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I had a SX-101A a few yrs back. In the process of restoring it I found that there was a large "Heating" resistor on the underside of the chasis, the purpose of which is to keep the oscillator at a temp so it does not drift. It was inop and I could not find a direct replacement. So, I found smaller heating resistors that I mounted on a copper strip which I cut to fit the old resistor standoff mounts. It worked all OK, and no drift! Hope that helps. - alan K9MBQ -----Original Message-----
From: <[email protected]> Sent: Jul 1, 2024 11:55 AM To: [email protected] <[email protected]> Subject: Re: [HallicraftersRadios] SX-101 A Drift ? Thanks for asking!? You questions made me look at this problem critically!? I only work CW on 40 and 20, so my remarks will be confined to that area of operation!
The drift is not as bad on 20 as 40, but still there.? It is a "slow" drift!? I can bring it back using either the tuning control, or pitch adjustment.? I have wonder if the "drift" was in the audio circuits, and not in the RF portion. Is such a thing possible? When I put the 100 kc marker on, it still drifts.
It's a "slow" drift.? Sometimes it kind of "jumps" but not too often.? The pitch will go up and down.? I'll have to pay more attention to the change in frequency!? Its on and old Hallicrafter SX-101 with a slid-rule type dial.? Not a lot of accuracy like on a digital read out!
Thank you for you thought!? If you have any more, please let me know!
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Also many thanks to others who have offered ideas!? I will address each on!? MANY thanks to all!
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George KN3PAT
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On Sunday, June 30, 2024 at 09:15:08 PM EDT, Richard Knoppow <1oldlens1@...> wrote:
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What is the nature of the drift? That might be a clue. Is it steady
in one direction or does it drift back and forth. Does it jump (jumping is frequently due to bad silver mica caps). Can you get to the components with a heat gun or freeze mist? Real freeze mist is hard to obtain these days but turning a can of compressed air upside down will work quite well. Heating and cooling might help to isolate what is causing the problem. Another trick is to use a Variac to vary the line voltage, does the drift follow the voltage? usually, there will be some variation but the amount might give you a clue. On 6/30/2024 2:38 PM, Anthony W. DePrato wrote: if it drifts still after 6 hrs? i would look for a bad mica cap in the-- Richard Knoppow Los Angeles WB6KBL SKCC 19998 ? |
