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S-85: how are the RF amplifier tube (v1) and the MIX/OSC tube (v2) coupled in band1?

Emanuele Girlando All Messages By This Member #31899 Edited This topic raised in the "TRIMCAPs don't peak" thread. I think it's worth its own thread. Here it is. ? In the S-85 there is no obvious coupling between the RF amplifier tube (v1) and the MIX/OSC tube (v2) in band 1. The output of V1 seems to get lost in the R26/C29 couple. ? Someone argued that the signal path could go through the S1B wafers. Other argued that there is some other stray coupling in the circuit wiring. Someone noted that the S-40B has an identical circuit but it is equipped with an additional capacitor (C62), positioned just between the V1 output and the v2 input. The following picture sketches the S-85 circuit with the possible signal path and the phantom C62 highlighted. ? ? ? So I've made some measurements on my S-85. Using my 9640B sig-gen connected to the ANT A2 input via a RTMA dummy antenna (A1 shorted to GND), AM modulated at 30%, I got the following: Below the indicated value the signal gets lost in the noise. As you see I also made a test shorting R65 in the input circuit as someone argued that it could impact (as it does) the receiver sensitivity in the higher part of band 1. ? Thoughts? -- Emanuele (IU1KNR).
don Root All Messages By This Member #31901 Edited 开云体育 Emanuele ? Yes, I prefer to look at R26 and C29 as the plate load Impedance, so the V1 output voltage is developed thru it, and as you reiterated there is no V1-V2 obvious intended coupling in band 1, but the switch has inherent capacitance across the wafer and perhaps that is enough, as your tests seem to indicate. Any yes R65 is probably to reduce overload tendencies on the BCB. ? Recall that C62 began with the S-40A [not the same spot] , and perhaps the S-40? ? toggle quoted message Show quoted text From: [email protected] [mailto:[email protected]] On Behalf Of Emanuele Girlando via groups.io Sent: Wednesday, February 26, 2025 12:46 PM To: [email protected] Subject: [HallicraftersRadios] S-85: how are the RF amplifier tube (v1) and the MIX/OSC tube (v2) coupled in band1? ? This topic raised in the "TRIMCAPs don't peak" thread. I think it's worth its own thread. Here it is. ? In the S-85 there is no obvious coupling between the RF amplifier tube (v1) and the MIX/OSC tube (v2) in band 1. The output of V1 seems to get lost in the R26/C29 couple. ? Someone argued that the signal path could go through the S1B wafers. Other argued that there is some other stray coupling in the circuit wiring. Someone noted that the S-40B has an identical circuit but it is equipped with an additional capacitor (C62), positioned just between the V1 output and the v2 input. The following picture sketches the S-85 circuit with the possible signal path and the phantom C62 highlighted. ? ? ? So I've made some measurements on my S-85. Using my 9640B sig-gen connected to the ANT A2 input via a RTMA dummy antenna (A1 shorted to GND), AM modulated at 30%, I got the following: Below the indicated value the signal gets lost in the noise. As you see I also made a test shorting R65 in the input circuit as someone argued that it could impact (as it does) the receiver sensitivity in the higher part of band 1. ? Thoughts? -- Emanuele (IU1KNR). -- don??? va3drl
Maynard Wright All Messages By This Member #31903 Note that the S-40A uses an entirely different arrangement of coils and capacitors and has no equivalent to C62 in the S-40B. So why is the S-40B equipped with C62? Maybe switch S1B in the S-85 exhibits a higher capacitance between the two rotary segments than does S1B in the S-40B, making C62 unnecessary to achieve the desired coupling capacitance in the S-85. Although the parts numbers are the same, maybe Hallicrafters used a different switch vendor for the S-85. Knowing this would matter only if someone were restoring a receiver and expected a part number for one type to represent the same exact part for another type. And maybe that's the case. But I haven't thought about that until now. 73, Maynard W6PAP toggle quoted message Show quoted text On 2/26/25 13:05, don Root wrote: Emanuele Yes, I prefer to look at R26 and C29 as the plate load Impedance, so the V1 output voltage is developed thru it, and as you reiterated there is no V1-V2 obvious intended coupling in band 1, but the switch has inherent capacitance across the wafer and perhaps that is enough, as your tests seem to indicate. Any yes R65 is probably to reduce overload tendencies on the BCB. Recall that C62 began with the S-40A [not the same spot] , and perhaps the S-40? From:[email protected] [mailto:[email protected]] On Behalf Of Emanuele Girlando via groups.io Sent: Wednesday, February 26, 2025 12:46 PM To: [email protected] Subject: [HallicraftersRadios] S-85: how are the RF amplifier tube (v1) and the MIX/OSC tube (v2) coupled in band1? This topic raised in the "TRIMCAPs don't peak" thread. I think it's worth its own thread. Here it is. In the S-85 there is no obvious coupling between the RF amplifier tube (v1) and the MIX/OSC tube (v2) in band 1. The output of V1 seems to get lost in the R26/C29 couple. Someone argued that the signal path could go through the S1B wafers. Other argued that there is some other stray coupling in the circuit wiring. Someone noted that the S-40B has an identical circuit but it is equipped with an additional capacitor (C62), positioned just between the V1 output and the v2 input. The following picture sketches the S-85 circuit with the possible signal path and the phantom C62 highlighted. So I've made some measurements on my S-85. Using my 9640B sig-gen connected to the ANT A2 input via a RTMA dummy antenna (A1 shorted to GND), AM modulated at 30%, I got the following: Below the indicated value the signal gets lost in the noise. As you see I also made a test shorting R65 in the input circuit as someone argued that it could impact (as it does) the receiver sensitivity in the higher part of band 1. Thoughts? -- Emanuele (IU1KNR). <> -- don??? va3drl
don Root All Messages By This Member #31904 开云体育 Maynard on the S-40A,? C62 is ??in use on band 2 only but connects V1 and V2?? like in the B version …I think. We need somebody to LRC a sample switch. ? toggle quoted message Show quoted text From: [email protected] [mailto:[email protected]] On Behalf Of Maynard Wright via groups.io Sent: Thursday, February 27, 2025 11:16 AM To: [email protected] Subject: Re: [HallicraftersRadios] S-85: how are the RF amplifier tube (v1) and the MIX/OSC tube (v2) coupled in band1? ? Note that the S-40A uses an entirely different arrangement of coils and capacitors and has no equivalent to C62 in the S-40B. So why is the S-40B equipped with C62? Maybe switch S1B in the S-85 exhibits a higher capacitance between the two rotary segments than does S1B in the S-40B, making C62 unnecessary to achieve the desired coupling capacitance in the S-85. Although the parts numbers are the same, maybe Hallicrafters used a different switch vendor for the S-85. Knowing this would matter only if someone were restoring a receiver and expected a part number for one type to represent the same exact part for another type. And maybe that's the case. But I haven't thought about that until now. 73, Maynard W6PAP -- don??? va3drl
Maynard Wright All Messages By This Member #31905 Hi, Don, When I said that there is no C62 equivalent in the S-40A, I meant that there is no capacitor like C62 that is connected around the switching and resonant circuits so that it is completely independent of the setting of the bandswitch. 73, Maynard W6PAP toggle quoted message Show quoted text On 2/27/25 11:49, don Root wrote: Maynard on the S-40A,? C62 is ??in use on band 2 only but connects V1 and V2?? like in the B version …I think. We need somebody to LRC a sample switch. From:[email protected] [mailto:[email protected]] On Behalf Of Maynard Wright via groups.io Sent: Thursday, February 27, 2025 11:16 AM To: [email protected] Subject: Re: [HallicraftersRadios] S-85: how are the RF amplifier tube (v1) and the MIX/OSC tube (v2) coupled in band1? Note that the S-40A uses an entirely different arrangement of coils and capacitors and has no equivalent to C62 in the S-40B. So why is the S-40B equipped with C62? Maybe switch S1B in the S-85 exhibits a higher capacitance between the two rotary segments than does S1B in the S-40B, making C62 unnecessary to achieve the desired coupling capacitance in the S-85. Although the parts numbers are the same, maybe Hallicrafters used a different switch vendor for the S-85. Knowing this would matter only if someone were restoring a receiver and expected a part number for one type to represent the same exact part for another type. And maybe that's the case. But I haven't thought about that until now. 73, Maynard W6PAP -- don??? va3drl
Maynard Wright All Messages By This Member #31906 And my S-40A schematic is from Sam's Photofacts (via the Web) and it doesn't have C62 as in your schematic nor does it use independent designation of each component, but labels them with numbers referred to the table of components. So more than one component can have the same number. So I suspect that your schematic excerpt is from the S-40A Hallicrafters manual, which looks (in your excerpt) more like the S-40B and S-85 schematics I have from Hallicrafters manuals. But I don't have that manual. Since those two schematics don't agree, I wonder whether there was a revision during production of the S-40A. 73, Maynard W6PAP toggle quoted message Show quoted text On 2/27/25 12:38, Maynard Wright wrote: Hi, Don, When I said that there is no C62 equivalent in the S-40A, I meant that there is no capacitor like C62 that is connected around the switching and resonant circuits so that it is completely independent of the setting of the bandswitch. 73, Maynard W6PAP On 2/27/25 11:49, don Root wrote: Maynard on the S-40A,? C62 is ??in use on band 2 only but connects V1 and V2?? like in the B version …I think. We need somebody to LRC a sample switch. From:[email protected] [mailto:[email protected]] On Behalf Of Maynard Wright via groups.io Sent: Thursday, February 27, 2025 11:16 AM To: [email protected] Subject: Re: [HallicraftersRadios] S-85: how are the RF amplifier tube (v1) and the MIX/OSC tube (v2) coupled in band1? Note that the S-40A uses an entirely different arrangement of coils and capacitors and has no equivalent to C62 in the S-40B. So why is the S-40B equipped with C62? Maybe switch S1B in the S-85 exhibits a higher capacitance between the two rotary segments than does S1B in the S-40B, making C62 unnecessary to achieve the desired coupling capacitance in the S-85. Although the parts numbers are the same, maybe Hallicrafters used a different switch vendor for the S-85. Knowing this would matter only if someone were restoring a receiver and expected a part number for one type to represent the same exact part for another type. And maybe that's the case. But I haven't thought about that until now. 73, Maynard W6PAP -- don??? va3drl
don Root All Messages By This Member #31907 开云体育 Maynard, yes wording is tough.? “C62”? had been started..? then it moved ? To me it showed that it was thought to be needed? for? a simple coil, but not for a transformer? .. A version Then when the B came along? with two coils, they moved it ?a bit. toggle quoted message Show quoted text From: [email protected] [mailto:[email protected]] On Behalf Of Maynard Wright via groups.io Sent: Thursday, February 27, 2025 3:38 PM To: [email protected] Subject: Re: [HallicraftersRadios] S-85: how are the RF amplifier tube (v1) and the MIX/OSC tube (v2) coupled in band1? ? Hi, Don, When I said that there is no C62 equivalent in the S-40A, I meant that there is no capacitor like C62 that is connected around the switching and resonant circuits so that it is completely independent of the setting of the bandswitch. 73, Maynard W6PAP On 2/27/25 11:49, don Root wrote: Maynard on the S-40A,? C62 is ??in use on band 2 only but connects V1 and V2?? like in the B version …I think. We need somebody to LRC a sample switch. From:[email protected] [mailto:[email protected]] On Behalf Of Maynard Wright via groups.io Sent: Thursday, February 27, 2025 11:16 AM To: [email protected] Subject: Re: [HallicraftersRadios] S-85: how are the RF amplifier tube (v1) and the MIX/OSC tube (v2) coupled in band1? Note that the S-40A uses an entirely different arrangement of coils and capacitors and has no equivalent to C62 in the S-40B. So why is the S-40B equipped with C62? Maybe switch S1B in the S-85 exhibits a higher capacitance between the two rotary segments than does S1B in the S-40B, making C62 unnecessary to achieve the desired coupling capacitance in the S-85. Although the parts numbers are the same, maybe Hallicrafters used a different switch vendor for the S-85. Knowing this would matter only if someone were restoring a receiver and expected a part number for one type to represent the same exact part for another type. And maybe that's the case. But I haven't thought about that until now. 73, Maynard W6PAP -- don??? va3drl -- don??? va3drl
Jim Whartenby All Messages By This Member #31908 The S-40B Photofact Folder that I copied calls it C7 but it is still a 2.2 pF cap just as is C62.? Sam's has a format that they follow so their component designations are not the same as hallicrafters, especially after several hallicrafters S-40 revisions. See:?? Jim Logic: Method used to arrive at the wrong conclusion, with confidence.? Murphy On Thursday, February 27, 2025 at 02:52:05 PM CST, Maynard Wright via groups.io <m-wright@...> wrote: And my S-40A schematic is from Sam's Photofacts (via the Web) and it doesn't have C62 as in your schematic nor does it use independent designation of each component, but labels them with numbers referred to the table of components. So more than one component can have the same number. So I suspect that your schematic excerpt is from the S-40A Hallicrafters manual, which looks (in your excerpt) more like the S-40B and S-85 schematics I have from Hallicrafters manuals. But I don't have that manual. Since those two schematics don't agree, I wonder whether there was a revision during production of the S-40A. 73, Maynard W6PAP toggle quoted message Show quoted text On 2/27/25 12:38, Maynard Wright wrote: Hi, Don, When I said that there is no C62 equivalent in the S-40A, I meant that there is no capacitor like C62 that is connected around the switching and resonant circuits so that it is completely independent of the setting of the bandswitch. 73, Maynard W6PAP On 2/27/25 11:49, don Root wrote: Maynard on the S-40A,? C62 is ??in use on band 2 only but connects V1 and V2?? like in the B version …I think. We need somebody to LRC a sample switch. From:[email protected] [mailto:[email protected]] On Behalf Of Maynard Wright via groups.io Sent: Thursday, February 27, 2025 11:16 AM To: [email protected] Subject: Re: [HallicraftersRadios] S-85: how are the RF amplifier tube (v1) and the MIX/OSC tube (v2) coupled in band1? Note that the S-40A uses an entirely different arrangement of coils and capacitors and has no equivalent to C62 in the S-40B. So why is the S-40B equipped with C62? Maybe switch S1B in the S-85 exhibits a higher capacitance between the two rotary segments than does S1B in the S-40B, making C62 unnecessary to achieve the desired coupling capacitance in the S-85. Although the parts numbers are the same, maybe Hallicrafters used a different switch vendor for the S-85. Knowing this would matter only if someone were restoring a receiver and expected a part number for one type to represent the same exact part for another type. And maybe that's the case. But I haven't thought about that until now. 73, Maynard W6PAP -- don??? va3drl
don Root All Messages By This Member #31909 Edited 开云体育 Maynard FYI ??S-40 [no suffix]?? This seems to have no C62 and looks like “your” 40A at first glance? ..SO? maybe you have an early run manual of the “40A” ? ? FYI ??S-40A I was using= ??? ? Another thing, the bias/AVC line to V1 changed when going to the 40B, so it needed that C33? because L3 was not a transformer. ? ? toggle quoted message Show quoted text From: [email protected] [mailto:[email protected]] On Behalf Of Maynard Wright via groups.io Sent: Thursday, February 27, 2025 3:51 PM To: [email protected] Subject: Re: [HallicraftersRadios] S-85: how are the RF amplifier tube (v1) and the MIX/OSC tube (v2) coupled in band1? ? And my S-40A schematic is from Sam's Photofacts (via the Web) and it doesn't have C62 as in your schematic nor does it use independent designation of each component, but labels them with numbers referred to the table of components. So more than one component can have the same number. So I suspect that your schematic excerpt is from the S-40A Hallicrafters manual, which looks (in your excerpt) more like the S-40B and S-85 schematics I have from Hallicrafters manuals. But I don't have that manual. Since those two schematics don't agree, I wonder whether there was a revision during production of the S-40A. 73, Maynard W6PAP ? -- don??? va3drl
don Root All Messages By This Member #31910 开云体育 Hi Jim , and all; ?revising numbering ?makes it tough to compare things !!!! So the Halli C62 function remains? ?despite our communication inability. ? I guess that it one reason I often take a snip of what I? See on the drawing and circle it?? etc. ? toggle quoted message Show quoted text From: [email protected] [mailto:[email protected]] On Behalf Of Jim Whartenby via groups.io Sent: Thursday, February 27, 2025 5:14 PM To: [email protected] Subject: Re: [HallicraftersRadios] S-85: how are the RF amplifier tube (v1) and the MIX/OSC tube (v2) coupled in band1? ? The S-40B Photofact Folder that I copied calls it C7 but it is still a 2.2 pF cap just as is C62.? Sam's has a format that they follow so their component designations are not the same as hallicrafters, especially after several hallicrafters S-40 revisions. See:?? Jim ? ?? -- don??? va3drl
edward schumacher All Messages By This Member #31911 So new thread started on the same dead horse. how many weeks will this one run? On Thursday, February 27, 2025 at 04:09:43 PM CST, don Root <drootofallevil@...> wrote: Maynard, yes wording is tough.? “C62”? had been started..? then it moved ? To me it showed that it was thought to be needed? for? a simple coil, but not for a transformer? .. A version Then when the B came along? with two coils, they moved it ?a bit. toggle quoted message Show quoted text From: [email protected] [mailto:[email protected]] On Behalf Of Maynard Wright via groups.io Sent: Thursday, February 27, 2025 3:38 PM To: [email protected] Subject: Re: [HallicraftersRadios] S-85: how are the RF amplifier tube (v1) and the MIX/OSC tube (v2) coupled in band1? ? Hi, Don, When I said that there is no C62 equivalent in the S-40A, I meant that there is no capacitor like C62 that is connected around the switching and resonant circuits so that it is completely independent of the setting of the bandswitch. 73, Maynard W6PAP On 2/27/25 11:49, don Root wrote: Maynard on the S-40A,? C62 is ??in use on band 2 only but connects V1 and V2?? like in the B version …I think. We need somebody to LRC a sample switch. From:[email protected] [mailto:[email protected]] On Behalf Of Maynard Wright via groups.io Sent: Thursday, February 27, 2025 11:16 AM To: [email protected] Subject: Re: [HallicraftersRadios] S-85: how are the RF amplifier tube (v1) and the MIX/OSC tube (v2) coupled in band1? Note that the S-40A uses an entirely different arrangement of coils and capacitors and has no equivalent to C62 in the S-40B. So why is the S-40B equipped with C62? Maybe switch S1B in the S-85 exhibits a higher capacitance between the two rotary segments than does S1B in the S-40B, making C62 unnecessary to achieve the desired coupling capacitance in the S-85. Although the parts numbers are the same, maybe Hallicrafters used a different switch vendor for the S-85. Knowing this would matter only if someone were restoring a receiver and expected a part number for one type to represent the same exact part for another type. And maybe that's the case. But I haven't thought about that until now. 73, Maynard W6PAP -- don??? va3drl -- don??? va3drl
don Root All Messages By This Member #31912 Edited 开云体育 So new thread started on the same dead horse. how many weeks will this one run?? ?52 ? ? HOPE IT BEGINS TO WORK -- don??? va3drl
Maynard Wright All Messages By This Member #31913 Well, you and I seem to differ on the value of that thread. I learned several things from folks here who have a wealth of knowledge. 73, Maynard W6PAP toggle quoted message Show quoted text On 2/27/25 16:28, edward schumacher wrote: So new thread started on the same dead horse. how many weeks will this one run? On Thursday, February 27, 2025 at 04:09:43 PM CST, don Root <drootofallevil@...> wrote: Maynard, yes wording is tough.? “C62”? had been started..? then it moved To me it showed that it was thought to be needed? for? a simple coil, but not for a transformer? .. A version Then when the B came along? with two coils, they moved it ?a bit. From:[email protected] [mailto:[email protected]] On Behalf Of Maynard Wright via groups.io Sent: Thursday, February 27, 2025 3:38 PM To: [email protected] Subject: Re: [HallicraftersRadios] S-85: how are the RF amplifier tube (v1) and the MIX/OSC tube (v2) coupled in band1? Hi, Don, When I said that there is no C62 equivalent in the S-40A, I meant that there is no capacitor like C62 that is connected around the switching and resonant circuits so that it is completely independent of the setting of the bandswitch. 73, Maynard W6PAP On 2/27/25 11:49, don Root wrote: Maynard on the S-40A,? C62 is ??in use on band 2 only but connects V1 and V2?? like in the B version …I think. We need somebody to LRC a sample switch. From:[email protected] [mailto:[email protected]] On Behalf Of Maynard Wright via groups.io Sent: Thursday, February 27, 2025 11:16 AM To: [email protected] Subject: Re: [HallicraftersRadios] S-85: how are the RF amplifier tube (v1) and the MIX/OSC tube (v2) coupled in band1? Note that the S-40A uses an entirely different arrangement of coils and capacitors and has no equivalent to C62 in the S-40B. So why is the S-40B equipped with C62? Maybe switch S1B in the S-85 exhibits a higher capacitance between the two rotary segments than does S1B in the S-40B, making C62 unnecessary to achieve the desired coupling capacitance in the S-85. Although the parts numbers are the same, maybe Hallicrafters used a different switch vendor for the S-85. Knowing this would matter only if someone were restoring a receiver and expected a part number for one type to represent the same exact part for another type. And maybe that's the case. But I haven't thought about that until now. 73, Maynard W6PAP -- don??? va3drl -- don??? va3drl

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