[K3CAL] Power Supply Problem

[N3AE]

Karl, 

The Astron is a linear power supply using a series pass transistor as the regulator. The Pyramid is a switching regulator type supply. 

I suspect the RF from your transceiver is getting into the Pyramid and either upsetting the switching regulator feedback loop or triggering a false over-current or over-voltage protection shutdown. Having this happen on just some frequencies doesn't surprise me. It's all a matter of coupling....length of the power cord...length of the DC output wiring to the rig....proximity of the power supply to the rig and antenna... 

I have a small open frame switching power supply that I intended to use to power a 5W HT at home. But any time I transmitted, the RF would shut the switcher off, and that's only a few watts out on 2M. 

Try putting a 0.01 microfarad ceramic capacitor across the power supply's DC output, as close to the terminals as possible. You also might try winding the power supply power cord through a ferrite core if you can find one large enough. Another thing to try is to make sure the power supply case (I'm assuming it's metal) is well bonded to itself. Sometimes paint on the covers prevents good bond to the other parts of the enclosure and RF can get in. 

Shawn 
N3AE 

----- Original Message -----

From: "Karl Long" <karl_g_long at hotmail.com> 
To: k3cal at mailman.qth.net 
Sent: Wednesday, June 10, 2015 8:04:12 PM 
Subject: [K3CAL] Power Supply Problem 

I have two radios, both ICOMs. One is a 706MKIIG, the other is an IC-735. 
I have two power supplies, an Astron 20A (don't know what model). The other is a Pyramid Phase III, model PS-35. Actually, I now have two of them. 

I am using a Gap Titan antenna. 

When I connect either radio to the Astron power supply, they both work fine on all modes, all bands at full power (150 - 200 W). 

With either radio connected to the Pyramid power supply, I can transmit full power, all modes on 10m. But on 20m, I can transmit low poser (10 W) on the 735, but if I go up to about 20 or 30W or more, as soon as I press the PTT on the mike (AM, FM, or key CW) or start to talk on SSB, the power supply trips off line. If I turn the power supply off and then back on, it works again. 

This behavior has been consistent since I setup the antenna. I analyzed the antenna and there is no problem with the antenna on any bands that I used. As far as I can tell, this has happened every time I used the Pyramid power supply. 

My first Pyramid PS-35 finally died. When I turn it on, it immediately blows the fuse. I just borrowed another PS-35 and it behaves the way the first one did, as described above. 

Has anyone heard of a problem like this, or have any suggestions? 

Karl 
KG1L 


______________________________________________________________ 
K3CAL mailing list 
Home: http://mailman.qth.net/mailman/listinfo/k3cal 
Help: http://mailman.qth.net/mmfaq.htm 
Post: mailto:K3CAL at mailman.qth.net 

This list hosted by: http://www.qsl.net 
Please help support this email list: http://www.qsl.net/donate.html 

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mailman.qth.net/pipermail/k3cal/attachments/20150611/9a40a678/attachment-0001.html>