[hpsdr] Munin

[Ken Shutt]

Hi Tom & Tony,

My Munin is mounted in the Pandora enclosure so I can’t get a photo without disassembling everything.  My Penelope exciter could only drive Munin to 50 watts on 6 m.  The caps failed while testing on 6 m.  I replaced all 4 with new 220 pf units.  I don’t plan to use on 6 m so I did not troubleshoot further.  The rf current through each of the 220 pf caps at 50 mhz and 100 watts output will be about 5 amp (if my calc is correct).  That is a lot of current and it could account for the heating.

73 de Ken W5KQ


From: Tom McDermott 
Sent: Saturday, January 18, 2014 11:33 AM
To: Tony Hagen ; kgshutt at cox.net 
Cc: hpsdr at lists.openhpsdr.org 
Subject: Re: Munin

Hi Tony.

Here's a couple photos of the suspect area.
000 is a picture of the crater in C27, the second is after replacing C25/C26/C27.
Have not checked for heating in the 4 new capacitors. Would need to setup a fan for the heatsink before starting longer term soak test.

https://www.dropbox.com/sh/9tsredh4l7dduv6/gdVyIqC2sl


-- Tom, N5EG

 
From: Tony Hagen <prosdr at gmail.com>
To: kgshutt at cox.net; tom.mcdermott4 at yahoo.com 
Sent: Friday, January 17, 2014 8:49 PM
Subject: Re: Munin


Hi,

Please do send me a photo of your assembled Board. OH BTW I have not installed T5 and all which is marked DNI

73s
Tony

From: Tony Hagen 
Sent: Saturday, January 18, 2014 10:01 AM
To: kgshutt at cox.net ; tom.mcdermott4 at yahoo.com 
Subject: Munin

Hi Ken and Tom

I am also getting identical results with a difference. At 6 metre the capacitors are heating.

I am testing in standalone mode with PTT and jumper shorted. I am using a signal generator as input to excite.

Is is possible to replicate my test setting at your end at 6 metre continuously with at least 10 minutes in PTT mode – keep checking the temperature of 220pf/500v capacitor.

This is my 2nd munin which I am testing – its not mounted in any enclosure yet so no fan yet but I am using two identical heatsink during my test

73s
Tony


-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.openhpsdr.org/pipermail/hpsdr-openhpsdr.org/attachments/20140119/1acb21af/attachment-0004.htm>