High impedance rivets
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The worst example of high impedance rivets that I have seen was in a Gonset G-63 receiver.? I could not successfully align it once the caps were replaced until all of the tube socket ground rings were soldered to the chassis.? Once this was done, the receiver worked quite well. Currently working on a Zenith L600 Transoceanic replacing all paper and electrolytic caps, what a PITA!? Perhaps I did go a bit overboard by removing all connections to the four section filter capacitor which is buried under layers of other components.? I pity the poor girls who did the initial assembly!? Thankfully, the modern caps are physically much smaller so now there is lots of room under the chassis. Anyway, four of the five tube sockets are hard wired from the center tie point of the tube socket to the chassis.? This is unusual as most manufactures trusted the tube socket rivets so they didn't bother to do this hardwiring to the chassis.? No components use this tube socket connection in the TO so I am not sure why they did this in the first place.?? Regards, Jim Logic: Method used to arrive at the wrong conclusion, with confidence.? Murphy
On Sunday, May 4, 2025 at 02:31:29 AM CDT, haywireman via groups.io <haywireman@...> wrote:
Yes!? I have even wondered if soldering socket ground terminals to the chassis is enough to ensure good performance.? Solder is not the perfect conductor, and does not have the best strength or immunity to fracturing over time.? I have read several times that it is a "best practice" to wire every point directly to a common ground return on the chassis, but have never seen it done in practice, except maybe in some Collins equipment. John
On Saturday, May 3, 2025 at 10:40:58 AM CDT, Jim Whartenby via groups.io <old_radio@...> wrote:
Chassis grounds that use rivets is an ongoing problem.? Whenever there is a weird problem, like an alignment issue, I routinely solder the tube socket ground terminals and other ground tie points to the chassis as a first effort to resolve the problem.? This saves a lot of troubleshooting time and is good excuse to keep that old American Beauty 100 watt soldering iron in the toolbox. Jim Logic: Method used to arrive at the wrong conclusion, with confidence.? Murphy
On Friday, May 2, 2025 at 04:51:11 PM CDT, waltcates via groups.io <cateswa@...> wrote:
I have seen center post to ground as high as 150 ohms. It only takes 3 to 5 ohms to start causing problems with speed and weight. It has the biggest effect on the timing capacitors.
Walt Cates, WD0GOF
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A majority of acceptance is not proof of correctness.
From: [email protected] <[email protected]> on behalf of Floyd - K8AC via groups.io <floydsense@...>
Sent: Friday, May 2, 2025 2:41 PM To: [email protected] <[email protected]> Subject: Re: [HallicraftersRadios] HA-1 T.O. Keyer ?
Very good, Walt.? Glad to see you point out the problem with the tube socket grounds.? Years ago my HA-1 became erratic - code elements missing or the wrong length.? It took me many days before I discovered a faulty ground at a tube socket - it looked
perfect but must have had a high resistance.??
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73, Floyd - K8AC
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Jim - I re=capped a Zenith Transoceanic model 8G005 from the 1940s.? There were a couple paper caps I could not get to without disassembling a bunch of stuff and figured the risk was not worth it.? This was compounded by the wiring insulation was brittle and would crack and fall apart if moved!? That one has a whole bunch of new silicone insulated wire in it!
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Your observation about the rivets makes me wonder if that might have been the cause of some of my problems in the past...
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73,
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Justin B.
KI5GKD ?
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Jim Whartenby