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SX-101 A Drift

george deitz All Messages By This Member #30418 My 101 drifts, and from what I read is a common problem.? I see several possible cures for it. 1) VFO because it has a drift correction adjustment that is simple to manipulate. This from a post on 2/2015.? I can't find any info on this adjustment?? Where is that adjustment located and how do you do it? 2)Re-cap it.? I dread the thought of working on this beast.? But does anyone recommend a good re-cap kit? 3)Replace the 6c4 with a 7 pin pentode?? Any recommendations on the pentode.? Is this an easy "drop in" replacement? I use this receiver along with my HT-32A.? A lot of enjoyment, even with the drift! Thanks for the help! George-KN3PAT
Anthony W. DePrato All Messages By This Member #30422 i had the SX 101A version and never had any drift problems the 101 may have been different but can not recall hearing it was a problem. did you check the heater resister ? it is across the AC line and keeps the filaments lit to stop any VFO drift. i think the 101 may have also had this. 73 Tony WA4JQS At 06:57 AM 6/30/2024 -0700, you wrote: toggle quoted message Show quoted text My 101 drifts, and from what I read is a common problem.? I see several possible cures for it. 1) VFO because it has a drift correction adjustment that is simple to manipulate. This from a post on 2/2015.? I can't find any info on this adjustment?? Where is that adjustment located and how do you do it? 2)Re-cap it.? I dread the thought of working on this beast.? But does anyone recommend a good re-cap kit? 3)Replace the 6c4 with a 7 pin pentode?? Any recommendations on the pentode.? Is this an easy "drop in" replacement? I use this receiver along with my HT-32A.? A lot of enjoyment, even with the drift! Thanks for the help! George-KN3PAT Anthony W.(Tony) DePrato WA4JQS Extra Since 1962 CQ DX HALL OF FAME #35 HONOR ROLL CW RTTY PHONE #1 MOST WANTED VP8SSI 1992 #1 MOST WANTED 3Y0PI??? 1994 Founder :South Sandwich Island DX Group Founder : Ky Dx Group WA4LLK 1988 Founder: Lake Cumberland Amateur Radio Assoc. 1974 Calls Held: VP8SSI VP8BZL 3Y0PI ???????????????? V31SS ZD8JQS WA4JQS/4K1 ????????????????? WA4JQS/KC4 WA4JQS/ZS1
george deitz All Messages By This Member #30423 No, I have not checked that. I will check it when I pull it apart.? Adding it to my list! Even after its been on for maybe 6 or more hours it still drifts.
Anthony W. DePrato All Messages By This Member #30424 if it drifts still after 6 hrs? i would look for a bad mica cap in the vfo also. 73 Tony wa4jqs At 01:30 PM 6/30/2024 -0700, you wrote: toggle quoted message Show quoted text No, I have not checked that. I will check it when I pull it apart.? Adding it to my list! Even after its been on for maybe 6 or more hours it still drifts. Anthony W.(Tony) DePrato WA4JQS Extra Since 1962 CQ DX HALL OF FAME #35 HONOR ROLL CW RTTY PHONE #1 MOST WANTED VP8SSI 1992 #1 MOST WANTED 3Y0PI??? 1994 Founder :South Sandwich Island DX Group Founder : Ky Dx Group WA4LLK 1988 Founder: Lake Cumberland Amateur Radio Assoc. 1974 Calls Held: VP8SSI VP8BZL 3Y0PI ???????????????? V31SS ZD8JQS WA4JQS/4K1 ????????????????? WA4JQS/KC4 WA4JQS/ZS1
Richard Knoppow All Messages By This Member #30427 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. toggle quoted message Show quoted text 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 vfo also. 73 Tony wa4jqs -- Richard Knoppow Los Angeles WB6KBL SKCC 19998
george deitz All Messages By This Member #30428 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! Also many thanks to others who have offered ideas!? I will address each on!? MANY thanks to all! George KN3PAT On Sunday, June 30, 2024 at 09:15:08 PM EDT, Richard Knoppow <1oldlens1@...> wrote: 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. toggle quoted message Show quoted text 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 vfo also. 73 Tony wa4jqs -- Richard Knoppow Los Angeles WB6KBL SKCC 19998
thoyer All Messages By This Member #30430 If you mostly operate CW (as do I), did you check the "drift" on AM? Could be the BFO? Tom W3TA On Monday, July 1, 2024 at 11:55:55 AM EDT, george deitz via groups.io <georgedeitz@...> wrote: 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! Also many thanks to others who have offered ideas!? I will address each on!? MANY thanks to all! George KN3PAT On Sunday, June 30, 2024 at 09:15:08 PM EDT, Richard Knoppow <1oldlens1@...> wrote: 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. toggle quoted message Show quoted text 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 vfo also. 73 Tony wa4jqs -- Richard Knoppow Los Angeles WB6KBL SKCC 19998
Alan Swinger All Messages By This Member #30435 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 toggle quoted message Show quoted text -----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! ? Also many thanks to others who have offered ideas!? I will address each on!? MANY thanks to all! ? George KN3PAT ? ? ? On Sunday, June 30, 2024 at 09:15:08 PM EDT, Richard Knoppow <1oldlens1@...> wrote: ? ? 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 vfo also. 73 Tony wa4jqs -- Richard Knoppow Los Angeles WB6KBL SKCC 19998 ?
Richard Knoppow All Messages By This Member #30446 About the only way to check drift on AM is to listen to the local oscillator on another receiver. Since the other receiver may not be stable the LO should be beat against a stable oscillator, perhaps a crystal calibrator. Otherwise how are you to tell if the LO is drifting? With no BFO there is only gross drift such as will put the station out of tune. Because the BFO operates at a frequency not commonly covered by receivers it will not be possible to hear it against a stable oscillator. BFOs do drift but since they usually operate at low frequencies, the drift is usually small compared to the local oscillator. OTOH, on my HQ-129-X I can tell the BFO drifts in comparison to the crystal flter. If I tune a signal exactly to the peak of the crystal filter at its narrowest (about 50 Hz) and zero beat it, after some time, especially if the receiver is cold, the BFO will change. This drift is quite large compared to what could be accounted for by drift in the filter crystal. Its plain thermal drift. If I adjust the BFO after the set has heated up for an hour there is no longer any drift. The HQ-129-X despite being something of an antique is fairly stable. toggle quoted message Show quoted text On 7/1/2024 10:19 AM, thoyer via groups.io wrote: If you mostly operate CW (as do I), did you check the "drift" on AM? Could be the BFO? Tom W3TA -- Richard Knoppow Los Angeles WB6KBL SKCC 19998
Richard Knoppow All Messages By This Member #30447 That thing was probably a Dampp-Chaser (with two P's). They were used in some receivers and in other equipment to keep moisture out. Just a low power heating element. I don't want to say they are not made any more because I think I saw one on the web but a search will determine that. toggle quoted message Show quoted text On 7/1/2024 11:21 AM, Alan Swinger wrote: 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 _._,_._,_ -- Richard Knoppow Los Angeles WB6KBL SKCC 19998
Anthony W. DePrato All Messages By This Member #30455 No they were for drift . used to keep the vfo section warm to cut down drift check the manual. Dampp-Chaser's were used in some gear . 73 Tony WA4JQS toggle quoted message Show quoted text At 01:54 PM 7/1/2024 -0700, you wrote: That thing was probably a Dampp-Chaser (with two P's). They were used in some receivers and in other equipment to keep moisture out.

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