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 Post subject: Zenith Royal 3000-1
PostPosted: Feb Sun 05, 2012 11:17 pm 
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I have a Zenith Royal 3000-1 which I purchased direct from Zenith in 1967 while teaching in the West Indies. The radio is in good working order and I currently power it in my workshop with Zenith Transistor radio AC converter S-65074. I would like to power the radio directly off a 12 volt car battery when I am at my hunting cabin. How would I accomplish this?


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 Post subject: Re: Zenith Royal 3000-1
PostPosted: Feb Sun 05, 2012 11:54 pm 
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Location: Sunnyvale CA
Skrippa wrote:
I have a Zenith Royal 3000-1 which I purchased direct from Zenith in 1967 while teaching in the West Indies. The radio is in good working order and I currently power it in my workshop with Zenith Transistor radio AC converter S-65074. I would like to power the radio directly off a 12 volt car battery when I am at my hunting cabin. How would I accomplish this?


I can figure out the pin assignments on the battery plug, but good old Alkaline D cells will run it longer than any reasonable requirement - I would guess around 750 hours, which is a heck of a lot of radio listening. That's certainly what I would do. If you don't have a battery box you can make one up pretty easily for a few dollars.

If you want to hook it into the 12V input on the side, it's a 2.5 MM Mono mini-plug and the tip is *negative*. If you get it the wrong polarity there's a good chance you will damage the radio.

BTW, by all means keep using it, but the original Zenith converter/wall-wart is likely to be getting a bit tired at this point. If you start getting any sort of a hum on the radio , you might need to rework the converter.

Brett


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 Post subject: Re: Zenith Royal 3000-1
PostPosted: Feb Mon 06, 2012 4:26 am 
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Location: Utica, NY 13502 (USA)
If you do use a car battery feeding a plug for the 12 volt external power connection, be sure the plug is in the jack before connecting the other end of the wire to the battery. A brief short can occur when inserting the plug into the jack because of the type of plug and jack Zenith used. Usually, the AC power supply can withstand this but the high current available from a car battery could cause problems with the jack, the plug or the wire. Like Brett said, I think you'd be better off just using Alkaline D cells.

Dave


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 Post subject: Re: Zenith Royal 3000-1
PostPosted: Feb Mon 06, 2012 4:45 am 
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Dave Doughty wrote:
If you do use a car battery feeding a plug for the 12 volt external power connection, be sure the plug is in the jack before connecting the other end of the wire to the battery. A brief short can occur when inserting the plug into the jack because of the type of plug and jack Zenith used. Usually, the AC power supply can withstand this but the high current available from a car battery could cause problems with the jack, the plug or the wire.
Dave


I doubt the wire would be affected, but the power jack in the radio is BY FAR the least reliable thing in the system, and anything you can do to help it would be good. Although I would guess that the difference in the arc when it makes or breaks is pretty small. It's 13.5 volts or so and the power supply has a pretty good-sized cap in it to give you enough current capability to pop it pretty well, I would think. I hadn't thought about that before but if that is the issue slapping a .05 MFD across the points, er, contacts, would reduce it.

Those jacks are very nasty little bits, and once they get to the point of making poor contact, no amount of fiddling will get them right again. Brass doesn't make for a very good spring! I have had problems with them in a Royal 3000-1, a 2000-1 and *two different* Royal 810s. I ended up defeating them with jumpers on the 2000 and 3000. I can't use the power supply any more but they run so long on modern cells that you don't need it.


On the 810s, it manifested itself as poor FM performance while AM was OK! And I wasn't using an external power supply, just batteries. Let's just say the power jack was the last place I looked for that particular problem. Somehow around hour 12 of troubleshooting, I accidentally pushed on the jack while I was trying to get FM to work, and magically, it started working perfectly. The contact that opens when you put in the power plug was making poor contact, and it must have been just poor enough that the difference in power draw between FM and AM made FM not work properly. It would play but with a lot of distortion. All the voltages I measured were at least close to the spec values. I was so irritated that I just soldered the contacts together. I haven't found a modern switching jack that will fit exactly yet, but I will sure replace them all when I have a chance.

Brett


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 Post subject: Re: Zenith Royal 3000-1
PostPosted: Feb Mon 06, 2012 5:31 am 
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Location: Dallas, TX - in the city but with bobcats and coyotes
If I remember correctly, the caps are rated at 12V. A car battery can run to 13.65 or even more. Hmmm - not for my radio I wouldn't. I'd build a current-limited 9 or 10 volt regulator to protect the radio. I presently run one at 9 volts. It doesn't play as well at high volume but, other than that, it works fine last a long time.
I strongly agree, a car battery could possibly arc-weld the jack if the car fuse didn't blow.

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 Post subject: Re: Zenith Royal 3000-1
PostPosted: Feb Mon 06, 2012 5:50 am 
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Location: Palmerston North, New Zealand
...buy why bother. A set of "D" cells will last ages - the current draw is notably low.

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 Post subject: Re: Zenith Royal 3000-1
PostPosted: Feb Mon 06, 2012 6:05 am 
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Location: Sunnyvale CA
mescalero wrote:
If I remember correctly, the caps are rated at 12V. A car battery can run to 13.65 or even more. Hmmm - not for my radio I wouldn't. I'd build a current-limited 9 or 10 volt regulator to protect the radio. I presently run one at 9 volts.


The caps that are right across the power supply are 25V, so I think that's OK. The wall wart is about 12.5. An absolutely brand-new set of alkaline Ds are 13.68, tested it just yesterday (for unrelated reasons). It will run on 9 volts but mine lost some performance below about 10V.

I don't see any problem running off of "12v" car supplies, just don't see much reason to do it when internal batteries last so long.

Brett


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 Post subject: Re: Zenith Royal 3000-1
PostPosted: Feb Mon 06, 2012 6:18 am 
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Yep... just buy a set of new alkaline batteries, (or rechargeables).
You'll get several hundred hours of carefree reception.

~ Mitch ~


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 Post subject: Re: Zenith Royal 3000-1
PostPosted: Feb Mon 06, 2012 1:53 pm 
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Brett_Buck wrote:
Dave Doughty wrote:
A brief short can occur when inserting the plug into the jack because of the type of plug and jack Zenith used.......the high current available from a car battery could cause problems with the jack, the plug or the wire.

I doubt the wire would be affected

I think that sending several hundred amps through the small-guage wire usually used in this application if even for an instant could easily damage the wire if the circuit isn't protected by a fuse.

Dave


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 Post subject: Re: Zenith Royal 3000-1
PostPosted: Feb Mon 06, 2012 7:53 pm 
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Dave Doughty wrote:
Brett_Buck wrote:
Dave Doughty wrote:
A brief short can occur when inserting the plug into the jack because of the type of plug and jack Zenith used.......the high current available from a car battery could cause problems with the jack, the plug or the wire.

I doubt the wire would be affected

I think that sending several hundred amps through the small-guage wire usually used in this application if even for an instant could easily damage the wire if the circuit isn't protected by a fuse.


Not to be argumentative, but, several hundred amps? How long does it take to charge up a 500 mfd cap to 13V at 200 amps? How much energy is that, total, and how hot would the wire get?

The thinner the wire the lower the current. It's still only 13V. Figure the wire at 1/4 ohm and the battery at essentially 0 ohms for conservatism, the peak current is only 32 amps, which will burn it up pretty quick, but not in the few microseconds it takes to charge the cap. The total energy is only 84 mjoules, even assuming it all got dumped as heat into the wire, you would never tell the difference, no matter what the current might be. The time constant is .0005*r, sounds pretty quick to me.

There would be a somewhat higher current spike with the car battery than a D cell, but that would only be a problem with the jack arcing, not with damaging the wire - it's the same energy.

Brett


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 Post subject: Re: Zenith Royal 3000-1
PostPosted: Feb Mon 06, 2012 10:52 pm 
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No argument but I was thinking about the plug shorting across the tip and ring and possibly welding itself in place as it is inserted into the jack. (This can happen because of the type of mini-plug Zenith uses on the 3000-1) I was thinking that the exceedingly high current available from a car battery might easily melt the wire. Your analysis of charging a 500 uf cap is, of course, correct but that's not what I was talking about.

I had a similar experience when I clipped a small air compressor to a car battery and didn't realize the wire was shorted together at the compressor. The 18 ga wire melted in less than 2 seconds.

Dave


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 Post subject: Re: Zenith Royal 3000-1
PostPosted: Feb Tue 07, 2012 12:01 am 
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Dave Doughty wrote:
No argument but I was thinking about the plug shorting across the tip and ring and possibly welding itself in place as it is inserted into the jack. (This can happen because of the type of mini-plug Zenith uses on the 3000-1)


Oh, that'se a good point, I misunderstood. The original Zenith plug had a wide gap between the pin and the shield to avoid that but a current mono-mini-plug wouldn't. I guess we should be using a stereo mini-plug and just ignore the middle ring.

Brett


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 Post subject: Re: Zenith Royal 3000-1
PostPosted: Feb Tue 07, 2012 12:49 am 
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Brett_Buck wrote:
I guess we should be using a stereo mini-plug and just ignore the middle ring.

Excellent idea!

Dave


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 Post subject: Re: Zenith Royal 3000-1
PostPosted: Feb Tue 07, 2012 6:35 am 
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Location: 253 Blanche St. Plymouth, MI USA
Better idea is to install some good quality alligator clips onto a durable coiled cord type cigarette plug and clip them onto the battery terminals inside. Shut the door and plug it in.

I have done this for several customers who have the version of the 1000 or 3000 that do not have the power plug.

Mark Oppat
www.oldradioparts.net


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 Post subject: Re: Zenith Royal 3000-1
PostPosted: Feb Tue 07, 2012 7:39 pm 
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I thank all of you who replied to my post regarding the Zenith Royal 3000-1 hook up to a car battery. I will be taking the advice that many of you offered and using the 8 alkaline D cells. The pack for the cells is in the back of the radio but I have never had to use it. I notice that a sticker on the pack states to use standard Carbon-Zinc type D cells. Am I correct in assuming that alkaline D cells will work just as well ?
Again thank you all for your input and advice. Very much appreciated.

Skrippa


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 Post subject: Re: Zenith Royal 3000-1
PostPosted: Feb Tue 07, 2012 8:21 pm 
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Skrippa wrote:
I thank all of you who replied to my post regarding the Zenith Royal 3000-1 hook up to a car battery. I will be taking the advice that many of you offered and using the 8 alkaline D cells. The pack for the cells is in the back of the radio but I have never had to use it. I notice that a sticker on the pack states to use standard Carbon-Zinc type D cells. Am I correct in assuming that alkaline D cells will work just as well ?
Again thank you all for your input and advice. Very much appreciated.

Skrippa


Alkaline D's will work dandy and give you something over 500 hours of playing time. You need a 9th one to get the dial light to work.

Brett


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 Post subject: Re: Zenith Royal 3000-1
PostPosted: Feb Tue 07, 2012 8:32 pm 
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The battery pack does, indeed hold 9 D-cells. But a word of caution (as if there haven't been enough words of caution already)...when Alkaline cells are installed, the weight of the radio increases significantly. It's best not to carry the radio by the antenna/handle when alkaline batteries are in it. Probably shouldn't carry it by the handle even without batteries since the handle is a known weak point on this model as well as on the Royal 1000 series.

Dave


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 Post subject: Re: Zenith Royal 3000-1
PostPosted: Feb Tue 07, 2012 8:52 pm 
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Dave, havent seen much trouble with the handle/ antennas on the 1000 and 3000 TO's. They lock in pretty well it seems. More often trouble on the tube type TO's. Main failure on the 1000 and 3000 series is the upper door hinge breaking and the upper door being lost.

Mark Oppat
www.oldradioparts.net


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 Post subject: Re: Zenith Royal 3000-1
PostPosted: Feb Tue 07, 2012 10:17 pm 
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oldradioparts wrote:
Dave, havent seen much trouble with the handle/ antennas on the 1000 and 3000 TO's. They lock in pretty well it seems. More often trouble on the tube type TO's. Main failure on the 1000 and 3000 series is the upper door hinge breaking and the upper door being lost.

Mark Oppat
http://www.oldradioparts.net


I think it's tough enough if you just carry it around normally. There's a lot of broken handles but most of them seem to be from people pressing down on them, not pulling up. That causes the bottom half of the handle to break and slide WRT the top part, which makes it weaker and it breaks, too. I carry mine by the hinge end of the handle, not in the middle or the latch end.

There is supposed to be a pin in the latch end of the handle, 1/16" diameter. It goes into a hole on the top of the latch to keep the latch from opening when you are carrying it. If that is missing, it's pretty easy to release the latch accidentally, or to have the metal handle supports spread apart and release the handle. The cast metal endplates are not very tough at all, just cast zinc, and bend very easily. You will see them on eBay with them both bent one way or the other from being dropped. They are easy to bend back, at least, as long as you are careful. I had one that looked like it had been run over with a tank, with a 1/2" deep bend over the distance of about an inch. A urethane hammer and a positive mental outlook, and it went right back to normal in about 5 well-placed whacks.

For as heavy as it is and as much metal as there is in it, it's a lot more fragile than you would expect. I have one where the door hinges broke, and all of the 1000/3000 series I have worked on had the dial glass either loose or down to one or two pins holding it. To me that's the biggest problem with durability, and it's a Royal pain (heh-heh) to fix since the whole thing is held together with spring clips. I just glue them in with epoxy putty, it's not like I am going to be violating the warranty.

Brett


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 Post subject: Re: Zenith Royal 3000-1
PostPosted: Feb Wed 08, 2012 2:21 am 
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The handles on the 1000 and 3000 solid state TO's are very weak as they are hollow to house the waverod antenna. It's rare to find one that doesn't have a crack or two in the handle.

Bryant and Cones recommend packing the handle with epoxy putty, which I do on all of mine. Even then, when carrying either of those radios, always keep one hand under the radio to support it.

Although the tube TO handles are more robust, keeping one hand under the radio is not a bad idea.

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