Re: Low power output on ubitx

Conrad San Diego

Hi Mike I had the same problem.  I checked Q90 and found E & B are shorted. I replaced 2N3904 with a regular type transistor Instead of the SMD type. I get 30 W but I tuned it down to 15 W.

On Fri, Mar 16, 2018, 17:20 Mike R. <ubitx@...> wrote:
First post - be gentle :)
I have been playing around with the ubitx for about a week now. Pretty cool radio and I like the idea of modifying the software.
Installed Ian's version of the software v1.04 and even added a menu entry on my own to display the current version which normally only appears at power up. Still have a ways to go in fully understanding the software for the rig.
To the point...I was listening to some FT8 the other night and enjoying the decoding on the computer screen from the ubitx. I thought it might be nice to see if I could transmit. So, I connected a dummy load and wattmeter to see if the rig was putting out power. I tried CW first.
I had VERY low power out, in the range of milliwatts.
The numbers:
Frequency: 7.150, antenna connected to a dummy load.
Power supply set to 12.5 volts. Using a key to send CW.
Output was nil on 40m. Didn't make the meter move on the WM-1.
So, I did the bias adjustment thing that everyone says to not do. Adjusted the bias for the 510's at 100ma each and then set RV3 max clockwise (how it was received, actually).
Output on 40M was about 400mw after adjusting the bias and RV3.
Started to dig into Glenn's post where he made measurements of the PA section. Everything was nominal to his
numbers except for the collector voltages on Q92-93 and 96-97 where they were 12V vs. the 2.8v he measured.
I get 12v on the "TX" side of R961 and 11V on the junction of R961 and C92.
Receive current is about 160ma and transmit current is around 720ma for an output of about 400mw.
I'm thinking there is something amiss with T10.
Any comments for anyone that has had the same issue and found a resolution?
Thanks, Mike W1USN

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