07-29-2021, 04:36 PM
Coming up to having the cabinet colouring looking respectable and will probably start oiling the wood this weekend. Then the new speaker cloth can be added. Does anyone have tips for applying this to the curved grill?
I've solved one mystery on the voltage measurement discrepancy - something to which I should have paid attention earlier. My Fluke is considerably higher impedance than the 1000 Ohms/volt called for use in the service sheet. When I do the calculation for the first audio 6K7, and include 250,000 for meter resistance, this would drop the measured anode voltage right down to the 60V called in the data table, and not the 140 V indicated with a modern DMM.
Something is still behaving oddly with either the mixer or first IF. On the broadcast band, if I switch the two 6K7s between IF and audio duties, with one combo, the set whistles as stations are tuned in - something is oscillating. With the swap reversed, no whistle, but it sometimes it seems on the verge of it, as if there were some regeneration happening, and the tone of the audio changes strongly with tuning, as if bandwidth is limited. The IF is peaked correctly.
Any thoughts? All valves were bought used, so they could be of questionable condition.
Ed
I've solved one mystery on the voltage measurement discrepancy - something to which I should have paid attention earlier. My Fluke is considerably higher impedance than the 1000 Ohms/volt called for use in the service sheet. When I do the calculation for the first audio 6K7, and include 250,000 for meter resistance, this would drop the measured anode voltage right down to the 60V called in the data table, and not the 140 V indicated with a modern DMM.
Something is still behaving oddly with either the mixer or first IF. On the broadcast band, if I switch the two 6K7s between IF and audio duties, with one combo, the set whistles as stations are tuned in - something is oscillating. With the swap reversed, no whistle, but it sometimes it seems on the verge of it, as if there were some regeneration happening, and the tone of the audio changes strongly with tuning, as if bandwidth is limited. The IF is peaked correctly.
Any thoughts? All valves were bought used, so they could be of questionable condition.
Ed
I don't hold with furniture that talks.
