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QDX firmware minor release 1_01b #qdx

 

Hi all

A potential new failure mode was discovered, wherein if you happened to accidentally enter a grossly incorrect calibration reference frequency in the configuration screen, you could burn two of the BS170s. For example if you meant to enter 25,000,002 but accidentally wrote 2,500,002 then the Si5351A configuration could not succeed, resulting in a DC output on the Si5351A pins, putting one pair of BS170s 100% on (high current) and the other pair 100% off (no current).?

To resolve this 1_01b now does a check to make sure that the entered frequency is 25MHz?+/- 1kHz. Outside this range, it would be ignored.?

This is a minor non-essential upgrade, just another protection against a possible?failure mode.?

73 Hans G0UPL
 

hi Hans,

I burned two of the BS170 without making any action in the Software. I run about 25 QSOs on 40m an 30m . Than I changed to 20m using a Magnetic Loop Antenna. Before transmitting I tuned that antenna with my TS940 to get a good SWR. Output at first was 5Watts (12 V Version, I got about 13V with my Lead Battery). After 10 CQ callings I smelled smoke.

Before I started with 20m , I put the QDX in the metal case. FOr 30 and 40m the QDX was not enveloped. I had to cut a part of the case to get my QDX inside (A SMD part was too vclosed to the case, not possible to slide to the end.

Two of the BS170 are destroyd. I replaced all 4 and I still can receive, but not Power Output. I can hear my? transmitting? FT8 Signal with the TS940 and also I can measure a Voltage with the RF probe on all new BS170, but not the same (25V to 40V).

IC5 is very warm, almost hot. Normal ?

C32 ode C34? damaged ? Any solution ? How can I test, if the IC5 is o.K. ? C32 and C34 ?

72 de Matt, DL1SER
 

IC5 is very warm, almost hot. Normal ?
Matt,

I have never checked but there should be no reason for it to get hot.
Have you checked the voltages on IC5?
Someone has reported damage to IC5 after a similar BS170 failure.

(Does your magnetic loop tuning ever change? When I used one it varied especially in damp weather.)

73 Alan G4ZFQ
 

Just adding some unscientific anecdotal evidence as I too experienced catastrophic failure of a BS170 while transmitting on 20m.? Same situation, lots of QSOs on 40m, switched over to 20m and heard a pop midway through the first transmission.??

Now I may also have been doing some other foolish things like trying to power it with a DC-DC buck converter (which to be fair didn't seem to be a problem on 40m), and I have not tuned my 20m dipole lately so it could well be there was lots of SWR.? I've since built a linear regulator and I'll check the antenna, but I'm still wary of trying 20m again.

Fortunately I was able to replace all 4 transistors and I seem to be back in business at full power.

Dennis

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