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Hallicrafter HT-37 xmtr and S-76 recvr Need new homes and TLC
开云体育? I just updated the following 2 ads on QTH and thought that ops on this server could be the Better caretaker: ? ? SEE ATTACHED PIX: ? A S-76 RECEIVER on top at 46lbs with the right most large microvolt/S-meter glass removed The mechanicals of the meter/indicator are shot. Cosmetically pretty beat; bottom front case rust, but no internal penetration. Was capable of 538khz thru 34 mhz in its day. Will need work!
Nice cosmetics.... ALL original components….clean and very repairable. All dial tuning/bandspread controls work smoothly as well as other pots, swts, toggles, buttons ? ALL offers considered and replied to.?? TU and 73 ? ? STAY SAFE AND STAY WELL! ? Respectfully, NJ DOH Licensed EMT;? PHTLS, AMLS, PHPEC Millenium EMS ARC N.E. BioMedical Services ARC N.E. Disaster Cycle Services ? |
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Re: HA-1 T.O. Keyer socket gnds
开云体育On 5/4/25 12:34 PM, Paul
Christensen via groups.io wrote:
On a positive note, I replaced the AF amps in my Drake R-4B and R-4C receivers.? The goal was to get hum/buzz down to zero with the AF control wide open.? With a screwdriver connected to the AF amp’s ground lead, I wiped across the chassis in search of the lowest hum/buzz level.? I found several points that met this criteria.? Once found, a hole was drilled in the chassis and a solder lug added for the ground connection. ?At these points, AC heater ground current is minimal, sometimes cancelling altogether.? Thanks Paul.? That screw driver wipe technique is something I will need to remember.? I also do a fair amount of old stereo restoration and your technique will sure come in useful. 73 Don N9OO |
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Re: High impedance rivets
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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High impedance rivets
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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Re: HA-1 T.O. Keyer socket gnds
开云体育We sometimes forget that a chassis is often a high-current AC conductor, sometimes carrying several amps of tube heater current.? To Don’s comment, bonding to a single common chassis point often reduces or eliminates induced hum and buzz.? ? Someone mentioned using balanced heaters and a hum control balancing pot.? That’s excellent advice, but during production, manufacturers would typically wire the heater bus first, then overlay additional wiring like laced cable harnesses.? In many transceivers with dense wiring practices, it’s a real challenge to replace heater wiring with a twisted pair without disrupting components and existing wire runs, even if attempting an overlay.? I once tried to balance a Collins KWM-2A’s heather string but gave up: a point was reached where collateral damage started to occur owing to under-chassis packaging density.? ? On a positive note, I replaced the AF amps in my Drake R-4B and R-4C receivers.? The goal was to get hum/buzz down to zero with the AF control wide open.? With a screwdriver connected to the AF amp’s ground lead, I wiped across the chassis in search of the lowest hum/buzz level.? I found several points that met this criteria.? Once found, a hole was drilled in the chassis and a solder lug added for the ground connection. ?At these points, AC heater ground current is minimal, sometimes cancelling altogether.? ? Paul, W9AC ? ? From: [email protected] <[email protected]>
On Behalf Of Don Buska - The Radio Lab Works
Sent: Sunday, May 4, 2025 8:26 AM To: [email protected] Subject: Re: [HallicraftersRadios] HA-1 T.O. Keyer socket gnds ? On 5/4/25 2:31 AM, haywireman via groups.io wrote:
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Thomas K. Lanieri
Don Buska - The Radio Lab Works
Jim Whartenby
Paul Christensen