KX1 low transmit power with KXB3080

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KX1 low transmit power with KXB3080

Bruce Grubbs
I finished the KXB3080 adapter today. Receive seems OK, but transmit power
into a dummy load is only about 0.2 watts on all bands. (It was about 3 watts
with the KXB30.)

I suspect a short somewhere because Q6 gets hot and TX current drain is above
normal at 850 mA, but I'll be darned if I can find it. The voltages at Q1,
Q4, Q4, Q5, and Q are normal.

I;ve also done the mod to increase the L3 windings.

I'll have a fresh look in the morning, but meanwhile, has anybody else seen
this problem?

Thanks es 73,
Bruce
N7CEE

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RE: KX1 low transmit power with KXB3080

Ron D'Eau Claire-2
Bruce, N7CEE, asked:
I finished the KXB3080 adapter today. Receive seems OK, but transmit power
into a dummy load is only about 0.2 watts on all bands. (It was about 3
watts
with the KXB30.)

I suspect a short somewhere because Q6 gets hot and TX current drain is
above
normal at 850 mA, but I'll be darned if I can find it. The voltages at Q1,
Q4, Q4, Q5, and Q are normal.

I;ve also done the mod to increase the L3 windings.

I'll have a fresh look in the morning, but meanwhile, has anybody else seen
this problem?

---------------------

On the LPF1 board, did you check lead L2-1 on the LPF1 board to see if it's
shorted against the solder pad for lead L2-4? L2-1 is the lead that runs
around the end of the LPF1 board to a solder pad right behind it. If you
left the 1/8" on insulation on that lead the instructions called for, you
shouldn't have any trouble there, but if you tinned it up too high and then
pulled the wire tight against the LPF1 board, it can short against that pad.
Just pull it away a bit. One builder who tinned the wire too high took a
very tiny bit of the green wire insulation and threaded it over the L2-1
lead and positioned where it'd prevent the L2-1 lead from being pushed
against that solder pad again.

Ron AC7AC

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Re: KX1 low transmit power with KXB3080

Bruce Grubbs
In reply to this post by Bruce Grubbs
I  found the problem- a solder bridge between pads A and B on the KXB3080
board. Thanks for all the suggestions.

73,
Bruce
N7CEE
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