Hi Folks, I have a completed working 8.3 Lite with an LVDS Si570. However gut feeling said it was bit deaf on 20m up. 80m and 40m appear fine.
Having stuck the little BPF's on an analyser the two high frequency ones appear way out, for no apparent reason. Put analyser across the secondaries with tracking generator across the input. 80/40m filter appears spot on with a peak at 80m and again at 40m with minimum loss. 20m Filter shows two peaks, one at 7.36MHz and another at 16.59MHz with a smooth dip in between. Roughly 4dB loss at the peaks and -11dB at 30m, -9dB at 20m and -8dB at 17m. Transferring analyser to input shows two notches, one at 7.36MHz and other at 16.59MHz. I've counted the turns again, checked the right capacitors are in the right place and primary and secondaries are connected correctly. The 15/12/10m filter is just as far out. Peaks at 12.8MHz and 21.8MHz, down -7dB and -11dB respectively. Loss at 15m is -10dB, 12m is -18dB and 10m is -24dB. Notch at 12.8MHz and 23.6MHz. Again right capacitors, turns, correct coloured toroids (Hi!) etc. I didn't expect what I am seeing so am I just measuring these wrongly and they should look like that or is something really out ? Thanks Duncan -- Duncan Clark
