PA Transistors Maintenance in K2
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PA Transistors Maintenance in K2
 
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I vaguely remember reading somewhere that after some number of hours of operation – maybe 50 – the hardware holding Q7 and Q8 onto the heat sink should be tightened, I presume to maintain good heat conduction from the tabs to the sink. But I can’t find that instruction in the manual now. Anyone know where I might have gotten that notion, or did I just make it up?
Thanks, Ted, KN1CBR ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] |
Re: PA Transistors Maintenance in K2
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On page 51 of the Rev 2 KPA100 manual, I found the following:
------------------ IMPORTANT: The hardware holding the RF power transistors in place will loosen slightly during initial use. After 5-10 hours of normal operation at 50 watts or more, remove the KPA100 assembly and its shield, then re-tighten the mounting hardware for Q1/Q2 approximately 1/8 turn. ------------------- I didn't look to see if this was in other versions of the manual; this was the first place I looked. 73, Victor, 4X6GP Rehovot, Israel Formerly K2VCO http://www.qsl.net/k2vco/ On 28 Oct 2017 06:15, Dauer, Edward wrote: > I vaguely remember reading somewhere that after some number of hours of operation – maybe 50 – the hardware holding Q7 and Q8 onto the heat sink should be tightened, I presume to maintain good heat conduction from the tabs to the sink. But I can’t find that instruction in the manual now. Anyone know where I might have gotten that notion, or did I just make it up? > > Thanks, > > Ted, KN1CBR ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] |
Re: PA Transistors Maintenance in K2
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In reply to this post by Edward A. Dauer
Ted,
Not Q7 and Q8 in the base K2, but for the KPA100, yes tightening the screws for Q1 and Q2 should be done after 5 to 10 hours of operation at greater then 50 watts. 73, Don W3FPR On 10/27/2017 11:15 PM, Dauer, Edward wrote: > I vaguely remember reading somewhere that after some number of hours of operation – maybe 50 – the hardware holding Q7 and Q8 onto the heat sink should be tightened, I presume to maintain good heat conduction from the tabs to the sink. But I can’t find that instruction in the manual now. Anyone know where I might have gotten that notion, or did I just make it up? ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] |
Re: PA Transistors Maintenance in K2
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In reply to this post by Edward A. Dauer
A nice tip which I use when looking for anything in any sort of .pdf manual, Elecraft included as I have accumulated quite a number of them over time is to use the search feature on the .pdf reader. Ctrl+f on WIndows and cmd+f on Mac and type what I'm looking for. The index and contents tables are good, but obviously can't have everything in them, so I use the find feature a lot.
Hope this helps. Regards, Cameron - AF7DK/GM7LQR ________________________________ From: [hidden email] <[hidden email]> on behalf of Dauer, Edward <[hidden email]> Sent: Friday, October 27, 2017 8:15 PM To: [hidden email] Subject: [Elecraft] PA Transistors Maintenance in K2 I vaguely remember reading somewhere that after some number of hours of operation – maybe 50 – the hardware holding Q7 and Q8 onto the heat sink should be tightened, I presume to maintain good heat conduction from the tabs to the sink. But I can’t find that instruction in the manual now. Anyone know where I might have gotten that notion, or did I just make it up? Thanks, Ted, KN1CBR ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] |
Re: PA Transistors Maintenance in K2
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Ted,
If the people at Elecraft have done their job and mounted the transistor properly with the correct torque on the mounting hardware procedure, no additional maintainance is required. I have been in the industry for a LONG time . Three things to remember in the mounting of any RF or high power device. Flat surfaces, minimual mating gu, and required torque. Lack of any of these will kill a device if not correct. I have never required retorqueing parts, with one exception. In 000 copper wire terminals, the copper does relax and needs to be retorqued to achieve a gas tight seal connection, but that is in industrial application. Small RF devices only need the initial torque to be correct. Mel, K6KBE From: Cameron Francey <[hidden email]> To: "Dauer, Edward" <[hidden email]>; "[hidden email]" <[hidden email]> Sent: Saturday, October 28, 2017 12:10 PM Subject: Re: [Elecraft] PA Transistors Maintenance in K2 A nice tip which I use when looking for anything in any sort of .pdf manual, Elecraft included as I have accumulated quite a number of them over time is to use the search feature on the .pdf reader. Ctrl+f on WIndows and cmd+f on Mac and type what I'm looking for. The index and contents tables are good, but obviously can't have everything in them, so I use the find feature a lot. Hope this helps. Regards, Cameron - AF7DK/GM7LQR ________________________________ From: [hidden email] <[hidden email]> on behalf of Dauer, Edward <[hidden email]> Sent: Friday, October 27, 2017 8:15 PM To: [hidden email] Subject: [Elecraft] PA Transistors Maintenance in K2 I vaguely remember reading somewhere that after some number of hours of operation – maybe 50 – the hardware holding Q7 and Q8 onto the heat sink should be tightened, I presume to maintain good heat conduction from the tabs to the sink. But I can’t find that instruction in the manual now. Anyone know where I might have gotten that notion, or did I just make it up? Thanks, Ted, KN1CBR ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] |
Re: PA Transistors Maintenance in K2
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Mel,
That is NOT true for the KPA100 power transistors - and it is not because of initial torquing. The thermal pads take both time and heat to fully conform to the heatsink and any irregularities in the transistor surface. BTW, with the KPA100, Elecraft has "done their job" when the parts are put into the box. This is not sold as an assembled item - the builder must assemble it. I tighten those screws on every KPA100 that I service. I am amazed at the number I find loose. 73, Don W3FPR On 10/28/2017 3:24 PM, Mel Farrer via Elecraft wrote: > Ted, > If the people at Elecraft have done their job and mounted the transistor properly with the correct torque on the mounting hardware procedure, no additional maintainance is required. I have been in the industry for a LONG time . Three things to remember in the mounting of any RF or high power device. Flat surfaces, minimual mating gu, and required torque. Lack of any of these will kill a device if not correct. I have never required retorqueing parts, with one exception. In 000 copper wire terminals, the copper does relax and needs to be retorqued to achieve a gas tight seal connection, but that is in industrial application. Small RF devices only need the initial torque to be correct. ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] |
Re: PA Transistors Maintenance in K2
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In reply to this post by Elecraft mailing list
K2s are not factory assembled.
73, Ross N4RP On 10/28/2017 03:24 PM, Mel Farrer via Elecraft wrote: > Ted, > If the people at Elecraft have done their job and mounted the transistor properly with the correct torque on the mounting hardware procedure, no additional maintainance is required. I have been in the industry for a LONG time . Three things to remember in the mounting of any RF or high power device. Flat surfaces, minimual mating gu, and required torque. Lack of any of these will kill a device if not correct. I have never required retorqueing parts, with one exception. In 000 copper wire terminals, the copper does relax and needs to be retorqued to achieve a gas tight seal connection, but that is in industrial application. Small RF devices only need the initial torque to be correct. > > Mel, K6KBE > > From: Cameron Francey <[hidden email]> > To: "Dauer, Edward" <[hidden email]>; "[hidden email]" <[hidden email]> > Sent: Saturday, October 28, 2017 12:10 PM > Subject: Re: [Elecraft] PA Transistors Maintenance in K2 > > A nice tip which I use when looking for anything in any sort of .pdf manual, Elecraft included as I have accumulated quite a number of them over time is to use the search feature on the .pdf reader. Ctrl+f on WIndows and cmd+f on Mac and type what I'm looking for. The index and contents tables are good, but obviously can't have everything in them, so I use the find feature a lot. > > > Hope this helps. > > > Regards, Cameron - AF7DK/GM7LQR > > > ________________________________ > From: [hidden email] <[hidden email]> on behalf of Dauer, Edward <[hidden email]> > Sent: Friday, October 27, 2017 8:15 PM > To: [hidden email] > Subject: [Elecraft] PA Transistors Maintenance in K2 > > I vaguely remember reading somewhere that after some number of hours of operation – maybe 50 – the hardware holding Q7 and Q8 onto the heat sink should be tightened, I presume to maintain good heat conduction from the tabs to the sink. But I can’t find that instruction in the manual now. Anyone know where I might have gotten that notion, or did I just make it up? > > Thanks, > > Ted, KN1CBR > > > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:[hidden email] > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > Message delivered to [hidden email] > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:[hidden email] > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > Message delivered to [hidden email] > > > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:[hidden email] > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > Message delivered to [hidden email] -- FCC Section 97.313(a) “At all times, an amateur station must use the minimum transmitter power necessary to carry out the desired communications.” ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] |
Re: PA Transistors Maintenance in K2
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In reply to this post by Edward A. Dauer
Don,
I ran my KXPA100 mobile for 5,000 miles to-Seattle and back to AK this spring. Is there any advise for maint for extended mobile use? 73, Ed - KL7UW. making 9,600 mile R/T summer of 2018. From: Don Wilhelm <[hidden email]> To: "Dauer, Edward" <[hidden email]>, "[hidden email]" <[hidden email]> Subject: Re: [Elecraft] PA Transistors Maintenance in K2 Message-ID: <[hidden email]> Content-Type: text/plain; charset=utf-8; format=flowed Ted, Not Q7 and Q8 in the base K2, but for the KPA100, yes tightening the screws for Q1 and Q2 should be done after 5 to 10 hours of operation at greater then 50 watts. 73, Don W3FPR 73, Ed - KL7UW http://www.kl7uw.com Dubus-NA Business mail: [hidden email] ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] |
Re: PA Transistors Maintenance in K2
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Ed,
I was speaking of the KPA100 amp for the K2. I don't think the KXPA100 needs any maintenance. 73, Don W3FPR On 10/28/2017 7:52 PM, Edward R Cole wrote: > Don, > > I ran my KXPA100 mobile for 5,000 miles to-Seattle and back to AK this > spring. Is there any advise for maint for extended mobile use? ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] |
Re: PA Transistors Maintenance in K2
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In reply to this post by Cameron Francey
The .pdf reader search function is an excellent way to find
where the off-sheet connections go when reading the Elecraft schematics. 73 Bill AE6JV On 10/28/17 at 12:08 PM, [hidden email] (Cameron Francey) wrote: >A nice tip which I use when looking for anything in any sort of >.pdf manual, Elecraft included as I have accumulated quite a >number of them over time is to use the search feature on the >.pdf reader. Ctrl+f on WIndows and cmd+f on Mac and type what >I'm looking for. The index and contents tables are good, but >obviously can't have everything in them, so I use the find >feature a lot. ------------------------------------------------------------------------- Bill Frantz | When it comes to the world | Periwinkle (408)356-8506 | around us, is there any choice | 16345 Englewood Ave www.pwpconsult.com | but to explore? - Lisa Randall | Los Gatos, CA 95032 ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] |
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In reply to this post by Cameron Francey
Also, you can search the pdf schematics- very convenient when tracing
through circuits spanning multiple sheets. 73, Drew AF2Z On 10/28/17 15:08, Cameron Francey wrote: > A nice tip which I use when looking for anything in any sort of .pdf manual, Elecraft included as I have accumulated quite a number of them over time is to use the search feature on the .pdf reader. Ctrl+f on WIndows and cmd+f on Mac and type what I'm looking for. The index and contents tables are good, but obviously can't have everything in them, so I use the find feature a lot. > > > Hope this helps. > > > Regards, Cameron - AF7DK/GM7LQR > > > ________________________________ > From: [hidden email] <[hidden email]> on behalf of Dauer, Edward <[hidden email]> > Sent: Friday, October 27, 2017 8:15 PM > To: [hidden email] > Subject: [Elecraft] PA Transistors Maintenance in K2 > > I vaguely remember reading somewhere that after some number of hours of operation – maybe 50 – the hardware holding Q7 and Q8 onto the heat sink should be tightened, I presume to maintain good heat conduction from the tabs to the sink. But I can’t find that instruction in the manual now. Anyone know where I might have gotten that notion, or did I just make it up? > > Thanks, > > Ted, KN1CBR > > > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:[hidden email] > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > Message delivered to [hidden email] > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:[hidden email] > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > Message delivered to [hidden email] > ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] |
Re: PA Transistors Maintenance in K2
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In reply to this post by Elecraft mailing list
As far as I can tell, no torque settings are given for any of the
fasteners, wouldn't it be an idea to provide those, for people who do have suitable tools. Generally there are just warnings not to over-tighten. On 28/10/17 20:24, Mel Farrer wrote: > If the people at Elecraft have done their job and mounted the transistor properly with the correct torque on the mounting hardware procedure, no additional maintainance is required. -- David Woolley K2 06123 ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] |
Re: PA Transistors Maintenance in K2
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It is possible that an explicit torque has never been calculated. It is
not a particularly hard thing to do however. I do not have a K2, so I can't do it, but here's the idea: 1) Fastener size/type, material, thread spec: (e.g. 4-40 x ___ pan head, phillips, zinc coated, non-rated steel 2) What does fastener anchor in? (e.g. aluminum heat sink, what alloy aluminum, thickness of threaded area. 3) Thread spec... not JUST the #4, 40 tpi, but the rating for thread engagement. 4) Check the specs for the RF transistor.... package, et al. Docs may/should have a max torque spec for the package.... maybe... package material, etc. 5) # of fasteners... usually 1 maybe 2. There are tables that specify general torque specs for fasteners, threads in various materials, etc.... The idea is to take the lowest max value from the list. This becomes the MAX NTE. Then, use some analysis and judgement in what forces are to be imparted to the joint.... static tension, sheer, axial, radial, vibration, et al... Then in this instance consider the qualities of the mating surfaces.... are the flat? What is the run out? Are they smooth? To what grit spec are they smooth? There's a difference between flat and smooth. What is the interface material being used? Thermal pad? Insulating? Non-insulating? Initial thickness? Read the spec sheet for the thermal pad/compound. I suspect here that the RF package has an insulating thermal pad between it and the heatsink... It was probably spec'd to keep the RF package within its operating envelope under 90% of expected operating conditions... knowing Elecraft, probably even a higher spec, and maybe a little extra to cover the "cheater". Thermal pads and MANY top quality thermal compounds REQUIRE a curing period. If the package is held with a tension spring/fastener, there is usually no requirement/need to re-torque. IF it is JUST a screw and maybe a locknut, you NEED TO RETORQUE after a given number of thermal cycles.... The thermal interface material flows under heat and cools when not in use. Eventually it reaches an equilibrium. You torque the fastener JUST enough to hold the junction static at this point. I'm a freak, I would use a thermally conducting thread locking/anti-seize compound (I made one). I NEVER torque unlubricated fasteners.... ESPECIALLY steel to aluminum interfaces. The final torque for this application is likely in the relatively low inch-pound range.... just guessing. I have 2 inch-pound wrenches... 0-15, and 0-70. Most people don't.... Key... do NOT over-torque. Consider the lever length and force applied... 73, Clay, KY5G On 10/29/2017 8:03 AM, David Woolley wrote: > As far as I can tell, no torque settings are given for any of the > fasteners, wouldn't it be an idea to provide those, for people who do > have suitable tools. Generally there are just warnings not to > over-tighten. > > On 28/10/17 20:24, Mel Farrer wrote: >> If the people at Elecraft have done their job and mounted the >> transistor properly with the correct torque on the mounting hardware >> procedure, no additional maintainance is required. > > -- > David Woolley > K2 06123 Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] |
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Here is one reliable source for screw torque.
http://www.mgtd.ca/screw%20torque.htm Now, to get the proper torque tools and use them. 73 Bob, K4TAX On 10/29/2017 8:34 AM, Clay Autery wrote: > It is possible that an explicit torque has never been calculated. It > is not a particularly hard thing to do however. > > I do not have a K2, so I can't do it, but here's the idea: > > 1) Fastener size/type, material, thread spec: (e.g. 4-40 x ___ pan > head, phillips, zinc coated, non-rated steel > 2) What does fastener anchor in? (e.g. aluminum heat sink, what alloy > aluminum, thickness of threaded area. > 3) Thread spec... not JUST the #4, 40 tpi, but the rating for thread > engagement. > 4) Check the specs for the RF transistor.... package, et al. Docs > may/should have a max torque spec for the package.... maybe... package > material, etc. > 5) # of fasteners... usually 1 maybe 2. > > There are tables that specify general torque specs for fasteners, > threads in various materials, etc.... The idea is to take the lowest > max value from the list. This becomes the MAX NTE. > Then, use some analysis and judgement in what forces are to be > imparted to the joint.... static tension, sheer, axial, radial, > vibration, et al... > Then in this instance consider the qualities of the mating > surfaces.... are the flat? What is the run out? Are they smooth? To > what grit spec are they smooth? There's a difference between flat and > smooth. > What is the interface material being used? Thermal pad? Insulating? > Non-insulating? Initial thickness? Read the spec sheet for the thermal > pad/compound. > > I suspect here that the RF package has an insulating thermal pad > between it and the heatsink... It was probably spec'd to keep the RF > package within its operating envelope under 90% of expected operating > conditions... knowing Elecraft, probably even a higher spec, and maybe > a little extra to cover the "cheater". > > Thermal pads and MANY top quality thermal compounds REQUIRE a curing > period. If the package is held with a tension spring/fastener, there > is usually no requirement/need to re-torque. > > IF it is JUST a screw and maybe a locknut, you NEED TO RETORQUE after > a given number of thermal cycles.... The thermal interface material > flows under heat and cools when not in use. Eventually it reaches an > equilibrium. > You torque the fastener JUST enough to hold the junction static at > this point. I'm a freak, I would use a thermally conducting thread > locking/anti-seize compound (I made one). > I NEVER torque unlubricated fasteners.... ESPECIALLY steel to aluminum > interfaces. > > The final torque for this application is likely in the relatively low > inch-pound range.... just guessing. I have 2 inch-pound wrenches... > 0-15, and 0-70. Most people don't.... > > Key... do NOT over-torque. Consider the lever length and force > applied... > > 73, > Clay, KY5G > > > On 10/29/2017 8:03 AM, David Woolley wrote: >> As far as I can tell, no torque settings are given for any of the >> fasteners, wouldn't it be an idea to provide those, for people who do >> have suitable tools. Generally there are just warnings not to >> over-tighten. >> >> On 28/10/17 20:24, Mel Farrer wrote: >>> If the people at Elecraft have done their job and mounted the >>> transistor properly with the correct torque on the mounting hardware >>> procedure, no additional maintainance is required. >> >> -- >> David Woolley >> K2 06123 > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:[hidden email] > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > Message delivered to [hidden email] ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] |
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In reply to this post by Drew AF2Z
Single best tip I've learned all year from this reflector. And there
were many good ones. Eric KE6US On 10/29/2017 4:24 AM, Drew AF2Z wrote: > Also, you can search the pdf schematics- very convenient when tracing > through circuits spanning multiple sheets. > > 73, > Drew > AF2Z ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] |
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In reply to this post by Bob McGraw - K4TAX
Perhaps a bit big for electronics work, but I’ve become a big fan of the
Borka adjustable torque wrench for mounting optics. On Sunday, October 29, 2017, Bob McGraw K4TAX <[hidden email]> wrote: > Here is one reliable source for screw torque. > > http://www.mgtd.ca/screw%20torque.htm > > Now, to get the proper torque tools and use them. > > 73 > > Bob, K4TAX > > > > On 10/29/2017 8:34 AM, Clay Autery wrote: > >> It is possible that an explicit torque has never been calculated. It is >> not a particularly hard thing to do however. >> >> I do not have a K2, so I can't do it, but here's the idea: >> >> 1) Fastener size/type, material, thread spec: (e.g. 4-40 x ___ pan head, >> phillips, zinc coated, non-rated steel >> 2) What does fastener anchor in? (e.g. aluminum heat sink, what alloy >> aluminum, thickness of threaded area. >> 3) Thread spec... not JUST the #4, 40 tpi, but the rating for thread >> engagement. >> 4) Check the specs for the RF transistor.... package, et al. Docs >> may/should have a max torque spec for the package.... maybe... package >> material, etc. >> 5) # of fasteners... usually 1 maybe 2. >> >> There are tables that specify general torque specs for fasteners, threads >> in various materials, etc.... The idea is to take the lowest max value from >> the list. This becomes the MAX NTE. >> Then, use some analysis and judgement in what forces are to be imparted >> to the joint.... static tension, sheer, axial, radial, vibration, et al... >> Then in this instance consider the qualities of the mating surfaces.... >> are the flat? What is the run out? Are they smooth? To what grit spec are >> they smooth? There's a difference between flat and smooth. >> What is the interface material being used? Thermal pad? Insulating? >> Non-insulating? Initial thickness? Read the spec sheet for the thermal >> pad/compound. >> >> I suspect here that the RF package has an insulating thermal pad between >> it and the heatsink... It was probably spec'd to keep the RF package >> within its operating envelope under 90% of expected operating conditions... >> knowing Elecraft, probably even a higher spec, and maybe a little extra to >> cover the "cheater". >> >> Thermal pads and MANY top quality thermal compounds REQUIRE a curing >> period. If the package is held with a tension spring/fastener, there is >> usually no requirement/need to re-torque. >> >> IF it is JUST a screw and maybe a locknut, you NEED TO RETORQUE after a >> given number of thermal cycles.... The thermal interface material flows >> under heat and cools when not in use. Eventually it reaches an equilibrium. >> You torque the fastener JUST enough to hold the junction static at this >> point. I'm a freak, I would use a thermally conducting thread >> locking/anti-seize compound (I made one). >> I NEVER torque unlubricated fasteners.... ESPECIALLY steel to aluminum >> interfaces. >> >> The final torque for this application is likely in the relatively low >> inch-pound range.... just guessing. I have 2 inch-pound wrenches... 0-15, >> and 0-70. Most people don't.... >> >> Key... do NOT over-torque. Consider the lever length and force applied... >> >> 73, >> Clay, KY5G >> >> >> On 10/29/2017 8:03 AM, David Woolley wrote: >> >>> As far as I can tell, no torque settings are given for any of the >>> fasteners, wouldn't it be an idea to provide those, for people who do have >>> suitable tools. Generally there are just warnings not to over-tighten. >>> >>> On 28/10/17 20:24, Mel Farrer wrote: >>> >>>> If the people at Elecraft have done their job and mounted the >>>> transistor properly with the correct torque on the mounting hardware >>>> procedure, no additional maintainance is required. >>>> >>> >>> -- >>> David Woolley >>> K2 06123 >>> >> ______________________________________________________________ >> Elecraft mailing list >> Home: http://mailman.qth.net/mailman/listinfo/elecraft >> Help: http://mailman.qth.net/mmfaq.htm >> Post: mailto:[hidden email] >> >> This list hosted by: http://www.qsl.net >> Please help support this email list: http://www.qsl.net/donate.html >> Message delivered to [hidden email] >> > > > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:[hidden email] > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > Message delivered to [hidden email] -- Scott Small ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] |
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