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Author Topic: New Kenwood TS-520S in the box!?  (Read 853 times)
K3OD
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« on: May 09, 2004, 10:11:17 PM »

Hello All,

Recently, I found and (re)purchased my first ham rig...Kenwood TS-520S unused and still in the box! As I await it's arrival, should I be concerned because it has been sitting for 25 years somewhere? Should it fire up like new? Is there anything I should be aware of...or precautions before transmitting? Thanks in advance!

John, K3OD
 
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WB2WIK
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« Reply #1 on: May 10, 2004, 12:05:18 PM »

I'd be quite concerned.  Unless it's been stored in a cool and very dry environment, there's a pretty good chance the high voltage power supply will have problems (electrolytic capacitors), and relay and switch contacts will probably all be oxidized and require cleaning.  The low voltage circuits which work the receiver and low-level TX stages are probably okay.

I'd probably bring it up slowly using a variac on the AC primary, to see if I get any sparks or failures as the HV capacitors are forming with their first charge in a quarter century...

WB2WIK/6
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W7DJM
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« Reply #2 on: May 10, 2004, 01:28:08 PM »

Since you said this was your first rig, I would doubt that you have a "variac"

Another way to do this, IF you are comfortable with working with "juice,"  is to wire a lamp socket in series with an outlet--simply done with a cheap extension cord and a cheap replacement lamp socket.

Then, start out with about the smallest bulb you can find, say 15 watts, then go around and pile up as many bulbs around the house as you can find, go up to 25, 40, 60, 100, etc, and probably you'll have to maybe buy a "big" bulb, say 200 or 300.

I don't remember if this rig has a filament switch to allow for low drain operation during receive only.

If so, make sure the switch is ON before you do this.
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K3OD
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« Reply #3 on: May 10, 2004, 01:32:02 PM »

Hello again,

Wondering "how slow" you think I should increase the voltage? Thanks again...

John, K3OD
 
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WB2WIK
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« Reply #4 on: May 10, 2004, 02:30:04 PM »

The TS-520S does have a HEATER switch, but as soon as you apply AC power, regardless of that switch's setting, everything powers up at once (except possibly the three tube heaters).  The HEATER switch is mostly there to save battery power for mobile/portable operations when the rig might be used only for receiving.

As for "how much, how fast?," if you do have a variac or access to one, I'd crank it from "zero" slowly upwards, watching the HV meter scale on the TS-520S front panel.  As you know, if the rig's HV supply really works, it produces about 800-900V no-load, or about 700V "key-down" when transmitting.  I think that's the first part of the rig likely to fail from long non-use.  As you crank up the mains voltage, the HV should rise proportionately.  If you apply 13Vac, you should achieve 80-90Vdc on the HV scale.  At 26Vac, it should double to 160-180V, and so forth, until you reach full line voltage and 800-900Vdc indicated.  I'd turn it up very slowly over the course of maybe an hour or so.

Again, if the HV power supply (caps) hold up, there's likely to be some other minor problems such as switch and relay contact oxidation, but you can probably fix those at little or no cost, just a bit of work.  If the rig's been stored in an uncontrolled and humid environment, I think you're likely to have more problems than if it had been stored in cool and dry environment.

WB2WIK/6
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K3OD
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« Reply #5 on: May 10, 2004, 09:31:54 PM »

Hello again,

I'm having a hard time locating a variac...and the series wired bulbs maked me a little nervous ;-) I also learned that perhaps "pulsing" the power off and on in increasing time factors over a period of approx 10 minutes can also be a safeguard. Any thoughts on this method? Thanks again!

John, K3OD
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WB2WIK
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« Reply #6 on: May 11, 2004, 11:46:29 AM »

If you want to *buy* a variac, they're available 24/7 for overnight shipment from http://www.variac.com website.  Unfortunately, they're not cheap!

The ones I have I purchased mostly from Fair Radio Sales (surplus) http://www.fairradio.com/   Sometimes they have some, sometimes they don't.

I've never heard about the method you described but it doesn't sound very logical.  The idea of using a variac to bring the voltage up slowly is to allow the electrolytic capacitors to form without slamming them all at once with multiple Joules of energy from the transformer.  Simply switching the rig on and then back off doesn't accomplish this, at all.

Wiring resistance in series with the AC line, however, does accomplish this, and that's what the other recommendation about wiring light bulbs in series with the rig was about.  It's a little bit hazardous if you're not very careful, but the "light bulb" method does work.

WB2WIK/6
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K3OD
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« Reply #7 on: May 11, 2004, 10:18:59 PM »

W7DJM & WB2WIK,

Thanks again for the great info and your time. Perhaps I will try the lightbulb method. I'm a little confused though...would I first start with the highest wattage bulb then work down? Wouldn't this allow more and more current to the rig as I go to the "smaller" bulbs? Also, would the wiring be such that BOTH AC wires are attached to the bulb socket and then continue on to the rig? Wouldn't this be a circuit in parallel? I'm a little rusty with my electrical circuits, HI HI.

John, K3OD
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KE4DRN
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« Reply #8 on: May 12, 2004, 12:16:02 AM »

hi john,

Here is a link for you

http://antiqueradio.org/dimbulb.htm

73 james
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K3OD
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« Reply #9 on: May 12, 2004, 12:40:40 AM »

James,
Thanks for the great link...perfect!
John, K3OD
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K3OD
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« Reply #10 on: May 12, 2004, 03:24:21 PM »

Finally found a variac to use! Last question I have is if it is needed to be used in any way while transmitting?...because of course the current draw is triple while transmitting. I have access to an 8A model which will be adequate to power up the rig even with the heaters on while receiving. Thanks to everyone for the great advice! 73.

John, K3OD
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WB2WIK
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« Reply #11 on: May 13, 2004, 02:14:51 PM »

The 8A variac will work just fine, even if you want to transmit.

The TS520S cannot possibly draw more than 8A when transmitting -- impossible.  It should draw about 3A key-down on transmit, and less than 1A in receive, when powered by a 120Vac line.

WB2WIK/6

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K3OD
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« Reply #12 on: May 14, 2004, 06:45:30 AM »

Thanks WB2WIK for all the great info...will let everyone know how it works out.

John, K3OD
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