuner would still be required for either design to work all the bands.
Type 61 Cores
Notes:
FT140-61
“Type 61” - 9 Trifilar Turns. Size: 1.400” (35.56mm) OD. Core: 5961002701
Counterpoise wire was ~50’ 18AWG wire. It was grounded to the tower and left separate (not grounded) for these readings.
Analysis:
The non-grounded deployment did substantially better. The only bands the internal rig tuner on the IC-7300 couldn’t tune were 160M (9:1 {not shown}) and 30M (4.3:1).
I would like to try the Type 43 core with the 148’ wire length for a further comparison.
FT240-61
Notes:
“Type 61” - 9 Trifilar Turns. Size: 2.401” (61mm) OD. Core: 5961003801
Wire: 14AWG Solid Copper
It’s fascinating to see how the core size doesn’t really change the response to the 450Ω load.
73 de VE5REV