You need to? have a method of proving that the mA setting? (in fact? Gate? bias voltage set ) Potentiometers are in fact? affecting the gates of respective IRF mosfets (by driving up the gate voltage for zero current into the gate )? and preferably eliminate the mosfets ex cct while test is being done ie Gate x 2 are not connected to their pads.? NOw you are at where you are in assly its? going to require you do do some sexy work wiith a solder sucker to get the Gate lines of the IRFs free without? damaging the PCBS.?

Then if you see the? bias V at the free of Mosfet? pad? responding to the respective potentiometer you know that? the bias system is working (you'd expect the bias to be something like 3.8-4.2 V and certainly? movable in this range).? If that's all good you have to suspect the mosfet ccts? ie the Passives that are around the mosfets? (including all your scraping off of? Formvar insulation on magnet wire and soldering that wire? to the pads on the PCBS ,which is often? a show stopper and overlooked , ie both RF? power transformers need close inspection)? and? also the mosfets themselves.? ?If you suspect? the IRFs after all this? then try andfind a? ham with a component tester (microprocessor controlled) or failing that you' will have to build a test bogey? along the lines shown in datasheets to prove each? ?Mosfet is fine under? Dc op condition? and that the transconductance (delta? mA( or amperes)? in? D-G cct versus? delta? V in the gate cct? as a? quotient)? of the IRFs is? within expectations and the two have the same transconductance? (within reason, Hans does not offer them as a formal matched pair).?

The fact that the unit is pulling 140mA base current does not mean that the driver? CCT of BS 170s is all good.... but that numbers sounds about right for linear operation of? BS 170s with a 12 V Vcc,? ie 70mA per BS 170 Drain - Source? circuit.?

?

TEF

But again why would you like to listen to the jam of the Digi modes signals?

Hello everyone

I ordered and assembled this PA. I followed every step as carefully as I can while assembling.

When the pots closed fully (to counter-clockwise) current consumption is 140mA stable (TX is grounded, no RF) when I apply 12 volts. When I start to turn one of the pots, it is still 140mA stable. Same with the other pot. Nothing is changing. So I cannot adjust them to 125mA (total of 250mA).

I checked transistors (IRF510) and their reading is fine. I cut the power and I touched them first (against static) and checked thier resistance measurement from their legs and their readings are same. They seem OK.

I think I am missing a point. I am newbie about PAs. I send some detailed pictures. Any help would be appreciated.

?

73 TA2CCN

Hello, I would advise you to visit local grocery story into food storage section to look for food containers. They are waterproof, good and solid plastic and the most important - you could get an idea and affordable experience on how big you actually need. I store a lot of "not only electronics" in them, as they being 'retired' from kitchen. Any brand is good, as far case has glued silicon strip in a cover and all-perimeter locks. 73 de OH2DZ

Just a quick update regarding my issue with the LCD:

I ended up sending the rig to Jeff Moore, W1NC, for further inspection. He did an AMAZING job of troubleshooting and fixing the LCD data connection. There was a broken PCB trace which he substituted with a jumper wire. Not only did he resolve the LCD issue, but he also spotted and fixed a couple of other issues with the TX and SWR meter capabilities of the rig.

I have made several QSOs with the QMX and I cannot emphasize enough what a great piece of kit it is.

I would like to note that Jeff Moore provides this service at no cost, only charging for shipping and parts. Out of kindness and emphasizing the notion of "Hams helping Hams," he does not demand any money for the valuable time he puts in. Please, if you end up sending him a rig, consider donating, as he dedicates all donations to maintaining a reliable inventory of parts to continue this great service for the ham radio community.

开云体育

"why one would need to have audio on in Digi modes?"

I disagree, though I agree that some would not!

My ear can't decode the signals, but I can hear how everything is going. Agree, that it's elsewhere in the displays. But if I'm listening, I don't have to search it out.

Just sayin'. OK that YMMV!

73, Paul -- AI7JR

-- 
Paul -- AI7JR

A thought: I wonder why one would need to have audio on in Digi modes? Just mute it.