locked Duty cycle question


d_ziolkowski
 

Hello all=

We have all been educated that due to the high duty cycle of FT8, it is wise to not run full power of you rig to avoid burning up the finals. 

My question relates to the effect of the transmitted bandwidth, which in FT8 is 50HZ, has on the actual power loading of the finals. 

Since when transmitting a 50Hz signal via a transmitter capable of about 2Khz or so, would this , in effect , very lightly load the finals, even at full power?

Thanks

Dan KC2STA


Arnold Lausevich <nk9o@...>
 

Thats why I run my amp at 50% because of the duty cycle especially during a contest.   Thats the exception than the normal operating practice of just running my rig.  Also I run at 50% usually and thats more than adequate for FT8 in 90% of my contacts.

On Thursday, August 13, 2020, 2:14:11 PM CDT, d_ziolkowski <dan.ziolkowski@...> wrote:


Hello all=

We have all been educated that due to the high duty cycle of FT8, it is wise to not run full power of you rig to avoid burning up the finals. 

My question relates to the effect of the transmitted bandwidth, which in FT8 is 50HZ, has on the actual power loading of the finals. 

Since when transmitting a 50Hz signal via a transmitter capable of about 2Khz or so, would this , in effect , very lightly load the finals, even at full power?

Thanks

Dan KC2STA


Hasan Schiers N0AN
 

Dan,
No. FT8 is virtually 100% duty cycle. It has little to do with transmitted bandwidth.
73, N0AN
Hasan



On Thu, Aug 13, 2020 at 2:14 PM d_ziolkowski <dan.ziolkowski@...> wrote:
Hello all=

We have all been educated that due to the high duty cycle of FT8, it is wise to not run full power of you rig to avoid burning up the finals. 

My question relates to the effect of the transmitted bandwidth, which in FT8 is 50HZ, has on the actual power loading of the finals. 

Since when transmitting a 50Hz signal via a transmitter capable of about 2Khz or so, would this , in effect , very lightly load the finals, even at full power?

Thanks

Dan KC2STA


W1EL Eric
 

Power out = power out, regardless of bandwidth.

 

Best, Eric (W1EL)

 

From: main@WSJTX.groups.io <main@WSJTX.groups.io> On Behalf Of d_ziolkowski
Sent: Thursday, August 13, 2020 15:14
To: main@WSJTX.groups.io
Subject: [WSJTX] Duty cycle question

 

Hello all=

We have all been educated that due to the high duty cycle of FT8, it is wise to not run full power of you rig to avoid burning up the finals. 

My question relates to the effect of the transmitted bandwidth, which in FT8 is 50HZ, has on the actual power loading of the finals. 

Since when transmitting a 50Hz signal via a transmitter capable of about 2Khz or so, would this , in effect , very lightly load the finals, even at full power?

Thanks

Dan KC2STA


careyfisher@...
 

15 seconds On, 15 seconds Off, looks like a 50% duty cycle to me.
73, Carey, WB4HXE

On Thu, Aug 13, 2020 at 3:42 PM W1EL Eric <elowell@...> wrote:

Power out = power out, regardless of bandwidth.

 

Best, Eric (W1EL)

 

From: main@WSJTX.groups.io <main@WSJTX.groups.io> On Behalf Of d_ziolkowski
Sent: Thursday, August 13, 2020 15:14
To: main@WSJTX.groups.io
Subject: [WSJTX] Duty cycle question

 

Hello all=

We have all been educated that due to the high duty cycle of FT8, it is wise to not run full power of you rig to avoid burning up the finals. 

My question relates to the effect of the transmitted bandwidth, which in FT8 is 50HZ, has on the actual power loading of the finals. 

Since when transmitting a 50Hz signal via a transmitter capable of about 2Khz or so, would this , in effect , very lightly load the finals, even at full power?

Thanks

Dan KC2STA




--
Carey Fisher


--
73, Carey, WB4HXE


Joe WB9SBD
 

How narrow is a dead carrier? a LOT smaller than 50 hz, so how long can your rig like a CW Key be pressed down and held?

Joe WB9SBD

The Original Rolling Ball Clock
Idle Tyme
Idle-Tyme.com
http://www.idle-tyme.com

On 8/13/2020 2:14 PM, d_ziolkowski wrote:

Hello all=

We have all been educated that due to the high duty cycle of FT8, it is wise to not run full power of you rig to avoid burning up the finals. 

My question relates to the effect of the transmitted bandwidth, which in FT8 is 50HZ, has on the actual power loading of the finals. 

Since when transmitting a 50Hz signal via a transmitter capable of about 2Khz or so, would this , in effect , very lightly load the finals, even at full power?

Thanks

Dan KC2STA


    


Joe WB9SBD
 

60 minutes on, 60 minutes off is then also 50% duty cycle?

Joe WB9SBD

The Original Rolling Ball Clock
Idle Tyme
Idle-Tyme.com
http://www.idle-tyme.com

On 8/13/2020 2:58 PM, careyfisher@... wrote:

15 seconds On, 15 seconds Off, looks like a 50% duty cycle to me.
73, Carey, WB4HXE

On Thu, Aug 13, 2020 at 3:42 PM W1EL Eric <elowell@...> wrote:

Power out = power out, regardless of bandwidth.

 

Best, Eric (W1EL)

 

From: main@WSJTX.groups.io <main@WSJTX.groups.io> On Behalf Of d_ziolkowski
Sent: Thursday, August 13, 2020 15:14
To: main@WSJTX.groups.io
Subject: [WSJTX] Duty cycle question

 

Hello all=

We have all been educated that due to the high duty cycle of FT8, it is wise to not run full power of you rig to avoid burning up the finals. 

My question relates to the effect of the transmitted bandwidth, which in FT8 is 50HZ, has on the actual power loading of the finals. 

Since when transmitting a 50Hz signal via a transmitter capable of about 2Khz or so, would this , in effect , very lightly load the finals, even at full power?

Thanks

Dan KC2STA




--
Carey Fisher


--
73, Carey, WB4HXE

    


Frank Donovan
 

Try with on your radio and let us know how it goes...



From: "Joe WB9SBD" <nss@...>
To: main@WSJTX.groups.io
Sent: Thursday, August 13, 2020 8:32:49 PM
Subject: Re: [WSJTX] Duty cycle question

60 minutes on, 60 minutes off is then also 50% duty cycle?

Joe WB9SBD

The Original Rolling Ball Clock
Idle Tyme
Idle-Tyme.com
http://www.idle-tyme.com

On 8/13/2020 2:58 PM, careyfisher@... wrote:
15 seconds On, 15 seconds Off, looks like a 50% duty cycle to me.
73, Carey, WB4HXE

On Thu, Aug 13, 2020 at 3:42 PM W1EL Eric <elowell@...> wrote:

Power out = power out, regardless of bandwidth.

 

Best, Eric (W1EL)

 

From: main@WSJTX.groups.io <main@WSJTX.groups.io> On Behalf Of d_ziolkowski
Sent: Thursday, August 13, 2020 15:14
To: main@WSJTX.groups.io
Subject: [WSJTX] Duty cycle question

 

Hello all=

We have all been educated that due to the high duty cycle of FT8, it is wise to not run full power of you rig to avoid burning up the finals. 

My question relates to the effect of the transmitted bandwidth, which in FT8 is 50HZ, has on the actual power loading of the finals. 

Since when transmitting a 50Hz signal via a transmitter capable of about 2Khz or so, would this , in effect , very lightly load the finals, even at full power?

Thanks

Dan KC2STA




--
Carey Fisher


--
73, Carey, WB4HXE

    





Joe WB9SBD
 

exactly!

On 8/13/2020 3:35 PM, Frank Donovan wrote:

Try with on your radio and let us know how it goes...


From: "Joe WB9SBD" <nss@...>
To: main@WSJTX.groups.io
Sent: Thursday, August 13, 2020 8:32:49 PM
Subject: Re: [WSJTX] Duty cycle question

60 minutes on, 60 minutes off is then also 50% duty cycle?

Joe WB9SBD

The Original Rolling Ball Clock
Idle Tyme
Idle-Tyme.com
http://www.idle-tyme.com

On 8/13/2020 2:58 PM, careyfisher@... wrote:
15 seconds On, 15 seconds Off, looks like a 50% duty cycle to me.
73, Carey, WB4HXE

On Thu, Aug 13, 2020 at 3:42 PM W1EL Eric <elowell@...> wrote:

Power out = power out, regardless of bandwidth.

 

Best, Eric (W1EL)

 

From: main@WSJTX.groups.io <main@WSJTX.groups.io> On Behalf Of d_ziolkowski
Sent: Thursday, August 13, 2020 15:14
To: main@WSJTX.groups.io
Subject: [WSJTX] Duty cycle question

 

Hello all=

We have all been educated that due to the high duty cycle of FT8, it is wise to not run full power of you rig to avoid burning up the finals. 

My question relates to the effect of the transmitted bandwidth, which in FT8 is 50HZ, has on the actual power loading of the finals. 

Since when transmitting a 50Hz signal via a transmitter capable of about 2Khz or so, would this , in effect , very lightly load the finals, even at full power?

Thanks

Dan KC2STA




--
Carey Fisher


--
73, Carey, WB4HXE






    


JP Tucson, AZ
 

Nope! It is 100% for 13 seconds out of 30...  an overall 43% true duty cycle.

AND... it will warm up your finals unless you mitigate the extra heat; using extra fans across the PA heat sink/case will do the trick.

I went on an outing here in Arizona several days back... 108 degrees... I modified a small cooler with 2 holes, one a smaller air entry with filter (to prevent dust intrusion, and a second outlet hole - 3 inches & with a hose tube & blower with the outlet right on to the back of the radio.  Inside the small cooler are 12 "blue ice" solid blocks that the air goes through & around... they were frozen to zero degrees  F !   The air to the radio was 55 degrees. The temp probe on the heat sink never rose above 69. That's 40 degrees less than the outdoor air temp.  You can certainly store more blue ice blocks in another unmodified cooler for hour upon hours & swap those in once the ones in operation can't keep the tube exit air below 75 or 80; I ran mine for 3.5 hours and at the end it was still no higher than 69 degrees.  We ran out of endurance in the desert heat before the batteries & blue ice did.  
 

73 - John - N7GHZ


On Thu, Aug 13, 2020, 12:28 PM Hasan Schiers N0AN <hbasri.schiers6@...> wrote:
Dan,
No. FT8 is virtually 100% duty cycle. It has little to do with transmitted bandwidth.
73, N0AN
Hasan



On Thu, Aug 13, 2020 at 2:14 PM d_ziolkowski <dan.ziolkowski@...> wrote:
Hello all=

We have all been educated that due to the high duty cycle of FT8, it is wise to not run full power of you rig to avoid burning up the finals. 

My question relates to the effect of the transmitted bandwidth, which in FT8 is 50HZ, has on the actual power loading of the finals. 

Since when transmitting a 50Hz signal via a transmitter capable of about 2Khz or so, would this , in effect , very lightly load the finals, even at full power?

Thanks

Dan KC2STA



d_ziolkowski
 

But--- a CW signal is 100% carrier. 

FT8 is USB , little to no carrier.

Think AM vs SSB.

Dan KC2STA



On Thu, Aug 13, 2020 at 4:29 PM Joe WB9SBD <nss@...> wrote:
How narrow is a dead carrier? a LOT smaller than 50 hz, so how long can your rig like a CW Key be pressed down and held?

Joe WB9SBD

The Original Rolling Ball Clock
Idle Tyme
Idle-Tyme.com
http://www.idle-tyme.com

On 8/13/2020 2:14 PM, d_ziolkowski wrote:
Hello all=

We have all been educated that due to the high duty cycle of FT8, it is wise to not run full power of you rig to avoid burning up the finals. 

My question relates to the effect of the transmitted bandwidth, which in FT8 is 50HZ, has on the actual power loading of the finals. 

Since when transmitting a 50Hz signal via a transmitter capable of about 2Khz or so, would this , in effect , very lightly load the finals, even at full power?

Thanks

Dan KC2STA


    




--
Dan Ziolkowski KC2STA
SKCC #4290T
Ubuntu LINUX


Frank Donovan
 

Don't try that on the east coast...  The humidity in our air would quickly
fill the cooler with water!



From: "JP Tucson, AZ" <samcat88az@...>
To: main@wsjtx.groups.io
Sent: Thursday, August 13, 2020 8:42:00 PM
Subject: Re: [WSJTX] Duty cycle question

Nope! It is 100% for 13 seconds out of 30...  an overall 43% true duty cycle.

AND... it will warm up your finals unless you mitigate the extra heat; using extra fans across the PA heat sink/case will do the trick.

I went on an outing here in Arizona several days back... 108 degrees... I modified a small cooler with 2 holes, one a smaller air entry with filter (to prevent dust intrusion, and a second outlet hole - 3 inches & with a hose tube & blower with the outlet right on to the back of the radio.  Inside the small cooler are 12 "blue ice" solid blocks that the air goes through & around... they were frozen to zero degrees  F !   The air to the radio was 55 degrees. The temp probe on the heat sink never rose above 69. That's 40 degrees less than the outdoor air temp.  You can certainly store more blue ice blocks in another unmodified cooler for hour upon hours & swap those in once the ones in operation can't keep the tube exit air below 75 or 80; I ran mine for 3.5 hours and at the end it was still no higher than 69 degrees.  We ran out of endurance in the desert heat before the batteries & blue ice did.  
 

73 - John - N7GHZ

On Thu, Aug 13, 2020, 12:28 PM Hasan Schiers N0AN <hbasri.schiers6@...> wrote:
Dan,
No. FT8 is virtually 100% duty cycle. It has little to do with transmitted bandwidth.
73, N0AN
Hasan



On Thu, Aug 13, 2020 at 2:14 PM d_ziolkowski <dan.ziolkowski@...> wrote:
Hello all=

We have all been educated that due to the high duty cycle of FT8, it is wise to not run full power of you rig to avoid burning up the finals. 

My question relates to the effect of the transmitted bandwidth, which in FT8 is 50HZ, has on the actual power loading of the finals. 

Since when transmitting a 50Hz signal via a transmitter capable of about 2Khz or so, would this , in effect , very lightly load the finals, even at full power?

Thanks

Dan KC2STA






Alan G4ZFQ
 

But--- a CW signal is 100% carrier.
FT8 is USB , little to no carrier.
Think AM vs SSB.
Dan,

Well, no.

CW may be produced with a SSB radio. It is an on/off single tone, not actually 100% duty cycle because it is keyed. No "carrier".
Digital modes are usually a series of 100% duty cycle single tones, yes produced in SSB mode, no carrier.

AM does not come into it. AM has a carrier which is modulated so modulated AM actually has 3 "tones".

73 Alan G4ZFQ


Frank Donovan
 

Hi Dan,

FT8 is 100% duty cycle during the entire duration of its 12.6 second transmission.

FT8 is not USB.   Your transceiver is set to USB only so it can translate
the FT8 signal generated by your sound card to selected ham bands.
Think of your transceiver as a mixer with a filter on the output so you
don't get two sidebands from the mixer.

73
Frank
W3LPL


From: "d_ziolkowski" <dan.ziolkowski@...>
To: main@wsjtx.groups.io
Sent: Thursday, August 13, 2020 8:58:10 PM
Subject: Re: [WSJTX] Duty cycle question

But--- a CW signal is 100% carrier. 

FT8 is USB , little to no carrier.

Think AM vs SSB.

Dan KC2STA



On Thu, Aug 13, 2020 at 4:29 PM Joe WB9SBD <nss@...> wrote:
How narrow is a dead carrier? a LOT smaller than 50 hz, so how long can your rig like a CW Key be pressed down and held?

Joe WB9SBD

The Original Rolling Ball Clock
Idle Tyme
Idle-Tyme.com
http://www.idle-tyme.com

On 8/13/2020 2:14 PM, d_ziolkowski wrote:
Hello all=

We have all been educated that due to the high duty cycle of FT8, it is wise to not run full power of you rig to avoid burning up the finals. 

My question relates to the effect of the transmitted bandwidth, which in FT8 is 50HZ, has on the actual power loading of the finals. 

Since when transmitting a 50Hz signal via a transmitter capable of about 2Khz or so, would this , in effect , very lightly load the finals, even at full power?

Thanks

Dan KC2STA


    




--
Dan Ziolkowski KC2STA
SKCC #4290T
Ubuntu LINUX




careyfisher@...
 

You can't talk about Duty Cycle without talking about component temperature. You can run something at 100% duty cycle forever if you can keep the temperature within the ratings of the components.
So, Joe WB9SBD, you can certainly do a 60 minutes On, 60 minutes Off duty cycle if you can keep the components cool.


73, Carey, WB4HXE

On Thu, Aug 13, 2020 at 5:16 PM Frank Donovan <donovanf@...> wrote:
Hi Dan,

FT8 is 100% duty cycle during the entire duration of its 12.6 second transmission.

FT8 is not USB.   Your transceiver is set to USB only so it can translate
the FT8 signal generated by your sound card to selected ham bands.
Think of your transceiver as a mixer with a filter on the output so you
don't get two sidebands from the mixer.

73
Frank
W3LPL


From: "d_ziolkowski" <dan.ziolkowski@...>
To: main@wsjtx.groups.io
Sent: Thursday, August 13, 2020 8:58:10 PM
Subject: Re: [WSJTX] Duty cycle question

But--- a CW signal is 100% carrier. 

FT8 is USB , little to no carrier.

Think AM vs SSB.

Dan KC2STA



On Thu, Aug 13, 2020 at 4:29 PM Joe WB9SBD <nss@...> wrote:
How narrow is a dead carrier? a LOT smaller than 50 hz, so how long can your rig like a CW Key be pressed down and held?

Joe WB9SBD

The Original Rolling Ball Clock
Idle Tyme
Idle-Tyme.com
http://www.idle-tyme.com

On 8/13/2020 2:14 PM, d_ziolkowski wrote:
Hello all=

We have all been educated that due to the high duty cycle of FT8, it is wise to not run full power of you rig to avoid burning up the finals. 

My question relates to the effect of the transmitted bandwidth, which in FT8 is 50HZ, has on the actual power loading of the finals. 

Since when transmitting a 50Hz signal via a transmitter capable of about 2Khz or so, would this , in effect , very lightly load the finals, even at full power?

Thanks

Dan KC2STA


    




--
Dan Ziolkowski KC2STA
SKCC #4290T
Ubuntu LINUX






--
Carey Fisher


--
73, Carey, WB4HXE


JP Tucson, AZ
 

Actually, think "envelope"!

100 Watts is, in general, 100 Watts!

If you have a VOICE SSB signal over 2 kHz, that 100 Watts is spread across that 2 kHz envelope. That is why a 100 Watt CW signal will punch through the noise better as its envelope is much narrower. That is also why a typical CW filter is only 400 Hz wide.

FT8 transmitted signals are only 50 or so Hz wide & No carrier, so they punch through even better, but because of remarkable DSP & algorithms, their receive levels are better too - down below the noise floor.

As a comparison, a broadcast TV signal could be 1 million Watts, but that's spread over 6 MHz. Pretty inefficient really!  
  

73 - John - N7GHZ





On Thu, Aug 13, 2020, 1:58 PM d_ziolkowski <dan.ziolkowski@...> wrote:
But--- a CW signal is 100% carrier. 

FT8 is USB , little to no carrier.

Think AM vs SSB.

Dan KC2STA



On Thu, Aug 13, 2020 at 4:29 PM Joe WB9SBD <nss@...> wrote:
How narrow is a dead carrier? a LOT smaller than 50 hz, so how long can your rig like a CW Key be pressed down and held?

Joe WB9SBD

The Original Rolling Ball Clock
Idle Tyme
Idle-Tyme.com
http://www.idle-tyme.com

On 8/13/2020 2:14 PM, d_ziolkowski wrote:
Hello all=

We have all been educated that due to the high duty cycle of FT8, it is wise to not run full power of you rig to avoid burning up the finals. 

My question relates to the effect of the transmitted bandwidth, which in FT8 is 50HZ, has on the actual power loading of the finals. 

Since when transmitting a 50Hz signal via a transmitter capable of about 2Khz or so, would this , in effect , very lightly load the finals, even at full power?

Thanks

Dan KC2STA


    




--
Dan Ziolkowski KC2STA
SKCC #4290T
Ubuntu LINUX


Arthur Bernstein
 

Much of this has to do with the ratings of the gear you are using. In the old days using a transmitter with sweep tubes would get a lot of burnouts, fast.
Duty cycle is determined by mode, time and ambient temperature. CW is 100% duty cycle when the key is depressed. Periods of non transmission between key down reduces the cycle. Typocally CW is 50% duty cycle which will decrease with the higher speed of CW. SSB is of a lower duty cycle due to average PEP variations during a transmission. FT8 transmissions are reported to be on average 12 seconds. Even at full power that’s well within ratings. For example my Elecraft K3 is rated CW and SSB 100% for 10 minutes. 100 watts key down at 25 C ambient.My KPA500 is rated 500 watts 10 minutes key down, 5 minutes standby., all modes CW/SSB/DATA. Of course this is with built in cooling fans. Would think this is more typical than not FT8 is less severe a duty cycle than FSK.
Art., N2KA..


d_ziolkowski
 

Fellows:

Maybe forget about the duty cycle.

What I'm really asking is how much power is dissipated ie temp rise of finals if I was to run a 50 HZ tone USB. vs a 500 hz tone? Absolute Power level does not matter.

Thanks 

Dan KC2STA


On Thu, Aug 13, 2020 at 5:31 PM <careyfisher@...> wrote:
You can't talk about Duty Cycle without talking about component temperature. You can run something at 100% duty cycle forever if you can keep the temperature within the ratings of the components.
So, Joe WB9SBD, you can certainly do a 60 minutes On, 60 minutes Off duty cycle if you can keep the components cool.


73, Carey, WB4HXE

On Thu, Aug 13, 2020 at 5:16 PM Frank Donovan <donovanf@...> wrote:
Hi Dan,

FT8 is 100% duty cycle during the entire duration of its 12.6 second transmission.

FT8 is not USB.   Your transceiver is set to USB only so it can translate
the FT8 signal generated by your sound card to selected ham bands.
Think of your transceiver as a mixer with a filter on the output so you
don't get two sidebands from the mixer.

73
Frank
W3LPL


From: "d_ziolkowski" <dan.ziolkowski@...>
To: main@wsjtx.groups.io
Sent: Thursday, August 13, 2020 8:58:10 PM
Subject: Re: [WSJTX] Duty cycle question

But--- a CW signal is 100% carrier. 

FT8 is USB , little to no carrier.

Think AM vs SSB.

Dan KC2STA



On Thu, Aug 13, 2020 at 4:29 PM Joe WB9SBD <nss@...> wrote:
How narrow is a dead carrier? a LOT smaller than 50 hz, so how long can your rig like a CW Key be pressed down and held?

Joe WB9SBD

The Original Rolling Ball Clock
Idle Tyme
Idle-Tyme.com
http://www.idle-tyme.com

On 8/13/2020 2:14 PM, d_ziolkowski wrote:
Hello all=

We have all been educated that due to the high duty cycle of FT8, it is wise to not run full power of you rig to avoid burning up the finals. 

My question relates to the effect of the transmitted bandwidth, which in FT8 is 50HZ, has on the actual power loading of the finals. 

Since when transmitting a 50Hz signal via a transmitter capable of about 2Khz or so, would this , in effect , very lightly load the finals, even at full power?

Thanks

Dan KC2STA


    




--
Dan Ziolkowski KC2STA
SKCC #4290T
Ubuntu LINUX






--
Carey Fisher


--
73, Carey, WB4HXE


--
Dan Ziolkowski KC2STA
SKCC #4290T
Ubuntu LINUX


Joe WB9SBD
 

But the tone MCW a single tone of 1KHz on a signal dial freq of 14.200 to anyone listening hears a solid carrier tone of 1 Khz in frequency.
It is exactly the same power use.

Joe WB9SBD

On 8/13/2020 3:58 PM, d_ziolkowski wrote:

But--- a CW signal is 100% carrier. 

FT8 is USB , little to no carrier.

Think AM vs SSB.

Dan KC2STA



On Thu, Aug 13, 2020 at 4:29 PM Joe WB9SBD <nss@...> wrote:
How narrow is a dead carrier? a LOT smaller than 50 hz, so how long can your rig like a CW Key be pressed down and held?

Joe WB9SBD

The Original Rolling Ball Clock
Idle Tyme
Idle-Tyme.com
http://www.idle-tyme.com

On 8/13/2020 2:14 PM, d_ziolkowski wrote:
Hello all=

We have all been educated that due to the high duty cycle of FT8, it is wise to not run full power of you rig to avoid burning up the finals. 

My question relates to the effect of the transmitted bandwidth, which in FT8 is 50HZ, has on the actual power loading of the finals. 

Since when transmitting a 50Hz signal via a transmitter capable of about 2Khz or so, would this , in effect , very lightly load the finals, even at full power?

Thanks

Dan KC2STA





--
Dan Ziolkowski KC2STA
SKCC #4290T
Ubuntu LINUX


    


Frank Donovan
 

Hi Dan,

You can very easily answer your question yourself.

Go into your CONFIG menu and select PA TEMP

Then run your CW vs. FT8 experiment

The results will be identical

73
Frank
W3LPL



From: "d_ziolkowski" <dan.ziolkowski@...>
To: main@wsjtx.groups.io
Sent: Thursday, August 13, 2020 10:00:27 PM
Subject: Re: [WSJTX] Duty cycle question

Fellows:

Maybe forget about the duty cycle.

What I'm really asking is how much power is dissipated ie temp rise of finals if I was to run a 50 HZ tone USB. vs a 500 hz tone? Absolute Power level does not matter.

Thanks 

Dan KC2STA


On Thu, Aug 13, 2020 at 5:31 PM <careyfisher@...> wrote:
You can't talk about Duty Cycle without talking about component temperature. You can run something at 100% duty cycle forever if you can keep the temperature within the ratings of the components.
So, Joe WB9SBD, you can certainly do a 60 minutes On, 60 minutes Off duty cycle if you can keep the components cool.


73, Carey, WB4HXE

On Thu, Aug 13, 2020 at 5:16 PM Frank Donovan <donovanf@...> wrote:
Hi Dan,

FT8 is 100% duty cycle during the entire duration of its 12.6 second transmission.

FT8 is not USB.   Your transceiver is set to USB only so it can translate
the FT8 signal generated by your sound card to selected ham bands.
Think of your transceiver as a mixer with a filter on the output so you
don't get two sidebands from the mixer.

73
Frank
W3LPL


From: "d_ziolkowski" <dan.ziolkowski@...>
To: main@wsjtx.groups.io
Sent: Thursday, August 13, 2020 8:58:10 PM
Subject: Re: [WSJTX] Duty cycle question

But--- a CW signal is 100% carrier. 

FT8 is USB , little to no carrier.

Think AM vs SSB.

Dan KC2STA



On Thu, Aug 13, 2020 at 4:29 PM Joe WB9SBD <nss@...> wrote:
How narrow is a dead carrier? a LOT smaller than 50 hz, so how long can your rig like a CW Key be pressed down and held?

Joe WB9SBD

The Original Rolling Ball Clock
Idle Tyme
Idle-Tyme.com
http://www.idle-tyme.com

On 8/13/2020 2:14 PM, d_ziolkowski wrote:
Hello all=

We have all been educated that due to the high duty cycle of FT8, it is wise to not run full power of you rig to avoid burning up the finals. 

My question relates to the effect of the transmitted bandwidth, which in FT8 is 50HZ, has on the actual power loading of the finals. 

Since when transmitting a 50Hz signal via a transmitter capable of about 2Khz or so, would this , in effect , very lightly load the finals, even at full power?

Thanks

Dan KC2STA


    




--
Dan Ziolkowski KC2STA
SKCC #4290T
Ubuntu LINUX






--
Carey Fisher


--
73, Carey, WB4HXE


--
Dan Ziolkowski KC2STA
SKCC #4290T
Ubuntu LINUX