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Re: TRX1 PA Board

Matti I did as you suggested but nothing changed. I turned each trimmer many times and the ohm meter went up and down but never down enough. The highest values were about 2.5K. Please note that the trimmers I got were different from the ones pictured. Those pictured were large, white ones while the ...
by WB2MSC
23 Nov 2012 01:04
 
Forum: Juma Discussion
Topic: TRX1 PA Board
Replies: 10
Views: 8309

Re: TRX1 PA Board

Matti

I just remembered that the pots looked a bit old and the contacts weren't shiny. I put some liquid flux on the contacts before soldering. The joints seem ok as the pots didn't fall off but maybe there is still some oxidation which could make the resistance higher.

Marc
by WB2MSC
22 Nov 2012 18:31
 
Forum: Juma Discussion
Topic: TRX1 PA Board
Replies: 10
Views: 8309

Re: TRX1 PA Board

Hey Matti I assume that the center leg of the pot is the leg that is on its own side. If that is true, I'm getting the same range of readings. The resistance does change when I rotate the screws on the pots. I even tried a different multimeter. Just to be certain, I am using the mounting screw holes...
by WB2MSC
22 Nov 2012 18:15
 
Forum: Juma Discussion
Topic: TRX1 PA Board
Replies: 10
Views: 8309

Re: TRX1 PA Board

Matti,

I took the readings from the GATE-TO-Grnd of the 3 MOSFETS and come up with 700 - 800 ohms each. That seems to be the best I can do. Is that reasonable for the biases to start with?

Marc WB2MSC
by WB2MSC
22 Nov 2012 15:46
 
Forum: Juma Discussion
Topic: TRX1 PA Board
Replies: 10
Views: 8309

Re: TRX1 PA Board

Thanks, Matti

See, I did learn something today.

Kiitos. Ystävällisin terveisin, Marc
by WB2MSC
21 Nov 2012 19:18
 
Forum: Juma Discussion
Topic: TRX1 PA Board
Replies: 10
Views: 8309

TRX1 PA Board

Greetings from New Jersey after the storm The instructions for the PA board (TRX1) say to ensure the lowest resistance for the MOSFETS biases gate to ground. Taking TR1 as an example, do I use an ohmeter at the gate of TR1 and the ground of R2? Or just from the gate to ground? What is the best way t...
by WB2MSC
21 Nov 2012 16:17
 
Forum: Juma Discussion
Topic: TRX1 PA Board
Replies: 10
Views: 8309

TRX1 Tune-Up

Hello again, I am progressing nicely with the TRX1 build. Just thinking down the road to the tune-up phase, which board should be tuned first and second? Are the tune-up guides on the website still accurate or has someone come up with a different, unified procedure accross the three boards? Thanks o...
by WB2MSC
20 Nov 2012 16:40
 
Forum: Juma Discussion
Topic: TRX1 Tune-Up
Replies: 1
Views: 2166

TRX1 74HC4052

Hey guys, I completed the main board on the TRX1 and have one part left over. I noticed when doing parts inventory that I had two ICs with 16 pins. Both had 4052 in the markings. I used the one that had 74HC4052 since that was closer to the description on the parts list. The other had HC4052M on it....
by WB2MSC
18 Nov 2012 20:16
 
Forum: Juma Discussion
Topic: TRX1 74HC4052
Replies: 0
Views: 1563
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