1950 Pilot Jack repair - UK Vintage Radio Repair and Restoration Discussion Forum

martin.m · 14th Mar 2019, 1:58 am

This Pilot radio has been fitted into a Marconi C10A cabinet (not by me) and has been on my "round tuit" list since July 2018, see previous thread https://www.vintage-radio.net/forum/...d.php?t=148298.

When the previous owner had "demonstrated" the set, no stations could be tuned in due to a broken drive cord. There was a quiet muffled hissing from the speaker and the tone control acted as a second volume control. Now on removing the chassis the cause of these problems became clear. Someone had attempted to renovate the set by changing a few capacitors in the audio amp circuit. They had fitted candy stripe 0.1uFs in the tone control circuit and from the anode of the 6V6GT output valve down to chassis. I replaced these with modern 4700pF high voltage caps and changed the grid coupling capacitor together with the two cathode bypass electrolytics, using 100uF 35v axial types. The resistors were measured and found to be within tolerance. Monitoring the HT voltage, I switched on and found that normal operation had been restored though the HT voltage was low at 130 volts. A new 6X5GT rectifier valve restored this to over 220 volts though there was no deterioration in reception with the reduced voltage.

Now for the drive cord. The cord run is more complicated than usual as the tuning scale goes up and down rather than left to right. I drew a diagram first to make sure everything would go in the right direction and managed to get it right first time (beginners' luck). The cord was bought from an Ebay seller based in Australia and came with a useful guide to fitting. One tip proved very handy. Sear the ends of the cord with a hot soldering iron first to prevent fraying.

I am impressed with the overall performance from this little chassis. Short wave reception is very good after dark. Some of the stronger SW stations sound better than the UK Medium Wave ones and seem to have an extended treble response.

14th Mar 2019, 1:58 am	#1
martin.m Hexode Join Date: Mar 2018 Location: Bishop Auckland, County Durham, UK. Posts: 373	1950 Pilot Jack repair This Pilot radio has been fitted into a Marconi C10A cabinet (not by me) and has been on my "round tuit" list since July 2018, see previous thread https://www.vintage-radio.net/forum/...d.php?t=148298. When the previous owner had "demonstrated" the set, no stations could be tuned in due to a broken drive cord. There was a quiet muffled hissing from the speaker and the tone control acted as a second volume control. Now on removing the chassis the cause of these problems became clear. Someone had attempted to renovate the set by changing a few capacitors in the audio amp circuit. They had fitted candy stripe 0.1uFs in the tone control circuit and from the anode of the 6V6GT output valve down to chassis. I replaced these with modern 4700pF high voltage caps and changed the grid coupling capacitor together with the two cathode bypass electrolytics, using 100uF 35v axial types. The resistors were measured and found to be within tolerance. Monitoring the HT voltage, I switched on and found that normal operation had been restored though the HT voltage was low at 130 volts. A new 6X5GT rectifier valve restored this to over 220 volts though there was no deterioration in reception with the reduced voltage. Now for the drive cord. The cord run is more complicated than usual as the tuning scale goes up and down rather than left to right. I drew a diagram first to make sure everything would go in the right direction and managed to get it right first time (beginners' luck). The cord was bought from an Ebay seller based in Australia and came with a useful guide to fitting. One tip proved very handy. Sear the ends of the cord with a hot soldering iron first to prevent fraying. I am impressed with the overall performance from this little chassis. Short wave reception is very good after dark. Some of the stronger SW stations sound better than the UK Medium Wave ones and seem to have an extended treble response. Attached Thumbnails __________________ Regards Martin Last edited by martin.m; 14th Mar 2019 at 2:14 am.