Hi All
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QDX? High Band Rev 5? board, Firmware 1.07.? Wound for 9V, supply at 7.5V
This is my 3rd QDX and 1st high band version.? RX is good.? TX has zero RF out on all bands.? Status LED suggests TX is working when selected by "Tune", "Enable TX" or "Teminal Emulator", suggesting audio levels are OK.? Current draw increases a bit as expected (Standby/RX 150 mA, TX 240mA.? Out of enclosure, no sign of magic smoke but getting hot in region of TXCO.? At high magnification there are indications of damage to IC11, MS5351M (tiny puncture wound & small fluid leak)
Assuming IC11 has failed and needs replacing, can I expect and be prepared for other component failures? I suspect brief transmission into open circuit as cause. BS170 show no obvious damage.
Anyone any experience sourcing MS5351M?? I can only see it direct from manufacturer in China.? I do still have one or two of the old Si chips somewhere at my other shack (along with a load of BS170 which I got before Farnell were surcharging small orders).
I thought Hans did mention that the MS chip had slightly better performance at cost of small increase in current draw.? Unsure whether to try to buy now and get the job done or wait a month til I'm back in the other location and can use the Si chip. I had been hoping to take advantage of the recent good conditions on the higher bands from here.? Testing my patieince and commonsense!
Any thoughts/guidance welcome.? Thanks.
73 Mike
