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Thursday, October 20, 2016

Cool Jazz from New Zealand as Heard on a Homebrew Superhet Receiver (VIDEO)



I'm making slow but steady progress on this one.  The origin of the project was the beautiful National HRO dial and gearbox that Armand WA1UQO gave me. 

I decided to use a 455 kHz IF because;
1) That was the IF of the old HRO receivers (the ones that won WWII)
2) I had a nice TOYO CM455 crystal mechanical filter that would be good for SSB.
3) I figured it would be easy to add in a wider filter that would be good for AM shortwave listening.
4) I like to keep the IF below the frequency of the VFO.

The wide filter turned out to be harder than I thought, but I think I have finally achieved the selectivity I was looking for.  I'll have a switch on the front panel that will allow me to go from "AM-Wide" to "SSB Narrow." The switch will change the filters and the detectors, and will turn the BFO on and off.

Still to do:  I need a high-pass filter to knock down RFI from nearby AM broadcast transmitter. And an RF gain control would be nice.

I'm really glad Radio New Zealand is there.  It provides welcome relief from the shortwave fire and brimstone.   Radio Romania is also doing a fine job on shortwave.

5 comments:

  1. Replies
    1. Alan:   I've been listening to their on 7425 kHz broadcast to the Pacific, in the morning.  You can see the schedule in the link below.  Unfortunately they change freqs and times from week to week -- this early morning broadcast ends on 29 Oct. So give them a listen this week before they go away! 

      http://www.radionz.co.nz/international/listen

      73  Bill

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  2. Only one "nearby AM broadcast transmitter"? How 'bout a series-tuned L-C 'notch'? Or with a bit of ingenuity a series-parallel "L" or "T" notch? Could be a separate (more versatile) unit. That would leave the rest untouched ...

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