30-04-2011, 08:01 PM
That's the very one I made. Excellent scan Joe!
The only problem is that which I referred to above - the Toko coil used in the VFO, L1, is now unobtainable, but as I outlined above, I had no problems winding an alternative on a scrap Toko core. (Only one side of the original Toko coil was used anyway). The VFO worked straight off, but was a little high in frequency, so rather than adding turns to the coil, which would have been fiddly, I added a small cap in parallel with the tuning cap to increase the capacitance and thus, lower the frequency. Obviously unless the correct Toko coil can be found, which is most unlikely, a frquency counter and scope is helpful in setting up the frequency coverage, or it would be a case of tunnig across the MW band until the modulator makes its presence known.
I like Stef Niewdomski's articles - he's been writing for decades and I've made a few of this designs, which have always worked. The artwork for the PCBs for this design is excellent IHMO.
Nice little home-brew project!
David.
The only problem is that which I referred to above - the Toko coil used in the VFO, L1, is now unobtainable, but as I outlined above, I had no problems winding an alternative on a scrap Toko core. (Only one side of the original Toko coil was used anyway). The VFO worked straight off, but was a little high in frequency, so rather than adding turns to the coil, which would have been fiddly, I added a small cap in parallel with the tuning cap to increase the capacitance and thus, lower the frequency. Obviously unless the correct Toko coil can be found, which is most unlikely, a frquency counter and scope is helpful in setting up the frequency coverage, or it would be a case of tunnig across the MW band until the modulator makes its presence known.
I like Stef Niewdomski's articles - he's been writing for decades and I've made a few of this designs, which have always worked. The artwork for the PCBs for this design is excellent IHMO.
Nice little home-brew project!
David.
