Call Search
     

New to Ham Radio?
My Profile

Community
Articles
Forums
News
Reviews
Friends Remembered
Strays
Survey Question

Operating
Contesting
DX Cluster Spots
Propagation

Resources
Calendar
Classifieds
Ham Exams
Ham Links
List Archives
News Articles
Product Reviews
QSL Managers

Site Info
eHam Help (FAQ)
Support the site
The eHam Team
Advertising Info
Vision Statement
About eHam.net

   Home   Help Search  
Pages: [1] 2 Next   Go Down
  Print  
Author Topic: Changing power cord question??  (Read 4584 times)
WB4SNU
Member

Posts: 78




Ignore
« on: August 18, 2012, 05:05:14 PM »

I was given a Hallicrafters HT 32B and I want to change the power cord. It is brittle and is a 2 wire cord.
I know this is old hat stuff but I don't know if I went to a 3 wire cord, would it make a difference in the circuits operating correctly since everything goes to chassis ground with the 2 wire cord. With the 3 wire cord, I can make sure when wiring it back that the hot is going to the right place.

I tried searching on this but couldn't find anything about this.

Thanks
Richard
Logged

Digital and CW spoken here.
W9GB
Member

Posts: 2648




Ignore
« Reply #1 on: August 18, 2012, 07:36:54 PM »

Quote from: WB4SNU
I was given a Hallicrafters HT 32B and I want to change the power cord. It is brittle and is a 2 wire cord.
I know this is old hat stuff, but I don't know if I went to a 3 wire cord, would it make a difference in the circuits operating correctly since everything goes to chassis ground with the 2 wire cord. With the 3 wire cord, I can make sure when wiring it back that the hot is going to the right place.
Richard,

The Hallicrafters HT-32A was manufactured, here in Chicago, from 1960-1964.  This 19 tube AM/SSB/CW transmitter matched the SX-115 Receiver.  This transmitter sold for $725.00 USD, in that era (50 years later that is easily equivalent to a premium Japanese mfg. radio at > $3,000 USD).

The 1960s was the last decade for extensive usage of NEMA 1 (2-wire, non-polarized, without safety ground) AC power plugs connectors for metalic chassis AC equipment.  
By the 1970s, after National Electrical Code of 1965 and 1970 were adopted, NEMA 5 (2-wire with safety ground) for 120 VAC power plugs and outlets was adopted in North America.
http://en.wikipedia.org/wiki/NEMA_connector

I am confused with the lack of clarity, in your specific question.
Do you know how to properly (and correctly) change an AC line cordage for this radio?
http://www.hometips.com/diy-how-to/electrical-cord-replace.html

We're you ever properly instructed?  High school shop, Military training, Boy Scouts Electric badge, 4-H Electric program, Community College, Apprentice for licensed electriian, Self-instruction home repair/improvement courses or books?

A NEMA 5-15P connctor and properly sized cordage can be installed on this transmitter.
You are also permitted to restore/repair the HT-32A to the NEMA 1-15P plug (polarized plug) and new replacement cordage.
SAFETY was the reason for Electrical Code changes (adopting AC safety ground).... My cousin was a couple years older than you in 1955 .... he was Electrocuted due to improperly wired welder at a motor bike shop.  Safety Grounding, had it existed, would have saved his life.

This can be performed, so as to look like factory install -- with patience, common electrical tools, AND proper training.

Do you a specific question or concern on how to properly connect 3-wire cordage to the HT-32B ??
The GREEN (Safety Ground) wire from the new cordage would need to be attached securely to transmitter's metal chassis.  The new cordage often requires a new strain relief (Heyco Industries).  I normally purchase replacement cordage with molded AC plug from McMaster-Carr.
One standard method is to solder or crimp a ring terminal or ring solder lug and place this with a star washer under an existing fastener (machine screw), that can not be removed accidentally by consumer.

BTW, when I do his type of repair --- I also CHANGE / update the safety capacitors that are located at these same attachment points for the AC Line cordage.
Just Radios, Mouser, Digi-Key, and McMaster-Carr carry these parts.
http://www.justradios.com/safetytips.html

« Last Edit: August 18, 2012, 08:14:17 PM by W9GB » Logged
WB4SNU
Member

Posts: 78




Ignore
« Reply #2 on: August 19, 2012, 03:54:34 AM »

Thanks Gregory for the info
A little background-- Retired electrician, ham since mid 60's, restored a few radios( recently a Hammarlund 100C) and build QRP things.
I only asked this since I have never replaced a power cord on a radio because I have read in the past that people had problems with some radios when they went from 2 wire to 3 wire cords.
I know the transformer isolates the power and all grounds go back to the chassis.
When I picked it up, the power cord was handed to me by hand not attached. It is so brittle that I needed to replace it.
I can wire it back with just the 2 wires but I thought I would make it a little safer with the ground to chassis hookup also.
Looking at the schematic, I can't see a problem with the circuits if I attach the ground to chassis but I have never went through a Hallicrafters radio either.

Also the 750v leads to the  rectifier tube were disconnected and I need to figure out why they were

I thank you for the reply. I am going to restore this one but I needed to ask this because I am starting from the start with safety in mind.

By the way, I have been shocked more times than I want to remember. Shocked

Thanks
Richard


Logged

Digital and CW spoken here.
W9GB
Member

Posts: 2648




Ignore
« Reply #3 on: August 19, 2012, 07:57:03 AM »

R -

Thanks for background ... So this is easy work for you.  :-)
Reactivating older radios
http://www.w9wze.net/df.php?dn=Tips/Reactivating_Old_Rigs.wp

HT-32 Restorations
http://www.amwindow.org/tech/htm/ht32resto.htm

http://www.antiqueradios.com/forums/viewtopic.php?t=148395

Quote from: WB4SNU
I only asked this since I have never replaced a power cord on a radio because I have read in the past that people had problems with some radios when they went from 2 wire to 3 wire cords.
The radios of this era normally had a Ground screw for the owner to attach to an earth ground or conductive water pipe. (advised in Owner's Manual)

The All-American Five Radios (Five vacuum tubes; filaments wires in series to 117 VAC Main; NO isolation transformer -- sold as consumer AC/DC radios from 1935-1965 -- can have problems IF not properly re-wired for 3-wire cordage.  The HT-32B is a transmitter with AC transformer.
http://en.wikipedia.org/wiki/All_American_Five
How All American Five worked
http://www.angelfire.com/electronic/funwithtubes/AA5-1.html

Quote from: WB4SNU
Also the 750v leads to the  rectifier tube were disconnected and I need to figure out why they were
LOOK for earlier (previous) changes/modifications that used Solid-State 1,000 V diodes instead of the vacuum tube rectifiers.  This is a common change by some technicians.
« Last Edit: August 19, 2012, 08:19:33 AM by W9GB » Logged
WB4SNU
Member

Posts: 78




Ignore
« Reply #4 on: August 19, 2012, 08:35:24 AM »

Hey again Gregory
Back when I was working, I seem to have had time to do all I wanted and needed but now that retired I can't find enough time in the day to do all I want too.
I have ordered from JustRadios before and I think it is time to restock my cabinet with some more stuff. This radio is in such good physical shape, I think it will be a good one to restore.
I am not sure yet why the trans. leads were taken off the rectifier but I want to start from the start to make it good and safe. I don't see any other mods. that would have been done yet.
I haven't applied power yet until I get the power end straightened out first.
The fellow that had it, I don't think, had any idea of what he was trying to do.
It looked like he had bypassed the fuse for some reason???

I have a variac and will apply power when that time comes. For now, until the line to ground cap comes, I'll just clean and test the tubes and make it shine.
I'll check with the local Radio Shack and see if they have the rated cap first since it is local, but I doubt they will have that.
I'll report back when I get it to power up and then see what I have then to deal with.

Thanks for all the leads and info.

Richard
Logged

Digital and CW spoken here.
W9GB
Member

Posts: 2648




Ignore
« Reply #5 on: August 19, 2012, 08:43:57 AM »

Quote
I'll check with the local Radio Shack and see if they have the rated capacitor first since it is local, but I doubt they will have that.
Very unlikely.

Radio Shack stopped carrying HV components, when they stopped carrying vacuum tubes and batteries in 1980s.  
Today, it is a mobile/cellular phone retail store ... future bankruptcy would not surprise me (too many retail mistakes).

Hallicrafters HT-32B manual
http://jptronics.org/radios/Hallicrafters/manuals.html

Radio / Boatanchor restorers use the Electronics distributors (Internet/Mail-order), a few surviving radio/TV shops, and better/larger hamfests for parts these days.
http://antiqueradio.org/parts.htm

There is a separate hobby for Antique Radio Retorers (1920s to 1960s).
http://antiqueradio.org/communications.htm

http://antiqueradio.org/FirstStepsInRestoration.htm
« Last Edit: August 19, 2012, 08:55:43 AM by W9GB » Logged
WB4SNU
Member

Posts: 78




Ignore
« Reply #6 on: August 19, 2012, 09:35:04 AM »

Hey Gregory
Thanks for the links. I downloaded the schematic first thing when I got it home. The other links are going to be looked at also.

Thanks
Richard
Logged

Digital and CW spoken here.
N8CMQ
Member

Posts: 386




Ignore
« Reply #7 on: August 23, 2012, 07:11:19 AM »

I am using Allied Elect. for my replacement parts. You can set up an account online and order easily.
Good luck on your restoration!
Logged
WB4SPT
Member

Posts: 160




Ignore
« Reply #8 on: August 23, 2012, 02:05:37 PM »

One last item.  UL specifically forbids soldered bonding wires.  So, please crimp properly that connection.  The idea being, in a fire or severe overload, the solder won't melt and allow the wire to be pulled from the terminal. 
Logged
W7GIF
Member

Posts: 126




Ignore
« Reply #9 on: August 23, 2012, 08:21:15 PM »

This radio is in such good physical shape, I think it will be a good one to restore.
I am not sure yet why the trans. leads were taken off the rectifier but I want to start from the start to make it good and safe. I don't see any other mods. that would have been done yet.
I haven't applied power yet until I get the power end straightened out first.
The fellow that had it, I don't think, had any idea of what he was trying to do.
It looked like he had bypassed the fuse for some reason???

I have a variac and will apply power when that time comes. For now, until the line to ground cap comes, I'll just clean and test the tubes and make it shine.
I'll check with the local Radio Shack and see if they have the rated cap first since it is local, but I doubt they will have that.
I'll report back when I get it to power up and then see what I have then to deal with.

Thanks for all the leads and info.

Richard
Richard,
I think I have an original manual for your HT-32B, and if I can find it, it's yours. Regarding the caps, yeah, radio shack no longer carries hv caps. Don't know if there are any FRY's Electronics in your area, but here in Phoenix they do have hv caps.

Check your "messages" folder. I'll let you know if/when I find the HT-32B manual.

Allen
Logged
WB4SNU
Member

Posts: 78




Ignore
« Reply #10 on: August 24, 2012, 02:34:40 AM »

Thanks Allen
I could use a good manual. The one I downloaded is fair but not very good after printing out.
Let me know if you find it and I'll compensate you for it.

Thanks
Richard
Logged

Digital and CW spoken here.
WB6DGN
Member

Posts: 619




Ignore
« Reply #11 on: August 26, 2012, 01:25:55 PM »

Quote
One last item.  UL specifically forbids soldered bonding wires.  So, please crimp properly that connection.  The idea being, in a fire or severe overload, the solder won't melt and allow the wire to be pulled from the terminal. 

Soldering terminal connections on aircraft wiring is also prohibited.  The reason is that, once a stranded wire is tinned, it becomes like a solid conductor, that is, brittle and subject to fatigue breakage.  I suspect that this is the issue with bonding wiring as well.
Tom
Logged
W9GB
Member

Posts: 2648




Ignore
« Reply #12 on: August 26, 2012, 01:40:13 PM »

Quote
I could use a good manual. The one I downloaded is fair but not very good after printing out.

Huh?? I just opened the HT-32A manual on my iPad, and the scan is excellent (300 to 600 dpi).
http://jptronics.org/radios/Hallicrafters/manuals.html

I could work on it, from this file alone -- clear markings for voltage readings, etc.
Logged
WB4SNU
Member

Posts: 78




Ignore
« Reply #13 on: August 26, 2012, 02:04:36 PM »

Thanks
I had all ready found that one. Works good here.

Thanks
Richard
Logged

Digital and CW spoken here.
W7GIF
Member

Posts: 126




Ignore
« Reply #14 on: August 26, 2012, 08:15:24 PM »

Thanks Allen
I could use a good manual. The one I downloaded is fair but not very good after printing out.
Let me know if you find it and I'll compensate you for it.

Thanks
Richard
Sorry to disappoint you Richard. Searched my library today, and have only the HT-33A manual......not the HT-32B. So much for "recollection".....
Allen
Logged
Pages: [1] 2 Next   Go Up
  Print  
 
Jump to:  

Powered by MySQL Powered by PHP Powered by SMF 1.1.11 | SMF © 2006-2009, Simple Machines LLC Valid XHTML 1.0! Valid CSS!