Hi,
I have a problem quite similar from the first days. This happens
randomly but I found a way to reproduce it as many times as I want, so
I was able to take some measurements.
I never reported it because I though it was something unique to my set
since nobody had reported anything like that.
The symptoms are:
The receiver tunning becames miscalibrated. As an example, when tunning
to a known BC station on 1.485 Mhz its signal appears 0.005307 Mhz
below, and when using a 15.180 Mhz station it appears to be on 15.126044
It seems the 200 Mhz oscillator may start off frequency, because most
of the time the problem appears there is a factor
(-1.0035) that multiplied by the true frequency gives the indicated
one. On some very rare occasions the offset is positive, but I did,t
measured it. I don´t have the means to measure the oscillator frequency
directly.
I can force the problem to appear and dissapear just disconecting the
power to the radio and connecting again one or two seconds later while
looking to the panadapter. In fact, when I suspect the radio beeing
off frequency, I select a MW nearby broadcast station and if it appears
deviated I just unplug and plug again until the frequency is ok.
At the begining I was very puzzled by the loss of calibration until I
found it had nothing to do with the calibration itself neither with the
power supply or version changes and discovered this way of reproducing
the problem and the provisional workaround.
Since I think the problem is the same, maybe Gerald want us to perform
some tests.
73 de Ignacio, EB4APL
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Gerald Youngblood escribió:
Hi Mitch,
This sounds like the 200MHz crystal oscillator has a problem. It sounds
like it starts up at different frequencies in an unrepeatable manner. Is
that correct? Frequency jumps will have nothing to do with cables. Drop me
a direct email with your answer so we can work out the problem. We probably
need to swap out the oscillator.
73,
Gerald
K5SDR
