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QMX 1n4007 diodes
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I needed to replace one of the 1n4007 diodes in my QMX (I cut the lead for an experiment) so I went looking for a replacement. None of the 1n4007 diodes at Mouser have the small diameter leads like the ones from QRP Labs. They are all about .7mm diameter where the QRPLabs diodes are more like .3mm. I ended up ordering Vishay diodes with the fat leads.
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I had cleared the holes with the solder sucker but the leads still did not fit so I used some PCB drill bits to clear the holes and finally got the diode in there. Hopefully the via barrel is still intact. I am waiting for some caps to put it back together and try it.
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Any discussion about these diodes? My experience is that 1N400x diodes all had fat leads.
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Thanks,
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Tony
AD0VC |
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Tony,
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The QMX series of radios uses a 6-layer PCB. Making the drilling hole larger could cause gaps in the internal layers. It would be better to use a thin lead and solder the fat lead above the board. Look at the board trace pictures and the schematics to verify that the connections are still there.
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73
Evan
AC9TU |
开云体育
Nothing fancy on these connections. Top layer and bottom layer traces only. I just checked with the meter and all is well. My question really was about the diodes. Where do you get 1n4007 diodes with .3mm leads?
Tony
AD0VC
From: [email protected] <[email protected]> on behalf of Evan Hand via groups.io <elhandjr@...>
Sent: Thursday, May 22, 2025 7:59 PM To: [email protected] <[email protected]> Subject: Re: [QRPLabs] QMX 1n4007 diodes ?
Tony,
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The QMX series of radios uses a 6-layer PCB. Making the drilling hole larger could cause gaps in the internal layers. It would be better to use a thin lead and solder the fat lead above the board. Look at the board trace pictures and the schematics to
verify that the connections are still there.
?
73
Evan
AC9TU
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Hi Tony I just measured one of the 1N4007 diodes from the kits, the wire diameter is 0.4mm. According to the PCB CAD program (I just checked) the footprint for these diodes specifies a 0.8mm drill size. So the holes ought to fit 0.7mm wire too.? 73 Hans G0UPL On Fri, May 23, 2025 at 5:07?AM mux_folder2001 via <canthony15=[email protected]> wrote:
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开云体育
Thanks Hans. The hole diameter is good to know. I used my old dial micrometer, which is calibrated in inches, to measure a diode from the kit and then did a bad mental conversion to metric. Still, much smaller than a regular 1N400x. When you clear the holes
with a solder sucker, it leaves some solder still in the hole which has to be cleared out to get the fat diode leads in there.
73,
Tony
AD0VC
From: [email protected] <[email protected]> on behalf of Hans Summers via groups.io <hans.summers@...>
Sent: Friday, May 23, 2025 2:56 AM To: [email protected] <[email protected]> Subject: Re: [QRPLabs] QMX 1n4007 diodes ?
Hi Tony
I just measured one of the 1N4007 diodes from the kits, the wire diameter is 0.4mm. According to the PCB CAD program (I just checked) the footprint for these diodes specifies a 0.8mm drill size. So the holes ought to fit 0.7mm wire too.?
73 Hans G0UPL
On Fri, May 23, 2025 at 5:07?AM mux_folder2001 via
<canthony15=[email protected]> wrote:
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I've successfully cleared holes with a hand pin vise and an assortment of really teeny drill bits. Start with an obviously too small bit and work up in size until the component just fits. Go slow, clear the swarf often.?
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Successfully opened up many in QDXs, QMXs and 50Watt amps.? Lately though, I bought some Chip Quick brand desolder braid. Just needed some more and decided to try theirs. Fabulous stuff! No extra flux needed and it really pulls solder away. I flow extra fresh solder on the hole in question and then apply the braid and iron quickly. Tug the long end up a bit and hold while it flows up the braid. Works a treat as the Brits say.? Greg KI4NVX?
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Thanks Greg. I will try that next time. I have tried to use low temp solder to help clear the ground connections but it did not work. I managed to use a push-pin and a very hot iron to open those up.
Tony
AD0VC
From: [email protected] <[email protected]> on behalf of Greg McCain via groups.io <gamccain50@...>
Sent: Friday, May 23, 2025 6:53 AM To: [email protected] <[email protected]> Subject: Re: [QRPLabs] QMX 1n4007 diodes ?
I've successfully cleared holes with a hand pin vise and an assortment of really teeny drill bits. Start with an obviously too small bit and work up in size until the component just fits. Go slow, clear the swarf often.?
Successfully opened up many in QDXs, QMXs and 50Watt amps.?
Lately though, I bought some Chip Quick brand desolder braid. Just needed some more and decided to try theirs. Fabulous stuff! No extra flux needed and it really pulls solder away. I flow extra fresh solder on the hole in question and then apply the braid
and iron quickly. Tug the long end up a bit and hold while it flows up the braid. Works a treat as the Brits say.?
Greg KI4NVX?
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I'm with Evan here.?
I'd never drill out a through-hole so I could insert a new diode.?
Nor would I use a push pin to try to (partially) clean out the hole.
Just clip the old diode or BS170 or whatever out and solder the new one to the stubs.
There is no need for the leads of the new part to go through the board.
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Heating the board again and again to clean it with a solder sucker or solder wick is a fools errand.
The heat will compromise how well the pads adhere to the board.
If the pads get lifted off you then have?to figure out how to re-attach the broken traces.
Been there done that many times over a 45 yr career designing circuit boards.
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The above is especially true for a multilayer board with internal traces and planes like the QMX.
A drill could easily cause shorts between internal layers near the hole.
Some parts such as BGA's (not found on the QMX) have pins (or balls) underneath the part,
and a single broken traces means throwing away a high value board since it can't be repaired
with a wire across the surface.? When dealing with RF or high speed clocks,? a patch wire
across the surface can behave much differently than the engineered trace through the board.
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ChipQuik would work well enough when removing connectors and switches that must be
replaced with correct physical alignment,? or a heavy part that might break free due to vibration
unless it is properly mounted.? For a diode it's a waste of perfectly good ChipQuick.
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Jerry, KE7ER
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On Thu, May 22, 2025 at 06:59 PM, Evan Hand wrote:
The QMX series of radios uses a 6-layer PCB. Making the drilling hole larger could cause gaps in the internal layers. It would be better to use a thin lead and solder the fat lead above the board. Look at the board trace pictures and the schematics to verify that the connections are still there. |
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On Thu, May 22, 2025 at 10:03 PM, Curt wb8yyy wrote:
Whether the via is needed depends upon which or both have connections.?Drilling is not an acceptable rework method for boards with plated-thru holes.? This is a 6-layer board with internal layers you should never go any where near it with a drill bit lest you ruin the board. 73, Don N2VGU
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Hans says the boards are specced for a 0.8mm drill size. With a 0.7mm lead that only leaves 0.1mm, or 4 thou in real units, for the through-hole plating (equivalent to just 2 thou on each side of the hole). I would not be surprised if, in trying to get the new lead through the hole, you damage the plating. So my choice would be to leave the remains of the old lead in place and solder the new component on the top. And if you've already removed the old lead I'd solder a new piece of wire through the hole, either a bit of component lead or a left-over bit of magnet wire from the coil winding. In the case of this diode, which is apparently not connected to the inner layers, I'd make very sure that it is soldered soundly on both the top and bottom of the board. Regards Keith, G0GNL |
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Hi Hans,
As a teenager, I worked as a metal plater and etcher for two printed circuit shops. At some point during my employ, they tasked me with every operation in PCB manufacture. The PCB shops that I worked for, generally drilled their holes with the closest sized drills in their tool crib, equal to, or larger than the drill sizes listed in the customer's tool list. In addition, the first hole drilled by a given drill is measurably larger than the last hole drilled by that drill... wear happens. Manufacturers are motivated to use a drill for just as long as it will drill effectively, and the hole diameter meets the customer's tolerance band... some will use them for quite a bit longer... Where some major contention invariably happens is plated-through holes. When a hole is plated, the as-drilled size is reduced by the thickness of the hole's plating, which is typically 0.1-0.2mm, to create the finished hole size. Most manufacturers expect you to give them the as-drilled size in your tool list, but others expect to be given the finished hole size. Manufacturers will generally reveal the necessary hole size information somewhere in their contract's boiler plate. Customers will generally ignore that boiler plate, imagining that things will work out OK by default. I know that you may already know all of this, but I choose to mention it anyway for two reasons: 1) general knowledge, and 2) because many of the holes in my QMX+ PCB seem about a plating allowance too tight... while others (connectors, switches) are grossly big, and yet still ill-fitting. I can only guess at the whys and wherefores.... -Chuck Harris, WA3UQV On Fri, 23 May 2025 11:56:32 +0300 "Hans Summers via groups.io" <hans.summers@...> wrote: Hi Tony |
Donald S Brant Jr
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