QIX Power Supply

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QIX Power Supply

Postby K9ACT » Tue Nov 09, 2010 7:40 pm

I am posting this for a friend who is tired of waiting to be approved to post.
.................

What is the purpose of R2 (6.8K) in the dc output of the QIX PWM Power Supply? In the RX position it is in series with the power supply DC output. In the TX position the resistor is bypassed. Is the resistor serving as a pre-charge for the filter capacitors on the PWM output board? Also, should the power supply have a bleeder resistor?

George

....................

js
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Re: QIX Power Supply

Postby kf1z » Tue Nov 09, 2010 11:27 pm

First question...
Sure, I suppose..

I think the reason the resistor that is in parallel with the relay contacts is there is to keep arcing to a minimum should the relay be dropped out under load..
And, when the relay is switched off, there is a few milliseconds that current is still being drawn by the modulator, and this helps bleed the filter caps down very quickly...

something along those lines..

I'm not an engineer, so I just put them in, because they are in the schematic. :D



To the second question


Since you mention 6.8k for the other resistor, it is clear you have schematics that were done sometime in the last year or a little more, when the bleeder resistor was omited by mistake.....

As I told Jack earlier this summer, there "always" WAS a bleeder there, and should be.......

Go look at the schematics again , they were changed 2 or 3 months ago..
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Re: QIX Power Supply

Postby steve_qix » Wed Nov 24, 2010 8:15 pm

K9ACT wrote:I am posting this for a friend who is tired of waiting to be approved to post.
.................

What is the purpose of R2 (6.8K) in the dc output of the QIX PWM Power Supply? In the RX position it is in series with the power supply DC output. In the TX position the resistor is bypassed. Is the resistor serving as a pre-charge for the filter capacitors on the PWM output board? Also, should the power supply have a bleeder resistor?

George

....................

js


Hmmmmmmmmmmm I don't have any outstanding requests from anyone to join the forum. Who is it? Did whomever it is fill out the "request form" to post - which is emailed directly to me? We get HUNDREDS of spammers trying to register here, so I went to the form. I verify the info, and the person is approved. See the forum list for the "how to register" forum. I know I've been working more than 80 hours per week on a big software development project, but I don't think I missed any emails!
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Re: QIX Power Supply

Postby steve_qix » Wed Nov 24, 2010 8:18 pm

K9ACT wrote:I am posting this for a friend who is tired of waiting to be approved to post.
.................

What is the purpose of R2 (6.8K) in the dc output of the QIX PWM Power Supply? In the RX position it is in series with the power supply DC output. In the TX position the resistor is bypassed. Is the resistor serving as a pre-charge for the filter capacitors on the PWM output board? Also, should the power supply have a bleeder resistor?

George

....................

js


Oh, to answer the question :D The resistor across the relay is indeed there to keep the caps in the modulator charged up between transmissions. Also, to bleed off those same capacitors when the rig is turned off or in receive for a long time, and the main power supply capacitors slowly discharge through the [small current] bleeder.

The bleeder should be there, across the main filter caps, and chosen so that it will mostly discharged the caps over about a 10 minute period of time.
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