You can now help support WorldwideDX when you shop on Amazon at no additional cost to you! Simply follow this Shop on Amazon link first and a portion of any purchase is sent to WorldwideDX to help with site costs.
The Feb 2025 Radioddity Giveaway Results are In! Click Here to see who won!

Reply to thread

Message

If the three trimmer coils for the PLL are that touchy, sounds like maybe someone has worn down the inside of the coil by repeated tweaking? Stabilizing those tiny slugs without making them seize up is easier said than done.

The adjustment range of those coils is usually a couple of channels, or close to it. Makes any tiny disturbance of the slug into a noticeable bump in frequency.

Had a friend years ago who tamed the temperature drift in his Saturn base. Removed a PTC thermistor from a dead camcorder. This is a single piece heating element and thermostat. Served to keep the spinning tape head in the camcorder from getting cold enough to condense moisture from the air. He plastered one of these to the PLL crystal and trimmer cans. Installed a 5-Volt regulator chip on the unswitched DC side of the power supply, and powered the thing from that. So long as it remained plugged in, the PTC would keep the crystals/coils warm, then turn down the heat as the inside of the radio warmed up. Had the only Saturn in town that didn't drift on sideband.

Never could get a part number from him. Said he didn't have service data for that model. Hinted that could have been connected to the decision to scrap it.

Maybe one of these days I'll study that kind of component enough to try obtaining one to do that job. Not this week, though.

73

<blockquote data-quote="nomadradio" data-source="post: 781207" data-attributes="member: 22">If the three trimmer coils for the PLL are that touchy, sounds like maybe someone has worn down the inside of the coil by repeated tweaking? Stabilizing those tiny slugs without making them seize up is easier said than done. The adjustment range of those coils is usually a couple of channels, or close to it. Makes any tiny disturbance of the slug into a noticeable bump in frequency. Had a friend years ago who tamed the temperature drift in his Saturn base. Removed a PTC thermistor from a dead camcorder. This is a single piece heating element and thermostat. Served to keep the spinning tape head in the camcorder from getting cold enough to condense moisture from the air. He plastered one of these to the PLL crystal and trimmer cans. Installed a 5-Volt regulator chip on the unswitched DC side of the power supply, and powered the thing from that. So long as it remained plugged in, the PTC would keep the crystals/coils warm, then turn down the heat as the inside of the radio warmed up. Had the only Saturn in town that didn&#039;t drift on sideband. Never could get a part number from him. Said he didn&#039;t have service data for that model. Hinted that could have been connected to the decision to scrap it. Maybe one of these days I&#039;ll study that kind of component enough to try obtaining one to do that job. Not this week, though.73</blockquote>

[QUOTE="nomadradio, post: 781207, member: 22"] If the three trimmer coils for the PLL are that touchy, sounds like maybe someone has worn down the inside of the coil by repeated tweaking? Stabilizing those tiny slugs without making them seize up is easier said than done. The adjustment range of those coils is usually a couple of channels, or close to it. Makes any tiny disturbance of the slug into a noticeable bump in frequency. Had a friend years ago who tamed the temperature drift in his Saturn base. Removed a PTC thermistor from a dead camcorder. This is a single piece heating element and thermostat. Served to keep the spinning tape head in the camcorder from getting cold enough to condense moisture from the air. He plastered one of these to the PLL crystal and trimmer cans. Installed a 5-Volt regulator chip on the unswitched DC side of the power supply, and powered the thing from that. So long as it remained plugged in, the PTC would keep the crystals/coils warm, then turn down the heat as the inside of the radio warmed up. Had the only Saturn in town that didn't drift on sideband. Never could get a part number from him. Said he didn't have service data for that model. Hinted that could have been connected to the decision to scrap it. Maybe one of these days I'll study that kind of component enough to try obtaining one to do that job. Not this week, though. 73 [/QUOTE]

Top Bottom