What should Radio TX Power Setting really be? #WSJTX_config #wsjt-x #radio


Ramon S
 

I have been using the WSJT modes since the JT65/JT9 days, until now on FT8, JS8 and I don't think I am doing too bad, given my compromise antenna. Since then, until now, I have not used the WSJT-X panel "Pwr" vertical slider, set at maximum and untouched, and only use my radio's RF power out control, to set my TX power, eg, 5W for WSPR, 20~30W for FT8, JS8.

I recently got a new IC-7610 and I though it might be a good opportunity to review my radio setup and read the latest the online WSJT documentation. These docs do not mention explicitly about the required radio TX power setting, but from what I see in the related io forums, I think they recommend, that the transceiver be set at maximum, 100W in my case, and only use the WSJT-X "Pwr" power slider to go down to your required lower TX output, 5W, 20W.

Does everybody really set their radio to their maximum rated RF power, eg, 100W? Would this not cause undue stress to a radio's finals, if you do a lot of WSJT QSOs?

TIA and 73,
Ramon


Bill Somerville
 

On 20/07/2021 21:44, Ramon S via groups.io wrote:
I have been using the WSJT modes since the JT65/JT9 days, until now on FT8, JS8 and I don't think I am doing too bad, given my compromise antenna. Since then, until now, I have not used the WSJT-X panel "Pwr" vertical slider, set at maximum and untouched, and only use my radio's RF power out control, to set my TX power, eg, 5W for WSPR, 20~30W for FT8, JS8.

I recently got a new IC-7610 and I though it might be a good opportunity to review my radio setup and read the latest the online WSJT documentation. These docs do not mention explicitly about the required radio TX power setting, but from what I see in the related io forums, I think they recommend, that the transceiver be set at maximum, 100W in my case, and only use the WSJT-X "Pwr" power slider to go down to your required lower TX output, 5W, 20W.

Does everybody really set their radio to their maximum rated RF power, eg, 100W? Would this not cause undue stress to a radio's finals, if you do a lot of WSJT QSOs?

TIA and 73,
Ramon
Hi Ramon,

in SSB modes the stress on the PA and PSU is related to the output power, not to the carrier power set on the rig. Personally I would set the Pwr slider to the top (0db attenuation) and use the rig's POWER control as a control of output. I reserve the Pwr slider for if I want to reduce power to less than the POWER control on my rig allows. TBH it is not critical and some setups may work better using the Pwr slider. You could do some tests with a local to see if you can detect any difference.

Here is a post containing a recipe for setting Tx power correctly:

https://wsjtx.groups.io/g/main/message/13890

73
Bill
G4WJS.


Paul Turner
 

Oh man! What have you done? Another round of arguments about low power vs weak signal, ALC settings and blown finals. I can only speak for myself: I run an IC-9700 on 2 metres and have had nearly 1000 QSOs on FT8 mode, all at about 90 watts , which is virtually full power. The Icom rig has good cooling and is happy running the 43% duty cycle of FT8 mode for several minutes at a time. I also have an IC-7300 and have used it at 100 watts on 6 metres in the past although I now have a small amp so only need to run it at about 10 watts. I’m guessing that the IC-7610 has similar cooling and temperature monitoring to my two rigs, so you can probably run close to full “key down” power if that’s what it takes to complete a QSO. Keep the ALC in the “green” (it doesn’t have to be zero) and all will be well.

 

73, Paul G4IJE.

 

 

From: main@WSJTX.groups.io <main@WSJTX.groups.io> On Behalf Of Ramon S via groups.io
Sent: 20 July 2021 21:44
To: main@WSJTX.groups.io
Subject: [WSJTX] What should Radio TX Power Setting really be? #wsjt-x #WSJTX_config #wsjt-x #radio

 

I have been using the WSJT modes since the JT65/JT9 days, until now on FT8, JS8 and I don't think I am doing too bad, given my compromise antenna. Since then, until now, I have not used the WSJT-X panel "Pwr" vertical slider, set at maximum and untouched, and only use my radio's RF power out control, to set my TX power, eg, 5W for WSPR, 20~30W for FT8, JS8.

I recently got a new IC-7610 and I though it might be a good opportunity to review my radio setup and read the latest the online WSJT documentation. These docs do not mention explicitly about the required radio TX power setting, but from what I see in the related io forums, I think they recommend, that the transceiver be set at maximum, 100W in my case, and only use the WSJT-X "Pwr" power slider to go down to your required lower TX output, 5W, 20W.

Does everybody really set their radio to their maximum rated RF power, eg, 100W? Would this not cause undue stress to a radio's finals, if you do a lot of WSJT QSOs?

TIA and 73,
Ramon


Virus-free. www.avast.com


Jim Brown
 

On 7/20/2021 1:50 PM, Bill Somerville wrote:
TBH it is not critical and some setups may work better using the Pwr slider. You could do some tests with a local to see if you can detect any difference.
Remember though that, depending on the rig, audio drive to the rig may be critical to good operation of its ALC. I know this to be true of Elecraft rigs after the K2.

73, Jim K9YC


Michael Black
 

Those Elecraft rigs are pretty unique in that the 4-5 LEDS is 0dB of ALC.  Most all the manuals talk about setting ALC with USB/Phone where you want some ALC to maximize your power for phone.  But too much ALC on most rigs will be the "canary in the coal mine" and overdriving the audio causes harmonics in digital modes.  I've been on the war path (and WA1SXK) for about 3 years now and we have cleaned up the bands from all the harmonics producers.  Rarely see them anymore until after a RTTY contest when new people pop on the air.

You can see how your ALC meter behaves by turning down the power slider in WSJTX to zero, click the Tune and start bringing up the power until the ALC starts to register.  Most rigs will start showing ALC around 90-95% of the rig's power setting so 45-47W when set at 50W and 90-95W when set at 100W.
Elecraft K3/K4 will start showing the ALC meter much lower and will hit the 4-5 bars needed when it's close to 100% of the rig's power.

Mike W9MDB




On Tuesday, July 20, 2021, 05:29:25 PM CDT, Jim Brown <k9yc@...> wrote:


On 7/20/2021 1:50 PM, Bill Somerville wrote:

> TBH it is not critical and some setups may work better using the Pwr
> slider. You could do some tests with a local to see if you can detect
> any difference.


Remember though that, depending on the rig, audio drive to the rig may
be critical to good operation of its ALC. I know this to be true of
Elecraft rigs after the K2.

73, Jim K9YC





Jim Brown
 

On 7/20/2021 3:45 PM, Michael Black via groups.io wrote:
Most rigs will start showing ALC around 90-95% of the rig's power setting so 45-47W when set at 50W and 90-95W when set at 100W.
Elecraft K3/K4 will start showing the ALC meter much lower and will hit the 4-5 bars needed when it's close to 100% of the rig's power.
But don't forget that many rigs, including those Elecraft rigs, have an input gain control, which affects how much drive it takes to be "right."

73, Jim K9YC


Ramon S
 

Thanks for the very informative reply Bill. Much honored...

73, Ramon VE7RVS


Ramon S
 

Thanks for your helpful inputs Paul, Jim, Michael

73, Ramon VE7RVS


Alan G4ZFQ
 

Those Elecraft rigs are pretty unique in that the 4-5 LEDS is 0dB of ALC.
Mike,

Someone posted here saying the K3's ALC indicator shows audio input, then ALC level.
It could be said that the K3's display is more sensitive to lower levels because fundamentally ALC meters all reflect the drive level.

What you posted below is good, it shows how ALC limits maximum power. On some rigs no ALC reading does not mean no output, simply that it is being driven below the power required to operate the ALC.
An ALC reading may comfort an operator but on many rigs working QRP with a zero ALC indication is not a problem.

73 Alan G4ZFQ

You can see how your ALC meter behaves by turning down the power slider in WSJTX to zero, click the Tune and start bringing up the power until the ALC starts to register.  Most rigs will start showing ALC around 90-95% of the rig's power setting so 45-47W when set at 50W and 90-95W when set at 100W.
Elecraft K3/K4 will start showing the ALC meter much lower and will hit the 4-5 bars needed when it's close to 100% of the rig's power.


Michael Black
 

Yes...all that is covered in the paper we wrote for setting up the audio on virtually any rig (nobody has reported that the procedure doesn't work for them).


Mike W9MDB


On Wednesday, July 21, 2021, 12:41:02 AM CDT, Jim Brown <k9yc@...> wrote:


On 7/20/2021 3:45 PM, Michael Black via groups.io wrote:
> Most rigs will start showing ALC around 90-95% of the rig's power
> setting so 45-47W when set at 50W and 90-95W when set at 100W.
> Elecraft K3/K4 will start showing the ALC meter much lower and will hit
> the 4-5 bars needed when it's close to 100% of the rig's power.

But don't forget that many rigs, including those Elecraft rigs, have an
input gain control, which affects how much drive it takes to be "right."


73, Jim K9YC




Gene Horr
 

Rather than "On some rigs no ALC reading does not mean no output, simply that it is being driven below the power required to operate the ALC."

How about "
On rigs no ALC reading does not mean no output, simply that it is being driven in a proper manner to produce a clean, undistorted, easy to understand/decode signal."

73 Gene NG1H


Peter Hall, VK6HP
 

Ramon,

You're probably getting the message that there are a number of ways to get an acceptable RF signal but I believe it's useful to verify - at least initially - the result that you're achieving with a particular setup. The RF output meter is not, a priori, the sole indicator of where the WSJT-X slider should be.  For example, for a given audio interface and/or transceiver sound-card attenuation and gain settings you want to be sure that you're not over-driving the audio stages, one cause of the visible harmonic and other distortion sometimes seen. Similarly, while some ALC systems are fairly benign, the dynamics of others are capable of unduly broadening digital signals.  I find that running the transceiver into a dummy load and monitoring the output with a second receiver and decoder (with spectrum displayed) is invaluable. With most JT modes you have to be very careful of excessive coupling into the monitor receiver but, once that's done, you have the opportunity to familarize yourself, at your leisure, with your computer and radio settings.  You may learn more than you want to know: for example, I can see very low level passive RF intermodulation products in my 630 m antenna, with its very poor, opportunistic ground system incorporating the pool fence.

As far as radio power settings go, in my TS-890S I find the power setting control and the per-band, per-mode power limiting to be useful, especially with an LDMOS amplifier.  The ALC is in the benign class and, while I normally run without ALC showing, signal quality typically remains good right up to the "red" region on the scale.  Your setup is different but the message is that it's not hard to do some very useful monitoring.  Much of the time I use a low-ish cost RSPdx SDR (with one of the antenna input cables terminated), while running the WSJT-X monitoring instance on an old laptop. (The same laptop runs the SDRUno SDR interface and various virtual audio and CAT utilities).

Of course when you believe you have it right there are also remote monitoring options available which, depending on where you live, might be useful.

73, Peter


Ray
 

The ICOM knowledge base available at Icom Global has a document on digital settings.
The power control on most ICOM radios DOES not control power out. It sets the power out threshold.  Max power radio will put out.

Set power out for 100% then adjust slider while watching radio power out meter to set the desired output power.
As long as ALC is in green all is well

No ALC for digital is one of those ham radio myths. It does not apply to constant carrier signals like FT8

FYI on Elecraft radios ALC does not operate until ALC reaches 5 bars. 
Ray
W8LYJ


Bob McGraw - K4TAX
 

Regarding "stress to the radio's finals", what is the radio's duty cycle?   That is the number and procedure and time limit to follow.   As to power settings, each radio has the correct procedure for setting the audio levels and the power settings based on mode.  There are different ways required based on the radio and the data mode.  All of which are correct.  Each brand and model may be quite different.  I find that it is when hams rely on "old ham lore" to do things that issues abound.   Read the manual and follow the procedure is always the better way. 

In my case, following the Elecraft procedure, I set the PWR control on the radio for the desired operating power.   In the case of running barefoot, I set the radio for 100 watts output.   From my take, there is nothing to be saved by running reduced power.   I do run reduced power when driving the amplifier.    I know many hams operate at reduced power with the idea of "saving the tubes or finals".  Measure the efficiency and you'll find that operating at the rated output is the most efficient way. 

73
Bob, K4TAX


Barry Bogart
 

My KX3 sometimes shows NO ALC display, but I am making plenty of FT8 contacts. I use 5 or 10W and mic gain between 40 and 50. When the ALC DOES show anything it can be 4-7 bars with no changes to power or mic gain.


Alan G4ZFQ
 

How about "On rigs no ALC reading does not mean no output, simply that
it is being driven in a proper manner to produce a clean, undistorted, easy to understand/decode signal."
Gene,

Yes! That's what I meant:-)

But you cannot use the K3 like that. It will display "ALC". As Ray says up to 4 bars is not ALC. Are any other or future rigs going to be similar?

Ray,

I guess most power controls work like that, limiting the maximum power but not the minimum. Provided you set the power control so that it limits just above the required power level. Then reduce drive from the computer and advance again so that required level is attained. That should not make the ALC operate regardless of what the indicator says.

73 Alan G4ZFQ


Bob McGraw - K4TAX
 

The Elecraft radios require a different audio adjustment procedure in regard to the levels indicated.  The ALC scale is used to indicate AUDIO LEVEL for the first 4 bars.  The actual Automatic Level Control  {ALC} does not come into effect until after the 5th bar.  The power management system is very different than most radios.  If the Audio Level is not correct, the system will power hunt.   I suggest you GOOGLE  W3FPR and read the correct procedure as found on the left side of his website.   He has an excellent and easy-to-understand written procedure.    If one doesn't do it per his method, be assured you will be incorrect in your setting of an Elecraft radio.......regardless of your results or what you are told.   

"Old Ham Lore" is one of the worst things circulating in the ham community.    It is usually 100% incorrect. 

73
Bob, K4TAX


Brian Morrison
 

On Wed, 2021-07-21 at 08:20 -0700, Ray wrote:
No ALC for digital is one of those ham radio myths. It does not apply to constant carrier signals like FT8

Constant envelope signals are not affected by ALC action unless it causes significant varying phase shifts through the Tx chain for phase modulated modes.

If you have a significant PAPR then you want very little ALC action. It certainly helps if you can see your Tx spectrum in real time.

-- 


Brian  G8SEZ


Bob McGraw - K4TAX
 

The issue I've encountered with many different brands and models of radios is the fact many allow the ALC overshoot when operating at less than rated power.  This is usually caused by the attack timing of the ALC circuit.   Hence if the audio level is set such as to not produce ALC, thus below ALC threshold, no overshoot will exist.   If the audio is above the ALC threshold, then the ALC will momentarily allow excessive power as it is ALC that is controlling output power.   Not all brands or models do this and many have software updates to address the issue. 

Agreed, one should have the ability to monitor the waveform of their signal.  But, unfortunately, many hams today do not own a dummy load or much less a decent signal monitor.    At minimum a ham station today should include, in addition to the radio, (a) a properly rated 50 ohm dummy load, (b) an external power/SWR meter, (c) a means to monitor their own signal.     These items combined will cost less than $300. 

73
Bob, K4TAX

73
Bob, K4TAX


William Smith
 

Hey Bob,

I've been looking for a way to do that since I started playing with FT8, but I can't seem to find an inexpensive way to do this properly, can you point me to some equipment and best practices that'll allow me to do that?

I seem to be doing OK with 'turn the (audio) Pwr up to full power and back off a bit', but I don't know for sure...

Thanks!

73, Willie N1JBJ


On Jul 23, 2021, at 12:30 PM, Bob McGraw - K4TAX <rmcgraw@...> wrote:

(c) a means to monitor their own signal