[Hallicrafters] Hallicrafter S-77

[Walt Cates]

CORRECTION::: The 77 uses an house power electrical gnd buss that is not  connected to chassis gnd (at least it should not be). The white wire connects to this buss and not the chassis. The green wire may be omitted if you have up to code bonding between your antenna system and house power. If not it will connect to the chassis gnd (antenna/signal gnd). 

Best Regards, Walt Cates, WD0GOF
 
 Life is nothing but a short preAfterLife condition.
 
> From: cateswa at msn.com
> To: hallicrafters at mailman.qth.net
> Date: Tue, 5 Aug 2014 13:25:45 -0500
> Subject: Re: [Hallicrafters] Hallicrafter S-77
> 
> 
> 
> 
> There may be several versions of the S-77,,, I don't know. But the manual I have does not have a fuse and the neutral side of the line is switched to gnd. The schematic # is 190354.
>  
> If you are going to use a three wire cord and plug then first determine how your 77 was built. If it has no fuse and the neutral side of the line is switched to gnd then::: I would rewire S7 into the lead from C58 (leave C58 on the unswitched side of the fuse and switch) to pin 4 of the accessory plug and install a fuse holder in series with S7. Then white to chassis, black to fuse and green to receiver gnd.  If you have a full code bonding system between your house power and your antenna system then you can forgo the green wire and connect the receiver gnd to your antenna signal gnd. More on house power and antenna system bonding at http://arvideonews.com/hrn/HRN_Episode_0015.html. If your receiver is built to the 190354 schematic there is a 270K in parallel with a .05uf between the receiver gnd and the chassis gnd. The filaments and DC voltage supplies all use the chassis as gnd as a return. If your 77 is not built to the 190354 schematic then you will need to search for do
>  cumentation that matches your rig. Or try to figure out what has been done to the rig by a previous owner. 
> 
> 
> Best Regards, Walt Cates, WD0GOF
>  
>  Life is nothing but a short preAfterLife condition.
>  
> > Date: Tue, 5 Aug 2014 08:22:39 -0700
> > From: k9sth at sbcglobal.net
> > To: radiomanL at verizon.net; hallicrafters at mailman.qth.net
> > Subject: Re: [Hallicrafters] Hallicrafter S-77
> > 
> > It is possible to replace a 2-wire line cord with a 3-wire line cord in metal cased AC/DC receivers.  Also, a fuse should be added to comply with NFPA NEC (National Electrical Code).  A 3-wire cord should help with the hum problem and, much more important, get the metal cabinet at true ground potential.
> > 
> > As indicated on the schematic, there is a "ground buss" which keeps the AC power basically from the chassis.  The only connection between the AC line cord and the actual chassis is through a 270K resistor and a 0.05 mfd capacitor.
> > 
> > The AC line connections need to be modified when the 3-wire cord is added.  Connect the 3-wire cord as follows:
> > 
> > Black wire:  Through an added fuse to the off / on switch.
> > 
> > White wire:  Directly to the ground buss in the receiver.
> > 
> > Green wire:  Directly to the chassis.
> > 
> > For additional safety, I would replace the 270K (R-37) resistor and the capacitor in parrallel 0.05 at 600-volts (C-59) with a 0.047 at 600-volts, or better.
> > 
> > If the manual on the S-77 is needed, one can be downloaded from BAMA at
> > 
> > http://bama.edebris.com/manuals/hallicra/s77/
> > 
> > 
> > The manual is in DJVU format.  If a DJVU reader is needed, do a "Google" on "WinDjView" and that will take you to the reader, for free, which is, in my opinion, the best DJVU reader around.
> > 
> > Glen, K9STH
> > 
> > 
> > On Monday, August 4, 2014 3:53 PM, radiomanL <radiomanL at verizon.net> wrote:
> 
>  		 	   		  
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