25-10-2020, 05:13 PM
Hi.
Well after 56 years I cobbled up the EE8 reflexed radio using one AF114 instead of the 116, it had tin whiskers but I blasted them with a charged cap at 150v. I matched all the values as per the old circuit with the exception of the HF choke which is a modern 2mh item. As I thought the resultant AF waweform is horrible but in fact that little one transistor circuit drove a pair of high impedance phones quite easily and surprisingly sounded quite good. Again I tried different combinations of diodes and got an improvement in output by fitting another diode with its cathode connected to the anode of the existing diode and the new diodes anode grounded. There was a noticeable improvement in audio.
Another improvement which didn't reduce top end audio noticeably was to increase the 47nf on the cathode of the detector Diode RF filter, that also cleaned up some RF leakage but that could be due to rubbish modem chokes with high capacitance. Getting good RFCs these days is like looking for a needle in a haystack.
Well after 56 years I cobbled up the EE8 reflexed radio using one AF114 instead of the 116, it had tin whiskers but I blasted them with a charged cap at 150v. I matched all the values as per the old circuit with the exception of the HF choke which is a modern 2mh item. As I thought the resultant AF waweform is horrible but in fact that little one transistor circuit drove a pair of high impedance phones quite easily and surprisingly sounded quite good. Again I tried different combinations of diodes and got an improvement in output by fitting another diode with its cathode connected to the anode of the existing diode and the new diodes anode grounded. There was a noticeable improvement in audio.
Another improvement which didn't reduce top end audio noticeably was to increase the 47nf on the cathode of the detector Diode RF filter, that also cleaned up some RF leakage but that could be due to rubbish modem chokes with high capacitance. Getting good RFCs these days is like looking for a needle in a haystack.
