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Removing/Reinstalling Complex Modules - Would This Work??




 
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January 26, 2022, 07:01:01 PM *
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Author Topic: Removing/Reinstalling Complex Modules - Would This Work??  (Read 236 times)
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KW4H
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« on: January 14, 2022, 11:51:59 AM »

The boat anchor I'm working on (HQ-180A) has a rather large wafer switch module covering an area of the radio that I will probably need to get to.  This means that the module will need to temporarily come out of the radio.  The module is held in with four screws that are simple to remove -- however, there are a number of wires that connect to the switch array from the IF section below that will have to be dealt with.  With many radios (such as the National NC-125) it's possible to "reverse manufacture" a switch array like this by pulling it out one section at a time -- the way it was obviously built.  The Hammarlund isn't so easy and appears to have been built in the factory by shrinking employees down to about a quarter-inch tall and inserting them -- and tiny soldering irons -- into the chassis.  I've been trying to figure out how Hammarlund did it.

Anyway, I've been circling around this problem for a day or two and trying to come up with a plan of attack.  One thought that's crossed my mind is to snip the wires at their mid-points and install insulated spade-lug quick disconnects.  Re-installing the switch array would still be tricky, but not involve soldering.  

Has anyone tried such an approach and found that it worked?  I'm curious if using such splices could negatively affect IF performance, even if crimped properly.

73 - Steve, KW4H
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WA2SQQ
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« Reply #1 on: January 14, 2022, 04:47:14 PM »

Lots of closeup detailed photos,
Iím watching this close since my 180 may need this. Fortunately I have a spare 180 carcass!
Has your 180 had much silver mica damage?
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KW4H
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« Reply #2 on: January 14, 2022, 04:59:32 PM »

Lots of closeup detailed photos,
Iím watching this close since my 180 may need this. Fortunately I have a spare 180 carcass!
Has your 180 had much silver mica damage?

Haven't identified any silver mica damage as of yet.  And the radio does generally work and is overall very clean, but the alignment needs to be touched up.  The upper band is awful in the sensitivity area, but the rest seems OK.  Right now I'm chasing down a totally annoying S-Meter bug -- I'll post the latest in a few minutes over in the main thread.  Depending on what else I find -- and some issues do appear to possibly be swimming around under that wafer switch bank -- I might have to pull the switch.  If I do, I'll check every component.  As much as I love the HQ-180A -- the positioning of that switch is, in my opinion anyway, a design train wreck.  But it is what it is.  For now I'm avoiding having to pull the thing out, but am preparing just in case.

Unless there's good reasons to the contrary, I believe the wire-cutting and use of spade-lug quick disconnects is the way to go.  Soldering around on these old wafer switches can end badly.  However, I would solder the spade lugs to the wires as well as crimp -- crimping alone is often unreliable.

73 - Steve, KW4H
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KD6VXI
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« Reply #3 on: January 14, 2022, 05:13:17 PM »

It was probably built as a prefabbed part.  IE:  The switch and wires where mounted, then each wire was pulled through to where it needed to be....  And the lengths where probably already trimmed, stripped and tinned.

As to crimping.  There is absolutely nothing wrong with crimping.  It is the only method in aerospace.  Solder is not allowed as it makes wire brittle.

Problem is, most hams don't have a proper 3 or 4 way crimper to do the correct job leading to crap installs.  But once you've used a quality 4 way crimper, you will leave soldering to where it's needed. I'm lucky, my new job has proper crimping tools for 28 gauge to 250MCM.  It helps tremendously.

If you where local, I'd offer to do some crimps up for ya. Unfortunately, I bet I'm a fair bit of distance away.

--Shane
WP2ASS / ex KD6VXI
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KW4H
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« Reply #4 on: January 14, 2022, 05:56:54 PM »

It was probably built as a prefabbed part.  IE:  The switch and wires where mounted, then each wire was pulled through to where it needed to be....  And the lengths where probably already trimmed, stripped and tinned.

As to crimping.  There is absolutely nothing wrong with crimping.  It is the only method in aerospace.  Solder is not allowed as it makes wire brittle.

Problem is, most hams don't have a proper 3 or 4 way crimper to do the correct job leading to crap installs.  But once you've used a quality 4 way crimper, you will leave soldering to where it's needed. I'm lucky, my new job has proper crimping tools for 28 gauge to 250MCM.  It helps tremendously.

If you where local, I'd offer to do some crimps up for ya. Unfortunately, I bet I'm a fair bit of distance away.

--Shane
WP2ASS / ex KD6VXI

Outstanding point about crimping -- I checked the tool collection and I do have a 4-way hydraulic crimper, but the dies are for larger wire sizes.  Could have sworn I had one for smaller sizes -- will have to check around some more.  If not, it would be an excellent "gift" to myself -- you can never have too many tools!  And there's lots of uses for crimping wires.
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w9jsw
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« Reply #5 on: January 15, 2022, 06:29:47 AM »

please post a quality example of a hand held crimper if you find one that does not require a mortgage.
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KW4H
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« Reply #6 on: January 15, 2022, 08:34:18 AM »

please post a quality example of a hand held crimper if you find one that does not require a mortgage.

My personal favorite -- and the one I have -- is made in the USA by a company called TEMCO.  Model number TH0006.  It's good for 12 gauge up to 2/0 (which makes it unusable for crimping small connectors).  However, I think it's a good example of a high-quality product that's not overly-expensive.  It runs about $130 on their website. Last year I built a pretty good sized solar generator and made the mistake of buying a cheaper hydraulic crimper off of Amazon.  The crimps were horrible because the dies were poorly made and not precisely the size they should have been.  I was crimping a lot of lugs onto 1/0 wire.

TEMCO doesn't have a crimper for smaller gauges.  But by comparison I'd expect to pay no more than $100 for something that would do the job with wire sizes smaller than 12 gauge.  

There are professional crimpers out there that cost a small fortune.  Those are extra heavy-duty, high precision tools designed to be used day-in and day-out on job sites by electricians and engineers.  In my opinion, the lower cost crimpers that are still made in the USA do a perfectly fine job for us hobbyists who only need crimpers once in a while, but want a good crimp when we do.

Oh, and another lesson I learned (the hard way) is to only use lugs made in the USA.  They can be bought online from electrical dealers.  The junk made in China and some other places is absolutely horrible -- they're frequently made of cheap metals, way too soft, and sometimes have conductivity issues.  I won't even buy foreign-made wire anymore -- Remington Industries makes excellent hook-up wire for restoration work.

Steve, KW4H


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