Duty Cycle?

[Lazy-Ferret]

I have a question regarding Duty Cycle..

Now I know with Welders, and Compressors, the Duty cycle relates to a 10min period, so, if it has a 30% duty cycle, it can be used for 3 mins, and then must rest for 7mins, but that is not the case for everything that has a duty cycle.

I believe in some duty cycles it is equals, so if it has a 5min duty cycle, it can be on for no more than 5 mins and then must be off for a minimum of 5 mins, but if you use it for just 3, you only meed to rest it for 3, so it basically is the longest time you can use it for.

If you had a walkie talkie with the following, what would you think the practical usage times would be?

Duty Cycle, 03/03/54 min (Rx/Tx/Standby)

I can understand 3 min on, 3 min off for transmit, but what about receive? As for standby, or is it saying that the maximum time you can have the radio turned on is 54mins, and then it must be switched off for 54mins? or have I got this completely wrong (I hope)...

Please explain

[Fez_uk]

receive is when audio is coming out of the radio.

Standby is when the radio is on but not receiving any transmissions.

You don't need to wait 3 mins before you transmit again. These cycles are just a way for that to explain how long the battery would last. Not the same as duty cycle for welders etc

[Lazy-Ferret]

Originally Posted by Fez_uk

receive is when audio is coming out of the radio.

Standby is when the radio is on but not receiving any transmissions.

You don't need to wait 3 mins before you transmit again. These cycles are just a way for that to explain how long the battery would last. Not the same as duty cycle for welders etc

Cheers, I got that bit, but I can not work out what info the duty cycle is supposed to be giving me..

Basically, the figures are, 1.8Ah battery. 1.4A on transmit, 380mA on receive, and just 75mA on standby. So I have done the Calcs, and basically, 24 hours on standby, and 1 1/4 hours on transmit, ans 2 1/2 hours receiving.

[solarman216]

not sure what your numbers refer to but as with all transmitting equipment you cannot transmit continuously without the risk of heat damage to the output transistors, much more so if the SWR is bad as it loads them fare higher than if the SWR is good, I guess briggie would be better able to answer this one, Rick

[The Patrolman]

Originally Posted by Lazy-Ferret

Cheers, I got that bit, but I can not work out what info the duty cycle is supposed to be giving me..

Basically, the figures are, 1.8Ah battery. 1.4A on transmit, 380mA on receive, and just 75mA on standby. So I have done the Calcs, and basically, 24 hours on standby, and 1 1/4 hours on transmit, ans 2 1/2 hours receiving.

So you have 1800mAh available from one battery;

if it does not pick up any signal at all it can listen for 24 Hrs - 1800mAh/75mA=24hrs.( duty cycle for Standby = 24hrs/24hrs x100%= 100% duty cycle)
if you turned it off for as long as it is on 1hr off and one hour on then in a 24hr period it would be on 12hrs .( duty cycle for Standby = 12hrs/24hrs x100%= 50% duty cycle) in this case you have determined the duty cycle of 50% and the battery will last for 48hrs

If you were tuned in to a radio station and were picking up music constantly that would kill the battery in 1800mAh/380mA= 4.7 Hrs - depending on the volume
If you are out greenlaning and only receive local traffic that is picked up for 12 minutes of every hour, this may be 6 lots of 2 mins or 3 lots of 4mins etc( duty cycle for Rx = 12mins/60mins x100%= 20% duty cycle) so with a 20%DC your battery will last 23 hrs, obviously this needs to be off set withthe 75mA constant standby usage
Etc Etc Getting bored typing now

Duty cycleFrom Wikipedia, the free encyclopedia
The duty cycle is defined as the ratio between the pulse duration () and the period () of a rectangular waveform. A duty cycle is the percentage of one period in which a signal is active.[1][2][3] A period is the time it takes for a signal to complete an on-and-off cycle.
Thus, a 60% duty cycle means the signal is on 60% of the time but off 40% of the time. The "on time" for a 60% duty cycle could be a fraction of a second, a day, or even a week, depending on the length of the period.

Duty cycles can be used to describe the percent time of an active signal in an electrical device such as the power switch in a switching power supply

[The Patrolman]

And what Rick said to