1. 6 meter Squalo antenna Horizontal polarized Omni directional
Used for monitoring to complement directional antenna
It’s a dipole folded into a square

2. 6 meter Squalo made from 5/8 inch aluminum
28 inch per side
12 inch Gamma match
PVC support
SO239 Connector
Tuning stub made
from 400 Ohm ladder line

3. Gamma match detail
Gimmick capacitor using RG-8 center conductor inserted in gamma match tube
(Sealed with silicone)
SO239 Connector

4. Rough tune in garage by trimming stub length
VSWR=2

5. Designing the RF choke (balun)
#31 and #43 ferrites (2.4 inch diameter) on hand
#31 has better broadband characteristics
Measuring chokes at VHF is challenging
Goal is to rough out a reasonable feedline choke using as few cores as possible for light weight

6. 1T RG-58 thru three #31 cores: 210 Ohms

7. 2T RG-58 thru three #31 cores: 860 Ohms

8. 3T RG-58 thru three #31 cores: 2100 Ohms

9. 2T RG-8 thru three #31 cores: 1400 Ohms
Increased stray capacitance of RG-8 moves resonance too low.
Large loop minimizes capacitance.

10. Balun conclusion
Much better performance using RG-58 due to minimum stray capacitance(>2000 Ohm choking impedance for 3T)
RG-8 is desired for loss and power handling
2T of large RG-8 loops gives >1000 Ohms choking impedance
This will be fine for a general purpose (mediocre performance) antenna

11. Antenna mounted at 30 feet
600 kHz bandwidth VSWR=2 bandwidth (measured thru 100 ft of RG-8)
VSWR=2

12. Conclusions
Power test- 500W for 60 seconds: No arcing, stub does not melt
Very useful addition to antenna arsenal
About 6-10 dB down from STEPPIR with 6 meter element at 55 feet
15 TO 25 dB better for signals to the side or back of STEPPIR
Use when STEPPIR is on another band