[Elecraft] RF Probe again

[Don Wilhelm]

Gary,

You should have signal at U10 pin 1 but you don't - you had a signal at 
the BFO output if I recall correctly, so something is broken between 
those two points.

Since you jumpered the KSB2 headers correctly, leave things that way for 
now.

Set the K2 to TUNE and recheck to be certain you have RF at the 
following points (in order):
U11 pin 6
Q24 gate
TP2
D36 anode (small fragile glass diode on the bottom of the board)
D36 cathode
J11 pin 12
J11 pin 7
U10 pin 1

That is the entire path between the BFO and the transmit mixer input, 
and you should be able to locate the point where the signal disappears.

73,
Don W3FPR


Gary Montalbine wrote:
> Don Wilhelm wrote:
>> Gary does not work weekends, and you can likely have it isolated by then.
>>
>> If you have no output from U10-4, then how about the input at pin 1? 
>> That should be the BFO signal fed to the transmit mixer. (you do have 
>> the KSB2 plugged in correctly do you not?).
> 
> Pin 1 also reads 0. Per the troubleshooting instructions the KSB2 was 
> removed. I installed temporary jumper pins between 1 & 3 of J9 and J10 
> and installed a .001mf cap between pins 7 & 12 of J11. I can reinstall 
> KSB2 if you think it will help.
> 
>   The only other signal that
>> must be present is the TX VFO which should have at least 70 mV RF on 
>> U10 pin 6.
> 
> I have .16V
> 
>   You must be in TUNE or otherwise keydown to get RF to U10-1.
> 
> Tried both.
>>
>> If you have RF at both U10-1 and U10-6, you shoudl also have RF at 
>> U10-4.  Check the DC voltage at pin 8 (it will only be present during 
>> TUNE or other transmit periods).
> 
> Pin 8 voltage is 6V in tune.
> 
> Thanks,
> 
> Gary WA4SZI
>>
>> 73,
>> Don W3FPR
>>
>> Gary Montalbine wrote:
>>> Basic problem was engage mind before typing. High DC voltage at U8 
>>> and no RF voltage at pin 4 of U10. Low RF voltage at pin 6 of U9. 
>>> Wanted to make sure my RF probe was good before continuing. It has 
>>> been many years since I have messed with electronic circuits.I may be 
>>> back at the Novice level. Would this be the appropriate forum to 
>>> address my transmitting problems or should I bother Gary?
>>>
>>> I appreciate everybodys help thus far.
>>>
>>> Gary, WA4SZI
>>>
>>> K2 #1009
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