Joe Subich, W4TV-4 wrote:
Older (tube) radios did not have power level controls. They
were operated at their design power and ALC reduced the gain
to prevent overdriving the final amplifiers.
Later radios added additional comparators to the ALC system
to sense absolute power in
Kenneth A. Christiansen-2 wrote:
+If the filter response varies across the passband, which it does, the ALC
+will vary the amount of gain used to try to keep the RF level to the
amount
+it is set at, whether the signal is being generated near the edge of the
+passband or at the center.
Joe Subich, W4TV wrote:
Absolutely not! When conventional rigs are generating ALC
their final amplifiers are ALREADY in compression and they
are generating IMD in the PSK31 signal.
A bit sweeping, Joe. Surely any sane engineer would put the onset of
system ALC at a level *before* the
Subject: Re: [Elecraft] K3 pwr out on digimodes
Joe Subich, W4TV-4 wrote:
This is your fundamental misunderstanding of ALC. Traditional
ALC does NOT (and can not) increase gain - it can only DECREASE
gain to bring the grid/base/gate current down to the level at
which the final
Peter,
I don't read your message before sending my very long mine but i
totally agree with you!
I can imagine that digimodes software generate ± complex audio signals,
then we can
adjust this audio level to allow TX chain, including PA, to work in a
linear zone.
(I admit that we should be
Pete F5VNB wrote:
Joe Subich, W4TV wrote:
Absolutely not! When conventional rigs are generating ALC
their final amplifiers are ALREADY in compression and they
are generating IMD in the PSK31 signal.
A bit sweeping, Joe. Surely any sane engineer would put the onset of
system ALC at a
Peter Connors, F5VNB wrote:
Absolutely not! When conventional rigs are generating ALC
their final amplifiers are ALREADY in compression and they
are generating IMD in the PSK31 signal.
A bit sweeping, Joe. Surely any sane engineer would put the onset of
system ALC at a level *before* the PA
Ian White GM3SEK wrote:
A sane engineer surely would; but the huge majority of transceivers are
trying to use the ALC loop for too many different functions including
gain levelling between bands, peak limiting and also power control.
[snip]
I seem to have read this before -
+If the filter response varies across the passband, which it does, the ALC
+will vary the amount of gain used to try to keep the RF level to the amount
+it is set at, whether the signal is being generated near the edge of the
+passband or at the center. This is important to the PSK31 operator who
[mailto:elecraft-boun...@mailman.qth.net] On Behalf Of Peter
Connors, F5VNB
Sent: Saturday, January 17, 2009 4:34 AM
To: elecraft@mailman.qth.net
Subject: Re: [Elecraft] K3 pwr out on digimodes
Joe Subich, W4TV wrote:
Absolutely not! When conventional rigs are generating ALC
On Jan 17, 2009, at 1/173:00 AM, hb9ari wrote:
I can imagine that digimodes software generate ± complex audio
signals,
then we can adjust this audio level to allow TX chain, including
PA, to work in a
linear zone.
Out of the common HF digital modes, I believe that BPSK31 and
...@mailman.qth.net
[mailto:elecraft-boun...@mailman.qth.net] On Behalf Of Julian, G4ILO
Sent: Saturday, January 17, 2009 10:27 AM
To: elecraft@mailman.qth.net
Subject: Re: [Elecraft] K3 pwr out on digimodes
Ian White GM3SEK wrote:
A sane engineer surely would; but the huge majority
Joe Subich, W4TV wrote:
If you want to be able to click to tune
without manually adjusting power levels get a Flex-5000 or
a transmitter that uses on frequency RF generation.
Would a possible solution be 'split' operation using VFOA to 'read' an
ssb passband via the sound card while
Julian, G4ILO wrote:
I seem to have read this before - perhaps in one of your RadCom
columns?
Yes; the first discussions were here, sometime around March 2008.
Then you saw it again in my May 2008 column in Radcom, although that
article was specifically about the deficiencies of normal
Joe Subich, W4TV wrote:
Older (tube) radios did not have power level controls. They
were operated at their design power and ALC reduced the gain
to prevent overdriving the final amplifiers.
This is true.
I used to run PSK31 with a Kenwood TS-520. No power control on that rig
and the
Benson,
I've done some measurements some time ago with my K3 #1212 and i had the
following values:
K3 power set to 20W, f=7.040MHz 25W 50 Ohms dummy load
MCE/WeinschelLP-100A Wattmeter
mode USB 1 kHz sine audio at rear line-input, level adjusted to have
the desired ALC bar
Rudolf, the problem is not one associated with the accuracy of the K3
meter, but one of the ALC being fairly slack with the end result that
a fluctuating audio input from speech or from a sound card on many data
modes results in widely varying power, unfortunately often exceeding the
level set by
Thanks for this table. It appears we should be aiming for 2-3 bars not 6!
Ideally, everyone will have an accurate RF power meter in circuit.
If you know the PA current, which you can read accurately and the voltage
which can also be read, you can calculate your input power. All you then
need
Dave,
I followed the problem you described on the group and this is the reason
i do some measurements around the power output because i was a little
bit anxious!
At the beginning, my only 2 ham references were my MiniVNA output
(calibrated at my office at -2.04 dBm , 7.040MHz with 50 Ohms load)
hb9ari wrote:
Benson,
I've done some measurements some time ago with my K3 #1212 and i had the
following values:
K3 power set to 20W, f=7.040MHz 25W 50 Ohms dummy load
MCE/WeinschelLP-100A Wattmeter
mode USB 1 kHz sine audio at rear line-input, level adjusted to have
the
Further to what I wrote, I have just noted that the power output in DATA A
still varies though only by about 2dB across the passband even when the
audio input is increased to drive 4-5 bars of ALC.
In SSB mode, with the audio level adjusted to no more than 2 bars of ALC,
and CMP reduced to zero,
- Original Message -
From: Julian, G4ILO julian.g4...@gmail.com
I believe that when the K3 was released a year ago, the DATA A mode was
identical in behavior to SSB...
It was *very* flat, I haven't used my K3 for the last year other than to add
HRD support. I've been using my
The K3 suggested ALC level for digital modes is *4* bars. The 6 bar
indication is for SSB (actually listed as 5-7 bars).
According to the K3 FAQ page - when the indication is at 5 bars, the DSP
ALC is just being tickled. For data modes, ALC action is not
desirable, thus the 4 bar
Don Wilhelm-4 wrote:
The K3 suggested ALC level for digital modes is *4* bars. The 6 bar
indication is for SSB (actually listed as 5-7 bars).
According to the K3 FAQ page - when the indication is at 5 bars, the DSP
ALC is just being tickled. For data modes, ALC action is not
: elecraft-boun...@mailman.qth.net
[mailto:elecraft-boun...@mailman.qth.net] On Behalf Of Julian, G4ILO
Sent: Friday, January 16, 2009 8:53 AM
To: elecraft@mailman.qth.net
Subject: Re: [Elecraft] K3 pwr out on digimodes
Don Wilhelm-4 wrote:
The K3 suggested ALC level for digital
Joe Subich, W4TV-4 wrote:
the purpose of ALC is not to control the
shape of the passband across the SSB filter it is to prevent a
SSB signal in total from overdriving the power amplifiers.
I agree with you. As applied to a voice SSB signal or even a wideband data
mode that is
] K3 pwr out on digimodes
Joe Subich, W4TV-4 wrote:
the purpose of ALC is not to control the
shape of the passband across the SSB filter it is to prevent a
SSB signal in total from overdriving the power amplifiers.
I agree with you. As applied to a voice SSB signal
Joe W4TV wrote:
Closed loop power controls are not appropriate to SSB systems because time
constants sufficient to maintain constant power across the
IF passband for digital operation would result in frequency
dependent clipping and/or compression in voice operation.
Most digimode programs
Joe Subich, W4TV-4 wrote:
This is your fundamental misunderstanding of ALC. Traditional
ALC does NOT (and can not) increase gain - it can only DECREASE
gain to bring the grid/base/gate current down to the level at
which the final amplifier is not being overdriven. DSP based
ALC is
Leigh L. Klotz Jr WA5ZNU wrote:
Most digimode programs include a tune button which outputs a tone at the
selected output; psk's idle is a simple two-tone. One option (and I
expressed this a year or so ago to the Elecraft folks) would be to offer
an IMD calibration at the IF level for a
, January 16, 2009 2:18 PM
To: li...@subich.com
Cc: 'Julian, G4ILO'; elecraft@mailman.qth.net
Subject: Re: [Elecraft] K3 pwr out on digimodes
Joe W4TV wrote:
Closed loop power controls are not appropriate to SSB
systems because
time constants sufficient to maintain constant power across
: elecraft-boun...@mailman.qth.net
[mailto:elecraft-boun...@mailman.qth.net] On Behalf Of Julian, G4ILO
Sent: Friday, January 16, 2009 4:40 PM
To: elecraft@mailman.qth.net
Subject: Re: [Elecraft] K3 pwr out on digimodes
Joe Subich, W4TV-4 wrote:
This is your fundamental
I do not have the benefit of an external wattmeter at the moment and
frequently use digital modes, esp. JT65A. Assuming I want to transmit 25
W or less, if I have PWR set at 25 and adjust the mic gain for ALC just
under 1 bar (basically just until one bar disappears), approximately how
much
Benson-2 wrote:
I do not have the benefit of an external wattmeter at the moment and
frequently use digital modes, esp. JT65A. Assuming I want to transmit 25
W or less, if I have PWR set at 25 and adjust the mic gain for ALC just
under 1 bar (basically just until one bar disappears),
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