[Elecraft] K2 IF Amp

[Peter]

Don,

I used a scope to find the peak tuning the VFO. I re-soldered all pads in 
that area. In the meantime I checked the crystal filter.
I injected a signal to J9 (W2) of 4913.72 kHz (I get the peak at this freq.) 
about 800 mV and got about 500 mV out at J10 (W3).
On the scope the signal shape at W3 looks very bad, at W2 it´s much better 
and at pin 4 U12 it`s clean, but I thinks that is normal.

73
Peter, DF8BB


----- Original Message ----- 
From: "Don Wilhelm" <w3fpr at embarqmail.com>
To: "Peter" <df8bb at teleos-web.de>
Cc: <Elecraft at mailman.qth.net>
Sent: Monday, March 02, 2009 1:19 PM
Subject: Re: [Elecraft] K2 IF Amp


> Peter,
>
> The 1.4 volts at W2 is good, but you should have more signal out of the 
> crystal filter (at W3).
> Are you certain you peaked the signal in the filter by tuning the VFO? 
> The tuning will be very sharp.
> Re-flow the solder on the crystals, the varactors, RP4 and RP5.
>
> Obtain the proper signal out of the filter before drawing any conclusions 
> about the IF amp or any stages that follow.
>
> 73,
> Don W3FPR
>
> Peter wrote:
>> Hi I´m just doing receiver signal tracing using the Elecraft RF probe. 
>> Coming to measure signal at U12 there are 300mV at pin 4 but only 1 or 2 
>> mV at pin 8 no change if I increase the generator input or RF gain to 
>> max. The same with U11 at pin 1, when I increase RF Gain I get n o more 
>> than 30mV at pin 5 of U11. Across the crystal filter I get only about 100 
>> mV at W3 with 1,4 V at W2. Is that a matter of the filter circuit or the 
>> IF amp MC1350. Thanks for any help...
>>
>> 73
>> Peter, DF8BB (K2 6437)
>>
>