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sabato 3 gennaio 2015

A simple method for accurate tuning of a regen receiver

The short video below shows a simple method for accurate tuning of a regenerative receiver, with the help of a small portable radio with digital frequency readout, 1 kHz tuning accuracy (or better) and SSB mode.
In my video, the regen receiver is the one described in some of my recent posts.
The portable radio is the Tecsun PL-660, that I recently bought on the web to use it for my first experiments as a MW DXer.
Please consider that I have made further modifications on my tube regen, always with the kind help of some members of the regenrx list on Yahoo. The up-to-date schematics is here below:

In particular, I have removed completely the wiring that I had added for the band switch, because it had resulted in a negligible improvement as a feature, while it had caused big problems in terms of spurious resonances that led the detector to demodulate strong local FM stations.
Now the tuning range is again the original 1330 kHz to 3735 kHz, but (thanks to a suggetion from Bernd, a member of the regenrx list) I discovered that I can move it down to approx. 730-2035 kHz, without any modification in the circuit or the tuning coil, by simply inserting a small pack of four ferrite rods in the core of the coil former. I suppose that the tuning range could be moved further down in the MW band by adding another ferrite rod in the pack.
That said, please find here below my short video about a simple method for accurate tuning of a homebrewed regenerative receiver. I hope you will find it of some interest for you.

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