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 Post subject: Zenith TO power supply
PostPosted: Nov Thu 08, 2018 4:31 am 
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Location: saint clair shores, michigan
What is the amperage of the power supply for this radio? Can it be unregulated? How can this radio be dated?

Mike


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 Post subject: Re: Zenith TO power supply
PostPosted: Nov Thu 08, 2018 6:59 am 
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1968rt wrote:
What is the amperage of the power supply for this radio? Can it be unregulated? How can this radio be dated?

Mike


12V, around 20 mA, ideally regulated. But the current draw is so low that you can usually use a 9v unregulated supply and it will float up under the low load to 12V. I wouldn't suggest a 12V unregulated supply because even a pretty small/low current supply will be more like 15V under the very light load.

By the way, beware the polarity of the power supply - the *shield* is positive, the *tip* is negative. That's backwards from most standard systems.

Brett


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 Post subject: Re: Zenith TO power supply
PostPosted: Nov Thu 08, 2018 1:41 pm 
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Quote:
how can this radio be dated?

https://www.radiomuseum.org/r/zenith_tr ... _3000.html

You should be able to find the model number or chassis number on the back of the chassis.

12 volts at 20 mA? That's only 240 mW......don't we need more than that just for the speaker?

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 Post subject: Re: Zenith TO power supply
PostPosted: Nov Thu 08, 2018 4:10 pm 
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Location: Mountains of Mourne. Ireland.
Image
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Greg.


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 Post subject: Re: Zenith TO power supply
PostPosted: Nov Thu 08, 2018 7:28 pm 
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Looking more reasonable this is.......

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 Post subject: Re: Zenith TO power supply
PostPosted: Nov Thu 08, 2018 7:40 pm 
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Do I have to use one of those unusual looking jacks?

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 Post subject: Re: Zenith TO power supply
PostPosted: Nov Thu 08, 2018 9:32 pm 
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$4.00 shipped. https://www.ebay.com/itm/Truetone-1-SPO ... 1#viTabs_0

positive tip.

Greg.

oh... I was never keen on this type of D.C. jack!
Best to keep the wall-wart switched off while inserting and removing.


Last edited by egg on Nov Thu 08, 2018 9:35 pm, edited 1 time in total.

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 Post subject: Re: Zenith TO power supply
PostPosted: Nov Thu 08, 2018 9:35 pm 
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1968rt wrote:
How can this radio be dated?


Soft lights, romantic music, and soothing words.


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 Post subject: Re: Zenith TO power supply
PostPosted: Nov Fri 09, 2018 12:47 am 
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Me... I would use a SONY 9V old-school AC Adapter.

Image

Sony also made 9V AC adapters with negative center polarity, be careful.


Others from the same family. Scroll-up!
viewtopic.php?p=2265195#p2265195

Do your research, as there were a couple of lemons.
https://www.universal-radio.com/catalog ... /2023.html

Greg.


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 Post subject: Re: Zenith TO power supply
PostPosted: Nov Fri 09, 2018 9:55 am 
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Yes, heed the warning about using a 9volt power supply. Most power supplies will give 300mA or more but because they are unregulated and the current drawn by your 3000-1 so low, about 25mA, the voltage may well float up to 15volts or more. Given that the two capacitors right across the 12volt input are only rated at 12volts they may well go pop on the higher voltage. I run my 3000-1 on a 9volt wall wart and it works perfectly well - and yes, you do need that small 'earphone' type plug with the negative input on the tip. As somebody else said - turn the power supply off before you insert the plug into the radio to avoid shorting the power input. You'll notice if you ever find one that the Zenith plug has a very long insulator so it doesn't short out as you plug it in.

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 Post subject: Re: Zenith TO power supply
PostPosted: Nov Fri 09, 2018 5:12 pm 
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Thanks to all for your quick replies. I have many (too many) warts in my spare parts inventory, including many with the earphone type jacks. What I was asking about was the unusual long center insulator. Is it a problem to use a jack that has the normal, almost invisible separation between the so called "tip" and "ring" (the names of which I understand come from phone equipment)? I can find a suitable volt/amp wart, but will a "regular" jack cause a short or open circuit? A "normal" jack looks like the tip might not even reach far enough into the female jack. Thanks again for the speedy and informative replies.

Mike

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 Post subject: Re: Zenith TO power supply
PostPosted: Nov Fri 09, 2018 5:55 pm 
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Location: Mountains of Mourne. Ireland.
Non invasive conversion...

Image

This metal panel-mount coax-style DC power jack accepts 5.5mm O.D.x2.1mm I.D. plugs.
Requires 7/16" mounting hole.

RadioShack on-line. $2.00

Greg.


oh... dozens of other sizes can be found at DigiKey or the likes.


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 Post subject: Re: Zenith TO power supply
PostPosted: Nov Fri 09, 2018 7:56 pm 
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Your question...
Quote:
What I was asking about was the unusual long center insulator. Is it a problem to use a jack that has the normal, almost invisible separation between the so called "tip" and "ring" (the names of which I understand come from phone equipment)? I can find a suitable volt/amp wart, but will a "regular" jack cause a short or open circuit? A "normal" jack looks like the tip might not even reach far enough into the female jack. Thanks again for the speedy and informative replies.


My reply posted before your question..... :)

Quote:
As somebody else said - turn the power supply off before you insert the plug into the radio to avoid shorting the power input. You'll notice if you ever find one that the Zenith plug has a very long insulator so it doesn't short out as you plug it in.

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Last edited by majoco on Nov Fri 09, 2018 8:16 pm, edited 1 time in total.

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 Post subject: Re: Zenith TO power supply
PostPosted: Nov Fri 09, 2018 8:14 pm 
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Here's a pic of the plug on my 9volt wall wart that I use on my 3000-1.
The diameter is 0.097" so slightly under one-tenth of an inch and the length from the face to the tip is 0.475" so just under a half-inch.
Attachment:
DSCF1385 sml.jpg
DSCF1385 sml.jpg [ 47.75 KiB | Viewed 292 times ]

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 Post subject: Re: Zenith TO power supply
PostPosted: Nov Sun 11, 2018 9:22 pm 
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To be perfectly honest, I never power any of my solid-state Zenith T-Os from the AC line, even though most of them are well capable of being so powered. I much prefer batteries, which after all conforms to their original design as portables. Battery power involves no risk at all (whether from power surges, lightening strikes or improper choice of a transformer), and given only moderate use these D-cells will literally last for years in a Zenith T-O (depending of course upon the quality of the batteries installed). The added advantages of battery power include: No possible RF interference from the incoming AC line, ready availability in case of a power outage, and obviously the ability to "carry it with you" as a portable whether traveling, working in the yard, sitting outside on the porch, working on a jobsite, etc.

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 Post subject: Re: Zenith TO power supply
PostPosted: Nov Mon 12, 2018 8:43 pm 
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Quote:
The added advantages of battery power include: No possible RF interference from the incoming AC line, ready availability in case of a power outage, and obviously the ability to "carry it with you" as a portable whether traveling, working in the yard, sitting outside on the porch, working on a jobsite, etc.


Just don't carry it by the handle - after 50-something years the plastic of the handle is very brittle. You could end up holding the handle with the waverod and the radio on the ground.

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