LPF 100 and LPF-mini part for sale

We have variants of LPF PCB. First is LPF100 and using low-pass filter 5th order. And the second one is LPF-mini using low-pass filter 3th order. Both PCBs have a SWR meter circuit. All of filters are for 50 ohm.
The LPF100 unit, much better to use if you need attenuation for more harmonics.

Additionally, the board LPF100 have protection circuit if excess a predefined value of SWR. This protection circuit based on transistors VT1, VT2 and relay K16. Sensitivity of the circuit you can set by resistor R11. When the level exceeds the SWR Reflected, defined by resistor R11 value, the transistor VT1 will activate the relay K16. From relay K16, for example, you can cut off voltage for the input relay RX-TX in PA. Or cut off the supply voltage of the first stage PA. Protection scheme is with the "sticky" status, ie VT1 key state is hold until you will connect ESC contact with the ground or OFF/ON the main +13,8 V voltage for the protection board. Hi SWR indication LED VD14, which is connected to the contacts LED SWR and +13,8 V or in any other way, using the relay K16 contacts.

The LPF-mini unit, you can use if you need attenuation up to 30db harmonics. Also, you can use this unit for coupling between TRX and amplifier. Bur needs some recalculation for filter elements if you using amplifier based on Triods or Grounded Grid Tetrode.
LPF100, the filter switching is implemented with 3 options.
  1. to ground one of 01-07 contacts
  2. +5-12v to LPF1-LPF7 contacts
  3. +5v to D0-D3 contacts by following table

On LPF-mini unit, the filter switching is by grounding LPF1-LPF7 contacts.
SWR meter calibration, with 50Ohm dummy load.
Toroids for filters is T50-2, T50-6. With those toroids, filters can pass up to 200w without any extra heating. Briefly, can pass up to 500w. This picture, showing passing through LPF100, 450w power coming from KL-500 amplifier.

LPF100 toroid and winding info:

  1. 160m T50-2, 27 turns, 0,65mm;
  2. 80m T50-2, 20 turns, 0,71mm;
  3. 40m - T50-2, 15 turns, 0,73mm;
  4. 20m T50-6, 11 turns, 0,73mm;
  5. 15m T50-6, 10 turns, 0,78mm;
  6. 10m T50-6, 8 turns, 0,78mm;
  7. 6m diameter mandrel 6mm, 6 turns, 0,78mm;
LPF100 screenshots:


LPF-mini toroid and winding info:

  1. 160m T50-2, 29 turns, 0,65mm;
  2. 80m T50-2, 21 turns, 0,71mm;
  3. 40m - T50-2, 15 turns, 0,73mm;
  4. 20m T50-6, 11 turns, 0,73mm;
  5. 15m T50-6, 9 turns, 0,78mm;
  6. 10m T50-6, 8 turns, 0,78mm;
  7. 6m diameter mandrel 6mm, 7 turns, 0,78mm;
LPF-mini screenshots:


Circuit, pictures for LPF100 Unit, KIT LPF100:


Circuit, pictures for PCB LPF-mini, KIT LPF-mini:

Price:

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