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 Post subject: Re: Westinghouse model 801 grandfather clock radio.
PostPosted: Apr Wed 08, 2020 6:08 pm 
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spsquires wrote:
It was the 14300 brown and white resistor between cathode of tube 80 and screen grid of tube 235 IF . Also does bypass cap 4423 caps all go to chassis ground?


That is a pretty good description of which resistor. One minor but important detail, though. The transformer is not an IF transformer, it is an RF transformer, aka a Radio Frequency transformer.

You can tell the difference between RF and IF transformers by their location in the circuit.

An IF transformer will be to the right of the Mixer/First Detector No.3 tube in the schematic
An RF transformer will be in-between the RF Amp No. 1 tube. and the Oscillator Tube No.2 in the schematic for this radio. You will generally see this in most other radio schematics as well.

Now that you have the shorted resistor cleared up, you should see closer to normal voltages on the various tubes. Like I said a few posts ago, sometimes the problems we create while trying to fix a radio can be a real challenge.

Keep at it.

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 Post subject: Re: Westinghouse model 801 grandfather clock radio.
PostPosted: Apr Wed 08, 2020 7:25 pm 
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Got the caps done and radio working with just a little bit of interference but when I ground the radio it goes away. The voltages are 10 percent high all across the board.


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 Post subject: Re: Westinghouse model 801 grandfather clock radio.
PostPosted: Apr Wed 08, 2020 7:36 pm 
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Voltages are not a worry, that could be due to your incoming line voltage being a little high. Not sure but maybe that radio doesnt like to be grounded out, stopping the oscillator or something.

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 Post subject: Re: Westinghouse model 801 grandfather clock radio.
PostPosted: Apr Wed 08, 2020 7:59 pm 
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Sorry you may have misunderstood what I meant, the interference goes away after it is grounded.


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 Post subject: Re: Westinghouse model 801 grandfather clock radio.
PostPosted: Apr Thu 09, 2020 12:28 am 
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Yeah i did misunderstand . Sounds like you have it figured out

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 Post subject: Re: Westinghouse model 801 grandfather clock radio.
PostPosted: Apr Thu 09, 2020 3:14 pm 
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That shows a shielded transformer. They bleed charge to the chassis. I always fit a 3 wire cable, which grounds the chassis & gets rid of that charge.

Marc


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 Post subject: Re: Westinghouse model 801 grandfather clock radio.
PostPosted: Apr Thu 09, 2020 4:40 pm 
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So what you are saying is you install a wire cord and attach ground to ground terminal.


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 Post subject: Re: Westinghouse model 801 grandfather clock radio.
PostPosted: Apr Fri 10, 2020 12:23 am 
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If grounding the chassis stopped the carry, on then a permanent ground is a logical step.

Do note: that the circuit shows the primary of the antenna to be floating above ground (isolated). Therefore finding an improvement in reception by grounding it, as was intended, would not be unusual.

N.B. Antenna ground and chassis utility ground are not the same on this set as noted: But that, with a teeny bit of removable wire, grounded chassis to antenna Earth terminal will solve that. One always considers a grounded chassis (where possible: EG. Transformer set) to be intrinsically safer and more in line with regulations here, and due to the behaviour of shielded transformers: Desirable.

Marc


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 Post subject: Re: Westinghouse model 801 grandfather clock radio.
PostPosted: Apr Fri 10, 2020 12:47 am 
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Hi Marc I am not sure I understand what you mean?


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 Post subject: Re: Westinghouse model 801 grandfather clock radio.
PostPosted: Apr Fri 10, 2020 1:15 am 
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You grounded the set the noise went away.

I suggested fitting a permanent Utility ground via the supply cable, mainly because of the transformer type.

But, did you ground that set via the sets Earth terminal, or the chassis?

These are different entities: The sets Earth terminal does not ground the chassis (or to it) according to the way its presented on the schematic. The Primary of the Antenna Coil is isolated from the chassis; So will work best grounded. Earthing / grounding the chassis will not earth the antenna coil. That coil needs a separate earth, or tying to an earthed chassis to be effective.

Marc


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 Post subject: Re: Westinghouse model 801 grandfather clock radio.
PostPosted: Apr Fri 10, 2020 1:26 am 
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I attached a cut cord with only the ground terminal left on it to the ground screw next to antenna screw and plugged it in to the ground part of the receptacle.


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 Post subject: Re: Westinghouse model 801 grandfather clock radio.
PostPosted: Apr Fri 10, 2020 5:47 am 
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OK! So if it is wired per schematic; You only grounded the antenna coil.

Based on that positive outcome, if it were mine, I would fit a proper grounded utility cable with its 3 pin plug and tie its ground wire to chassis per regulations & connect the earth terminal near the antenna terminal to chassis.

Marc


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 Post subject: Re: Westinghouse model 801 grandfather clock radio.
PostPosted: Apr Fri 10, 2020 1:38 pm 
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The schematic specifies an external ground connection for the antenna primary. This is based on the basic principle that the incoming signal in the antenna is referenced to the local ground plane, which is often several feet below the surface.
Using the building ground is sometimes "OK", but is usually noisier than using a direct, dedicated, connection to the dirt. The common traditional advice was to use a cold water pipe. Obviously, that assumes metal piping. Next best might be a ground wire directly to the ground rod at the electric utility service entrance.

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 Post subject: Re: Westinghouse model 801 grandfather clock radio.
PostPosted: Apr Fri 10, 2020 1:57 pm 
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The electrical code here has 4 ground rods in the ground connected to panel box. So why would ground terminal at receptacle not work good?


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 Post subject: Re: Westinghouse model 801 grandfather clock radio.
PostPosted: Apr Fri 10, 2020 2:05 pm 
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spsquires wrote:
The electrical code here has 4 ground rods in the ground connected to panel box. So why would ground terminal at receptacle not work good?

common-mode noise......anything plugged into the electric circuits can put a noise current into the ground wire. That in turn develops a voltage that gets added to the signal coming in from the antenna.

"grounding" a radio to the outlet ground is often "good enough"---if in doubt, try other options----eg a wire direct to the service entrance, or to a dedicated ground rod.

The universal rule: "If it works, it's OK"

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 Post subject: Re: Westinghouse model 801 grandfather clock radio.
PostPosted: Apr Sat 11, 2020 12:26 am 
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The grounding here is quiet & most of it is is in water. I lost the very best one when I moved house. I twas attached to a bore casing it went down 120 feet into water. The workshop /office does have a separate ground for the antennas, but more so for tying the long wire antennas to ground to dissipate lightning.

My biggest issue is the Utility aerials introducing RF via the mains and they are filtered to get rid of it as it does sneak into sets.

Why I suggested the chassis earth has been made clear and does "clean" the chassis. I have on some sets measured a static charge from the transformer shields of several hundred volts (240V supply). Why I suggested a fly lead to the antenna earth is that it is easy to remove should that be unsuccessful. I can see noisy a earthing, or the entire system, in a densely populated area.

So far, from what was written, the Utility ground worked on that terminal & that's the important bit.

Marc


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 Post subject: Re: Westinghouse model 801 grandfather clock radio.
PostPosted: Apr Tue 21, 2020 12:14 am 
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Please lock , radio done and working.


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 Post subject: Re: Westinghouse model 801 grandfather clock radio.
PostPosted: Apr Tue 21, 2020 2:17 am 
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Normally, one does not lock a thread just because its finished. One normally locks it if its going to hell in a handbasket, or someone is being naughty.

Marc


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