Greg,
You are right about the bold faced caution on Page 47 and indeed I
waited long before doing the REF CAL, which I did using Method 2 with
the cover closed. However, I am still surprised by the frequency
excursion measured on start up. I did wait a lot longer and calibrated
it using method 2, zero beating it with WWV. This was at ref cal value
of 49,379,611, which is a lot closer to the frequency noted on the sheet
that came with the TCXO - 49,379,964.
With the ref cal set, I have re done VCO CAL and other calibrations.
For now all seems to be as it should be. I have my fingers crossed.
Thanks for your help,
Raj
Greg wrote:
Raj,
You have to read the manual when doing this....Please note this BOLD FACED
caution on page 47.
Before attempting reference calibration,
allow the transceiver to warm up at room
temperature for about 15 minutes (cover on).
Greg
-----Original Message-----
From: Rajiv Dewan, N2RD [mailto:[EMAIL PROTECTED]
Sent: Monday, December 31, 2007 7:38 PM
To: Greg; [EMAIL PROTECTED]
Cc: Elecraft List
Subject: REF OSC Frequency
Great suggestion Greg.
I did not have an appropriate cable to hook into J1 on KEF3. So I
unhooked it from KSYN3 and used the cable to J2 and some clips I had. I
have an HP5343A counter slaved to an HP3801Z GPA stabilized 10MHz
reference. Using this setup, I measured the frequency of the KREF3
(with KTCXO option) at 30 second intervals from cold start. Here is
what I got:
Time min:sec - Frequency 49.xxx.xxx MHz, only the KHz part is noted below:
0:00 - 361.250
0:30 - 361.261
1:00 - 361.306
1:30 - 365:350 big jump!!
2:00 - 377.346 another big jump!!
2:30 - 377.380
3:00 - 377.419
3:30 - 377.471
4:00 - 377.464
4:30 - 377.457
5:00 - 377.507
5:30 - 377.504
6:00 - 377.500
6:30 - 377.490
Turned off and on right away
377.405
Is this normal?
Thanks for the suggestion to check this. I am now going to turn it on,
wait for ten minutes, set the REF CAL and then do the VCO calibration.
PS: I am also forwarding it to the elecraft list as the frequency drift
seems interesting.
Raj, N2RD
Greg wrote:
Raj. You need to do the REF CAL procedure. If you do not have an
accurate
frequency counter for method 1, use method two using USB/LSB to zero beat
WWV. Set the radio to 10.000 MHz or 15.000 MHz. Alternate between USB
and
LSB while listening. Adjust the ref oscillator frequency so that there's
no change in the tones.
What's probably happening is the RO is off by enough that when you use the
narrow filters you are loosing the signal as its outside the passband.
Let me know how it goes. I'll be up for awhile longer.
Greg
-----Original Message-----
From: Rajiv Dewan, N2RD [mailto:[EMAIL PROTECTED]
Sent: Monday, December 31, 2007 6:37 PM
To: Greg
Subject: Re: [Elecraft] K3 #170 CW Filter oddity
It is the default 49.380Mhz.
Raj
Greg wrote:
Raj. What freq is your reference oscillator set to?
Greg
-----Original Message-----
From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] Behalf Of Rajiv Dewan, N2RD
Sent: Monday, December 31, 2007 4:49 PM
To: [EMAIL PROTECTED]; Elecraft List
Subject: Re: [Elecraft] K3 #170 CW Filter oddity
Added note: the change in the DDS frequency occurs by just changing the
filter width or selecting the narrower filters.
Raj
Rajiv Dewan, N2RD wrote:
I have 250Hz, 400Hz and 2.8KHz roofing filters installed. After
update to the latest firm ware I am noticing that the radio goes
really deaf when the 250Hz or the 400Hz filters are used. I have set
the appropriate gain of 4db and 2db, respectively for the 250Hz and
400Hz filters. The FLX FRQ is 0.0 for all. But the deafness is much
more profound than a few dB.
I noticed that the peak in my signal is not where CWT indicates
perfect tune
While I am tuned to a CW signal at 7.02706KHz, I turned on CONFIG:DDS
FRQ and noticed that this frequency changes from 3.581367 MHz to
3.581579 MHz and the radio goes deaf. No change in tuned frequency.
I checked that the FL FREQ for these filters is 0.0. What gives?
Does any of you have the same behavior?
Regards,
Raj, N2RD
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