8meter 40MHz – 41MHz 300 W Transmit – Receive Low Loss Narrow Bandpass Filter

Intended for use with transceivers up to 300 W output, 8m Band-Pass Filter 300W protects the receiver from any out-of-band signals. Bandpass filter uses high Q coils as well as high Q capacitors. Low loss of filter is achieved with careful design and adjustment.

This filter is equally good as a transmitting and as receiving with super low loss (0.13dB).

The filter will reduce the TVI problem or your problem with neighbors with strong HF, 4m, 2m, or 70 cm transmitters. The filter will eliminate your harmonics.

 

What is an 8-meter band (40 – 41 MHz)?

The 8-meter band (40 MHz) is the smallest fraction of the very high frequency (VHF) radio spectrum that is available for amateur radio use. The phrase represents an 8-meter average signal wavelength.

The 8-meter band and the nearby 6-meter band have a lot in common. It does, however, exhibit the improved propagation mechanisms through the F2 ionospheric layer often found at high frequency (HF), which sporadically appears at 6-meters, although being a little lower in frequency.
On the band, sporadic E propagation, which occurs when radio signals bounce off ionized clouds in the lower E zone of the ionosphere, is typical in the summer.

 

The 40 – 41 MHz Band-Pass filter is placed in a brass box and equipped with 2 female “N” type connectors. By e-mail request, possible connector options are: “N” male, SO239, BNC, and 7/16 DIN…

 

300 W 40-41 MHz Band Pass Filter characteristics:

 

Achieved – Measured insertion loss (S21) on a built Band-pass filter:

1.8 MHz = -100 dB
3.5 MHz = -85 dB
7.1 MHz = -66 dB
14.1 MHz = -45 dB
21.2 MHz = -30 dB
28 MHz = -15 dB
40 MHz = – 0.13 dB
40.5 MHz= – 0.13 dB
41 MHz= – 0.13 dB
70.2 MHz = – 26 dB
88 MHz = – 37 dB
98 MHz = – 41 dB
108 MHz = – 45 dB
120 MHz (Third Harmonic) = -50 dB
145 MHz = – 55 dB
432.1 MHz = – 84 dB

 

8m Band-Pass Filter 300W appearance:

 

Maximum power input at SWR:
1:1 = 300 W; 1:1.5 = 210 W; 1:2 = 175 W; 1:3 = 130 W (Intermittence 50%)
 
300 W transmitting and receiving band-pass filter could be used for outdoor mounting. Price difference 9 EUR (plastic box “DB” and bracket).

Feel free to send an e-mail request if you need more.