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QMX Q103/Q104 Question :-(

 

I ordered my QMX kit back in March. After a three month wait it arrived. Didn't take long to realize that there was a critical part missing: the binocular core for T-507. I ordered a new one and after another three week wait it arrived. Got it wound and installed (major PITA to do that) this morning. Before doing any power-on I revisited the online assembly manual. Good thing I did, as my original manual said nothing about checking Q103 / Q104. So, I pulled out my VOM and sure enough, this board has a shorted connection.

Well, I sure don't know how you folks are able to move EITHER of those transistors. I gave it a shot with my hot air rework tool for about five seconds and all that managed to do was to partially melt the back of the Mic connector. Placing a 750 watt soldering iron on the back tab of Q103 did nothing as far as being able to move it away from Q104. I saw one post about just clipping out Q103 and replacing it. Is this the easiest method of resolving the problem? And how long does it take to get a new Q103?

Actually, I have another question - what is the status of the newest boards being shipped? Is this Q103-Q104 problem being taken care of before the kits are sent to us builders? If I'm not able to get a replacement Q103 and get it installed properly, or if the QMX blows up when I apply power - what are the chances of buying a new kit and having the same Q103/Q104 issue? THAT would not make me a happy camper....
--
Jim / K7TXA
Eagle, ID

SKCC 10447C
BUG 301
 

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Jim,

Recently ordered kits are checked for the sort before sending them out. Hans says he moves Q103 with a hot air system if the short exists. Maybe he as a smaller nozzle.

I suggest you be sure you get the very latest assembly manual, 1_00i and the transformer document. Hans now recommends a different wind for the T501 transformer

One more thing check that you have the correct values for C525 and C522 as the old assy manual had them swapped.

73,
Cliff, AE5ZA



On Sep 14, 2023, at 13:39, Jim Bennett / K7TXA via <w6jhb@...> wrote:

I ordered my QMX kit back in March. After a three month wait it arrived. Didn't take long to realize that there was a critical part missing: the binocular core for T-507. I ordered a new one and after another three week wait it arrived. Got it wound and installed (major PITA to do that) this morning. Before doing any power-on I revisited the online assembly manual. Good thing I did, as my original manual said nothing about checking Q103 / Q104. So, I pulled out my VOM and sure enough, this board has a shorted connection.

Well, I sure don't know how you folks are able to move EITHER of those transistors. I gave it a shot with my hot air rework tool for about five seconds and all that managed to do was to partially melt the back of the Mic connector. Placing a 750 watt soldering iron on the back tab of Q103 did nothing as far as being able to move it away from Q104. I saw one post about just clipping out Q103 and replacing it. Is this the easiest method of resolving the problem? And how long does it take to get a new Q103?

Actually, I have another question - what is the status of the newest boards being shipped? Is this Q103-Q104 problem being taken care of before the kits are sent to us builders? If I'm not able to get a replacement Q103 and get it installed properly, or if the QMX blows up when I apply power - what are the chances of buying a new kit and having the same Q103/Q104 issue? THAT would not make me a happy camper....
--
Jim / K7TXA
Eagle, ID

SKCC 10447C
BUG 301

 

Jim I ended up desoldering Q103. It was almost ok, except for the source pad which didn't like it. I soldered a wire between the sources of Q103 and Q105, replaced D101 with a THT one (it was toast) and now everything works perfectly.

72/73 de Enzo M0KTZ
 

Well, I obviously re-soldered Q103 in place HI. I realize it was not clear from the previous post...

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