[Elecraft] K2 Alignment and Test, Part II - No signal on TP3

[Don Wilhelm]

Cameron,

Yes, do get the capacitor for the probe, you will need it for your 
filter alignment even if you do not choose to follow my instructions for 
achieving good K2 Dial Calibration.  Any 10 pF capacitor will do, but 
the axial one is better physically - it fits nicely under the heat 
shrink.  I have a few counter probes with "lumps" because I substituted 
10 pF disc ceramics for the axial capacitors.  Note that I "lose probes" 
often - or more correctly, I leave them in my customer's K2s, so when I 
ger down to a qwuantity of one, I build another from whatever materials 
I have at hand - there is no "magic" it is just a shielded wire with a 
10 pF capacitor at the probe end. BTW, a #14 AWG wire fits the probe 
sockets very nicely if you are inclined toward building your own probe 
tip.  A small amount of grinding/filing will round the tip.

Just jumpering between CB P6 and RF board TP2 or TP3 can lead to 
erroneous readings because any DC present is not being blocked, and that 
can skew the readings.

If you have an external frequency counter, you can move on to the PLL 
range tests and the BFO range tests using the external counter rather 
than the internal one.  Don't worry about the 4 MHZ reference for now 
(it may end up being slightly different than exactly 4.0 MHZ) - just set 
the trimmer slot as indicated by bullet 3.



On 7/3/2012 9:33 PM, Cameron Haines wrote:
> Don,
>
> Great advice. I wasn't able to construct the probe for the frequency counter; missing the capacitor in the kit, either lost it or wasn't included.
>
> I decided to use a external counter instead. Now, if I simply jumper P6 to T2 and T3, I do get a reading, though sure its inaccurate, but reading nonetheless. I will email Elecraft for missing capacitor. In the interim, do you have a suggestion or replacement cap that will give same or near results until part comes in or another work-around?
>
> Cameron
>
>
> ________________________________
>   From: Don Wilhelm <w3fpr at embarqmail.com>
> To: Cameron Haines <camhaines at yahoo.com>
> Cc: David Moorman <dmoorman4 at comcast.net>; "elecraft at mailman.qth.net" <elecraft at mailman.qth.net>
> Sent: Tuesday, July 3, 2012 8:00 PM
> Subject: Re: [Elecraft] K2  Alignment and Test, Part II - No signal on TP3
>   
> Cameron,
>
> Read my last post carefully.  Then tell us whether you are seeing all
> zeros when plugged into TP3 and in CAL FCTR.  If you have all zeros,
> either your probe is bad or your PLL reference is not oscillating.
>
> 73,
> Don W3FPR
>
> On 7/3/2012 8:40 PM, Cameron Haines wrote:
>> Great suggestion. I can hear it a 4Mhz now.. from my Softrock SDR. Wonder why the Freq counters couldn't pick it up however. hmm.
>>
>> Thanks David!
>>
>>
>> ________________________________
>>     From: David Moorman <dmoorman4 at comcast.net>
>> To: Cameron Haines <camhaines at yahoo.com>
>> Cc: "elecraft at mailman.qth.net" <elecraft at mailman.qth.net>
>> Sent: Tuesday, July 3, 2012 7:03 PM
>> Subject: Re: [Elecraft] K2  Alignment and Test, Part II - No signal on TP3
>>    
>> Do you have a receiver you can listen on to see if the oscillator is actually oscillating?
>>
>> Dave K9SW
>>
>>
>>
>> On Jul 3, 2012, at 6:41 PM, Cameron Haines <camhaines at yahoo.com> wrote:
>>
>>> Correction.
>>>
>>>
>>> Hey Guys,
>>>
>>> Well, I am at the part where I need to test the 4 MHz oscillator calibration and ran into a snag. I am not getting anything on two different frequency counters when connected to TP3. Test up to this point have been good. Checked all the components around X1 and all look correct. No error message on startup.
>>>
>>> Any ideas where to go from here?
>>>
>>> Thanks,
>>> Cameron
>>> AE5UZ
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