Re: [Repeater-Builder] MASTRII 100 watt PA question
Hello Eric, Thanks for the tip. Last night, the PA failed again. I went to the site and found that the problem is in the 10 watt PA stage, possibly the IC chip or the power control transistor. I brought it home and will look at it in more detail. The strange thing was that it came back to life yesterday, just like a bad connection would cause. 73, Joe, K1ike Eric Lemmon wrote: Joe, Use a magnifying glass to closely check every solder joint for cracks. Some such cracks appear due to temperature cycling over time. I have already had the same problem, where a PA was dead at the site but worked fine on the bench. It was around 40 degrees at the site, but around 70 at the bench. Sure enough, a tiny crack had opened on a PA power lead. Reflowing solder at that connection cured the problem. 73, Eric Lemmon WB6FLY
RE: [Repeater-Builder] MASTRII 100 watt PA question
I had one once that the power control IC seemed to be doing strange things. When we looked at it REAL closely, we noticed that the plastic case around the IC was bulged and split at the top -- best estimate was that it was lightning damage. Very hard to see at the site, easy on the workbench under a 100 watt bulb. :-) Since there's no good source for those IC's, we knew it was gone, but it got thrown in the junk parts box, in-case we ever needed something else off of it, and we swapped out that stage with another one from a different PA that had other problems downstream of that section, and away it went... Nate -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of Joe Sent: Monday, February 23, 2009 5:29 PM To: Repeater-Builder@yahoogroups.com Subject: Re: [Repeater-Builder] MASTRII 100 watt PA question Hello Eric, Thanks for the tip. Last night, the PA failed again. I went to the site and found that the problem is in the 10 watt PA stage, possibly the IC chip or the power control transistor. I brought it home and will look at it in more detail. The strange thing was that it came back to life yesterday, just like a bad connection would cause. 73, Joe, K1ike Eric Lemmon wrote: Joe, Use a magnifying glass to closely check every solder joint for cracks. Some such cracks appear due to temperature cycling over time. I have already had the same problem, where a PA was dead at the site but worked fine on the bench. It was around 40 degrees at the site, but around 70 at the bench. Sure enough, a tiny crack had opened on a PA power lead. Reflowing solder at that connection cured the problem. 73, Eric Lemmon WB6FLY Yahoo! Groups Links
Re: [Repeater-Builder] MASTRII 100 watt PA question
Be suspicious of the power control pot first. Chuck WB2EDV - Original Message - From: Joe k1ike_m...@snet.net To: Repeater-Builder@yahoogroups.com Sent: Monday, February 23, 2009 7:29 PM Subject: Re: [Repeater-Builder] MASTRII 100 watt PA question Hello Eric, Thanks for the tip. Last night, the PA failed again. I went to the site and found that the problem is in the 10 watt PA stage, possibly the IC chip or the power control transistor. I brought it home and will look at it in more detail. The strange thing was that it came back to life yesterday, just like a bad connection would cause. 73, Joe, K1ike Eric Lemmon wrote: Joe, Use a magnifying glass to closely check every solder joint for cracks. Some such cracks appear due to temperature cycling over time. I have already had the same problem, where a PA was dead at the site but worked fine on the bench. It was around 40 degrees at the site, but around 70 at the bench. Sure enough, a tiny crack had opened on a PA power lead. Reflowing solder at that connection cured the problem. 73, Eric Lemmon WB6FLY Yahoo! Groups Links
[Repeater-Builder] MASTRII 100 watt PA question
Hello list dwellers, I went to our repeater site today and found the MASTRII PA dead. I could hear the exciter on my HT and the exciter output checked out OK at 250mw. There was good DC to the PA deck, but no current draw. I checked the usual suspects, the 2 buss wires that carry the DC, the RCA phone jack input, loose connections. etc. Nothing appeared to be bad. I pulled it out and put it on the bench and now it works. The major symptom was no current draw. I can't find a thing wrong at this point. Any ideas? 73, Joe, K1ike Yahoo! Groups Links * To visit your group on the web, go to: http://groups.yahoo.com/group/Repeater-Builder/ * Your email settings: Individual Email | Traditional * To change settings online go to: http://groups.yahoo.com/group/Repeater-Builder/join (Yahoo! ID required) * To change settings via email: mailto:repeater-builder-dig...@yahoogroups.com mailto:repeater-builder-fullfeatu...@yahoogroups.com * To unsubscribe from this group, send an email to: repeater-builder-unsubscr...@yahoogroups.com * Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
RE: [Repeater-Builder] MASTRII 100 watt PA question
Joe, Use a magnifying glass to closely check every solder joint for cracks. Some such cracks appear due to temperature cycling over time. I have already had the same problem, where a PA was dead at the site but worked fine on the bench. It was around 40 degrees at the site, but around 70 at the bench. Sure enough, a tiny crack had opened on a PA power lead. Reflowing solder at that connection cured the problem. 73, Eric Lemmon WB6FLY -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of Joe Sent: Sunday, February 22, 2009 4:56 PM To: Repeater-Builder@yahoogroups.com Subject: [Repeater-Builder] MASTRII 100 watt PA question Hello list dwellers, I went to our repeater site today and found the MASTRII PA dead. I could hear the exciter on my HT and the exciter output checked out OK at 250mw. There was good DC to the PA deck, but no current draw. I checked the usual suspects, the 2 buss wires that carry the DC, the RCA phone jack input, loose connections. etc. Nothing appeared to be bad. I pulled it out and put it on the bench and now it works. The major symptom was no current draw. I can't find a thing wrong at this point. Any ideas? 73, Joe, K1ike Yahoo! Groups Links
