BPFs: 1015204080160LPF-160BPF

Please, see 40M High Power BPF made in a smaller enclosure.

40M HP BPF comparison (websites can be opened by links):

Insertion Loss 80M Isolation 20M Isolation
VA6AM  < 0.3 dB > 60  dB > 82 dB*
DXEngineering (LBS) < 0.4 dB > 57 dB > 65 dB
DXEngineering (DX-S) < 0.3 dB > 62 dB > 50 dB
4O3A < 0.4 dB > 56 dB > 56 dB 

* – 82dB Isolation level in 40M BPF achieved with coupling coils made on Iron Powder cores. With air coils this number is better than -70dB.

Recommended Band Pass filter applied power with antenna VSWR <1.5:

  • 2000W (2500W PEP) with Iron Powder cores and 50CFM fan installed

Enclosure is Hammond 1411ZU :

  • Without Fan – 17 x 4″x 5″ (42.5 x 10.5 x 12.5 cm)
  •  With Fan Installed –  18.5″x 4″x 5″ (46 x 10.5 x 12.5 cm)

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

HP 40M BPF with large Iron Powder toroids as coupling inductors.

40M_Toroids 001

  • Insertion Loss < 0.3 dB
  • Band Isolation ( 80M > -60dB, 20M > -82dB , 15M >-100dB)
  • VSWR < 1.1 (RL > 26 dB)

Please, see a graph below with T200-2 used as coupling inductors :

  • More than -80dB isolation level can be achieved for 20M band  if large toroids used instead of large coupling air coils (see photo above). Coils made on toroids have less stray capacitance (parasitic capacitance between coil turns) and as a result higher band isolation gets improved.
  • T200-2 iron power core can be used up to 2000W of amplifier output power without any problem (not tested above 2000W of output power).  

PJ4K_40MPJ4K_40M_WidePJ4K_40M_InBand


Another 40M BPF made using coupling coils made as regular air coils.

Recommended Band Pass filter applied power with antenna VSWR <1.5:

  • 100 CFM fan installed – 3000W CW/SSB (2500W RTTY) 
  • 50 CFM fan installed – 2000W  CW/SSB (1500W RTTY)
  • Without fan installed – 1500W PEP

hp_40m

  • Insertion Loss < 0.32 dB
  • Band Isolation ( 80M > -60dB, 20M > -70dB, 15M >-100dB)
  • VSWR < 1.1 (RL > 26 dB)

40m_bpf

VSWR and Insertion Loss inside the 40M band:

40_bpf_inband

On a picture below you can see 40 and 80 meter band BPFs.  80M BPF box twice deeper than all other band BPF boxes.

Matt_40_80