Gordon,
That amount of RF is about (with 800mV on the Q5 collector).
I am close to agreeing with you about a bad Q6, but do the checks I
mentioned anyway.
If you do find out Q6 is the culprit -- if this is a kit less than 1
year old, contact support@elecraft and ask for a replacement.
If more than 1 year old (or you were not the original purchaser), it is
not under warranty and you will have to pay for the part - contact the
sales office to do that (make sure you have the part number handy).
They will need payment information. The phone number is 831-763-4211.
The minimum parts order is $5. Get a replacement for Q10 at the same
time, just in case.
73,
Don W3FPR
On 3/4/2018 3:39 PM, Gordon LaPoint wrote:
Don,
I have about 220mv P-P on the base of Q6. I'm off to check all
the components in the base ckt of Q6, with just DC on the collector.
This is in Tune with the Power out set to 2W.
Thanks,
Gordon - N1MGO
On 3/4/2018 3:10 PM, Don Wilhelm wrote:
Gordon,
It is doubtful (but possible) that Q6 is bad. Did it overheat when
you powered up? - if it did, you would most likely have seen a wisp of
smoke.
How large is the signal at the base of Q6 when you have 800mV P-P on
the collector of Q5?
The base voltage on Q6 is higher than normal, it should be around 1.1
volts. I would suggest you check all components in the base circuit
of Q6 first.
73,
Don W3FPR
On 3/4/2018 2:26 PM, Gordon LaPoint wrote:
I'm building a K2 kit and I have a problem. I'm starting the
Alignment and Test, Part III on page 77-78. I have no rf out. I
have followed the rf through the tx chain and have a good signal at
(RF board) Q5 collector (800mv P-P) using a 400Mhz scope. I have a
signal on Q6 base, but nothing on the collector. The DC voltage (in
TX) at Q6 is 12.0 Collector, 1.8VDC base and 0 on emitter. I don't
see anything wrong DC wise, is it likley that Q6 is bad? What else
should I look for? With the radio off the R at Q6 emitter to ground
is 1.8ohms, that looks normal, so I don't have any current flow in
Q6, it looks like.
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