[Elecraft] VCO voltages for 160m band??
G3VVT at aol.com
G3VVT at aol.com
Tue Sep 14 10:42:10 EDT 2004
I needed to open up my K2 serial no. 4168 to tinker with the AGC threshold
setting so took the time to measure what the VCO voltages at R30 were on 160m.
The results are:
1800kHz = 1.68V
2000kHz = 3.83V
On my particular K2 on initial testing the lowest reading VCO voltage
reading came out on 7000kHz rather than 3500kHz so made that the reference setting
at 1.50V. This shifted up 3500KHz to 2.40V and 4000kHz to 6.85V. All still
within the stated goal posts.
As a side issue the optimum AGC threshold seemed to be at 3.70V rather than
the initial 3.80V on this K2. Another item noticed during testing was that
even with the S LO and S HI correctly adjusted for the new threshold the signal
level required for S9 reduced with lower threshold settings. On this K2 with
the preamp off the settings for S9 came out as follows:
AGC threshold V. uV PD for S9.
3.80V 63uV (-71dBm)
3.70V 40uV (-75dBm)
3.60V 25uV (-79dBm)
With the new setting of 3.70V the audible low level band noise from AGC on
to AGC off is just reached the point of no change. This compares with the
initial AGC threshold setting of 3.80v, where there was a small increase in noise
when the AGC was switched off.
Bob, G3VVT
K2 #4168
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