BPFs: 1015204080160

Please, see 80M BPF built with large toroids as a coupling inductors in a smaller enclosure.

80M HP BPF comparison (websites can be opened by links):

Insertion Loss 160M Isolation 40M Isolation
VA6AM  < 0.37 dB > 62  dB > 75 dB
DXEngineering (LBS) < 0.18 dB > 45 dB > 47 dB
4O3A < 0.47 dB > 52 dB > 51 dB

 

For 80M BPF I used a twice wider enclosure to fit in all large coils.  I have to use MFJ amplifier coils to make up a large inductance for coils. Some large capacitance made of three doorknob capacitors in parallel. All these factors has brought price up.

Two 50 CFM fans installed to get a suffucient air flow to the larger box.

Recommended BPF Power with antenna VSWR <1.5:

  • 3000W CW/SSB (2500W RTTY) 
  • Without fan installed – 1500W 

Enclosure is Hammond 1411ZU :

  • Without Fan – 17 x 10″x 4″ (42.5 x 25 x 12.5 cm)
  • With Fan Installed –  18″x 10″x 4″ (46 x 25 x 12.5 cm)

hp_80m_bpf

In general, schematics is the 5th order Chebyshev inductor-coupled BPF.

  • Insertion Loss < 0.40 dB
  • Band Isolation ( 160M > 65dB, 40M > 73dB)
  • VSWR < 1.1 (RL > 25 dB) 

80M

Doorknob capacitors allow to use it up to 6000 PEP output power but I’ve never tested it with this power. For this output power some coils should be made with  a larger wire diameter.


Now, I build all 80M BPFs in a smaller box and with T200-2 toroids as coupling coils. Unfortunately, Ameritron coils sold by MFJ are not available all the time and those coils are too fragile.

The enclosure 1444-1783 used, 17″ x 8″ x 3″ with three 60mm fans installed for a better cooling those coils under the current stress.

80M_LY4L 003