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Author Topic: RFI In my Samlex SEC 1223  (Read 21293 times)
K9BHP
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« on: September 25, 2014, 03:24:36 PM »

Hi 'y'all  Smiley
I am not sure if this question has been asked before, but I have RFI problems with one of my SAMLEX SEC 1223.
I am using two and one produces chirping sounds and swings in accordance with my modulation when I transmit. It sounds as if it is trying to act like a miniature loudspeaker.
I have opened it and looked around but cannot see anything that might be loose.
My rig is a TS-480 HX and is is properly grounded. It requires 2 power supply's to get enough AMP.
The other SEC 1223 does not have that problem.
Thank you for your help.
73
Ben, K9BHP

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KH6AQ
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« Reply #1 on: September 25, 2014, 04:34:18 PM »

Is it RFI or is it not able to handle the current draw? If you have a dummy load that will narrow it down to one or the other.
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K9BHP
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« Reply #2 on: September 25, 2014, 04:41:39 PM »

Sorry, no dummy load.
Thank you for your feedback.
73
Ben
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KD0REQ
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« Reply #3 on: September 25, 2014, 07:50:02 PM »

out of the box, those supplies are not designed for parallel operation for higher current.  whichever one has higher voltage is going to supply the power, and it may backfeed the other one.

the real fix is to get a bigger power supply.

you might be able to play "phone company" and make that work if you scare up some 30 to 50 amp stud mount rectifiers (or an output diode trio for an alternator) and a moosey heat sink.  central offices use thousands of amps of 48 volts DC for "battery."  there are big banks of batteries... used to be 2 volt wet cells, starting to go to lithium batteries... and a bunch of big "rectifiers," common-control AC to DC regulated power supplies for charging and primary service somewhere in the 52.5 volt range.  if AC power goes out, the "rectifiers" are typically run from diesel generators.  our office has three 2.3 megawatt nameplate generators.

all sources feed the power busses through big-ass silicon rectifiers.  everything is fused everywhere.  you would need to as well.

while your general duty power supply doesn't have common voltage control, you CAN bank multiples through big-ass rectifiers so any source never sees any other source, just the load.  then you will have to adjust the voltage regulator in all the supplies to the same voltage under load.

still easier and cheaper to get the right supply.  any hamfests near you soon?
« Last Edit: September 25, 2014, 07:53:34 PM by KD0REQ » Logged
K9BHP
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« Reply #4 on: September 25, 2014, 09:11:01 PM »

Thank's for your response.

Quote
the real fix is to get a bigger power supply.

I guess that's it.

For the rest of your response, I'm going to have to read that a couple of times to only begin to understand.
Thank you for your help.
I think that's what I am going to do.

73
Ben
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ND6P
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« Reply #5 on: September 26, 2014, 05:29:09 AM »

On the 1223 that is acting up, I would check/replace the large electrolytic caps.  I've seen them go bad before.

Jim/ND6P
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KH6AQ
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« Reply #6 on: September 26, 2014, 06:18:52 AM »

The TS-480HX does not parallel the power supplies, it has two separate PA stages. The SAMLEX power supplies have enough current capability to run this radio at full power.

One test is to swap the location of the power supplies. If the problem follows the power supply it has a problem. If the problem follows the PA it is the problem.

As mentioned, another test is a dummy load. A 250 watt, 120 VAC incandescent lamp can be used. At 200 watts it presents a resistance of 60 ohms. Cold it's around 10 ohms and I don't know whether the TS-480HX will deliver enough power (it will cut back initially) to bring the lamp up. A cheap desk lamp can be used with a PL-259 on the end of the cord. If you don't have a PL-259 one wire can be pushed into the TS-480HX coax connector and the other wire wrapped around the connector shell. Crude but effective. If you don't have a desk lamp the wires can be connected directly to the lamp base. The one is soldered to the center and the other is wrapped around the threads.
« Last Edit: September 26, 2014, 06:24:38 AM by WX7G » Logged
K9BHP
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« Reply #7 on: September 26, 2014, 07:38:04 PM »

Quote
On the 1223 that is acting up, I would check/replace the large electrolytic caps.  I've seen them go bad before.

Thanks for your reply. I wonder where to find those electrolytic caps inside? Do you happen to have a picture? And also, where do I buy a replacement.
Your help is appreciated.
Thank you.
73
Ben, K9BHP
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K9BHP
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« Reply #8 on: September 26, 2014, 07:54:42 PM »

Quote
The TS-480HX does not parallel the power supplies, it has two separate PA stages. The SAMLEX power supplies have enough current capability to run this radio at full power.

One test is to swap the location of the power supplies. If the problem follows the power supply it has a problem. If the problem follows the PA it is the problem.

As mentioned, another test is a dummy load. A 250 watt, 120 VAC incandescent lamp can be used. At 200 watts it presents a resistance of 60 ohms. Cold it's around 10 ohms and I don't know whether the TS-480HX will deliver enough power (it will cut back initially) to bring the lamp up. A cheap desk lamp can be used with a PL-259 on the end of the cord. If you don't have a PL-259 one wire can be pushed into the TS-480HX coax connector and the other wire wrapped around the connector shell. Crude but effective. If you don't have a desk lamp the wires can be connected directly to the lamp base. The one is soldered to the center and the other is wrapped around the threads.

I am a little hesitant to try that.
I wished you were my neighbor...
73
Ben
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KD8IIC
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« Reply #9 on: September 27, 2014, 02:49:12 AM »

  Does not seem that anyone has considered that you well may have your Mic Gain and or processing turned up too high. That was exactly my trouble here. I had your symptoms. I have three of these and they are fine supplies...
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K1DA
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« Reply #10 on: September 27, 2014, 11:27:45 AM »

Would not a .1 ohm equalizing resistor  in each plus lead work for parallel power supplies.  Power supplies using multi transistor output stager are  often equalized in that way.
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K9BHP
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« Reply #11 on: September 28, 2014, 04:17:21 PM »



Here is a picture of the three large electrolytic caps near the DC terminals.
Like Jim ND6P said, they seem to be bulging and leaking.
Unfortunately I have two left hands and have never soldered anything like that.
Does anyone know if there is a place that repairs power supply's and is not too expensive?
73
Ben
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K9BHP
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« Reply #12 on: September 28, 2014, 04:50:08 PM »

Quote
Does not seem that anyone has considered that you well may have your Mic Gain and or processing turned up too high. That was exactly my trouble here. I had your symptoms. I have three of these and they are fine supplies...

Thanks for your input. Tried that and no change. I now believe the electrolytic thingies are causing the problem.
See picture above.
73
Ben
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KH6AQ
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« Reply #13 on: September 28, 2014, 05:48:31 PM »

The Samlex is only $115 and isn't worth fooling with.
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K9BHP
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« Reply #14 on: September 28, 2014, 06:34:13 PM »

Quote
The Samlex is only $115 and isn't worth fooling with.

Thank you for your words of advice David.
Lucky me, Jim, ND6P offered to repair it.
Being a fairly new ham I of course appreciate the offer.
My soldering skills are definitely limited.
Jim is a seasoned ham and I am sure he knows what he is doing, quite unlike me   Embarrassed
73
Ben
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