Qrp project – filters

Figure 2: The extra harmonic filter is ready for action in this photo.

I’d used a kit for the PA output LPF in the TX box, but when I added an additional filter between the Progrock and the BS170 driver, I just put it on perf board.

I also cobbled together a little coffin for the filter.  using double sided copper clad board pieces, and a lot of solder.  Note the solder does the most good when it’s used on the inside seams, where there is copper-to-copper contact.

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About ronaldscheckelhoff

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2 Responses to Qrp project – filters

  1. ROBERT M BRAZA says:

    Hello Roland – Thank you for the information on the Alda 103. I have an Alda 103 that has low power and not sure where I should look next. Any information you can supply would be greatly appreciated. Thanks – Bob W1RMB


  2. Hi Bob,

    I wonder if you just purchased the unit, or if it’s been in your possession. Could be something as simple as a bias adjustment, or it could be a worse thing – like a soft driver transistor or output transistor.

    The last time I checked, the output transistors were still available for about $80. Yeah – that’s an ouch. What kind of power supply voltage are you running on the Alda?


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