With my new K2 i have a strange AGC behavior. I cannot detect a difference
between AGC on and off. The voltage at pin 5 U2 is exactly 3.8v after changing
the 8V regulator to a better one. All my earlier k2's had a large increase in
AF when switching off AGC. I possibly made a short between pin
Michael,
Is this new K2 as sensitive (ability to receive weak signals) as the
prior ones? If not, you have have a fault somewhere in the receiver
section.
Do strong signals activate the S-meter bargraph? Try adjusting the
S-meter (CAL S-LO and CAL S-HI) as indicated in the manual, then if
Sjoerd,
Your AGC symptoms sound similar to some of what I found wrong with s/n 3641
when I bought it used. You can find a lot of details in the elecraft
archive - (search for low audio on K2 s/n 3641).
Among other problems, I had a leaky C10 cap in the AGC circuit, upsetting
the AGC control
Sjoerd,
When measuring millivolts some voltmeters are not very accurate. I've seen
them err as much as 40-50 percent. Compare two or three meters and see the
results. Also, some crystals don't put out a pure sine wave making RMS
measurements less acccurate. Look at it on an o'scope if one
Jim, AB0UK wrote:
When measuring millivolts some voltmeters are not very accurate. I've seen
them err as much as 40-50 percent. Compare two or three meters and see the
results. Also, some crystals don't put out a pure sine wave making RMS
measurements less acccurate. Look at it on an
Valc at some point and can tell me if these
values are way off?
Thanks again,
Sjoerd
PE2SVN
-Oorspronkelijk bericht-
Van: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] Namens Sjoerd
Verzonden: dinsdag 29 augustus 2006 22:56
Aan: elecraft@mailman.qth.net
Onderwerp: [Elecraft] K2 AGC problem
Sjoerd,
If you look at the MC1350 data sheet, you will find the AGC characteristics
for operation wiht a 12 volt supply to the chip and that graph indicates
that the gain changes almost linearly from 0 dB to 20dB with an AGC voltage
change from 5 to 6 volts, or 10 dB for a 500 mV change, and the
Aan: Sjoerd; elecraft@mailman.qth.net
Onderwerp: RE: [Elecraft] K2 AGC problem
Sjoerd,
If you look at the MC1350 data sheet, you will find the AGC characteristics
for operation wiht a 12 volt supply to the chip and that graph indicates
that the gain changes almost linearly from 0 dB to 20dB
[mailto:[EMAIL PROTECTED]
Verzonden: woensdag 30 augustus 2006 14:02
Aan: Sjoerd; elecraft@mailman.qth.net
Onderwerp: RE: [Elecraft] K2 AGC problem
Sjoerd,
If you look at the MC1350 data sheet, you will find the AGC
characteristics
for operation wiht a 12 volt supply to the chip
Hello all,
While operating my K2 and switching between bands a lot i noticed my AGC is
a bit strange.
When trying to set the AGC treshold following Don FPR's instructions i find
that the noise level is not changing with the AGC treshold pot with both
preamp on and off. There is a difference in
Hi all,
i would lik evening I reconized a AGC problem on 40m band. My signal
meter shows
S8 to S9 and it sounds like RF-Gain is turned counter clockwise. If
i use ATT to reduce the signal level it does not help. The
signals will drop down but it still sounds like AGC
Someone, Don I think, posted a message this week suggesting that the
background noise with no antenna connected should be the same with AGC
either on or off. I checked mine out of curiosity and discovered that
mine was quieter with AGC on.
Before making adjustments to R1, I thought I'd run
Matt,
At this point, I don't think anything is wrong with your AGC circuit.
Re-check the TEST 3 readings with the RF Gain set to MAX and I believe you
will see readings a bit closer to the Expected values (I think a step is
missing here to tell you to set the RF Gain to max). The 'key' is that
Hi,
My K2 has been working well and I recently noticed that the AGC fast/slow has
little or no effect. I suspect it's been this way for quite some time. I made
some measurements and when performing the AGC tests on U2 (LM833), I get very
close to the expected values for the specified
Hi,
The problem is solved. After thinking about it for a while, and not having the
PIC's data sheet, I wondered if the AGC signal was an open collector / drain
type. It turns out that pin 1 of the resistor network had never been soldered
in by the builder...not me (the builder knows who he
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