The spec for both modules briefly mentions a 1% maximum transmit duty cycle at max power (13 dBm or 20 dBm). There's no information about the time period over which this is appropriate (1 ms out of 100 msec is probably good, but how about 1 sec out of 100 sec?), nor any information about scaling up the duty cycle as transmit power is reduced.
Has anybody seen a problem with this?
Have you even measured a temp increase from transmitting? (of course the weak link of the TX chain may be in a different part of the module from the temperature sensor).
Or is it just a CYA "spec"?
If I understood your first question right, the subject probably pertains to the regulation of short range devices, see here (https://en.wikipedia.org/wiki/Short_Range_Devices) and especially this PDF (http://www.erodocdb.dk/docs/doc98/official/pdf/rec7003e.pdf). I gathered that a lot of these devices accessible for consumer use interpret this rather loosely...
The data sheet is full of non-details. A lot is left to your imagination. :(
I'm not sure, but that may have contributed to me frying two 69HWs. I built a patch antenna that is very sensitive to near by objects. After carefully tuning it I installed it in a plastic case that moved the resonant freq. SWR went to 20:1. After a couple tx's they died. I was running full pwr by accident. I've re-aligned the installed antenna and have my fingers crossed.
If I was 100% sure that's what killed it I would recommend staying below 1/2 pwr (-3db).
A future project will require 'continuous' mode. I'll know more after running 100% duty.
Just to sum up. The HopeRF data sheets very tersely specify a max duty cycle at full power of 1% (for both chips), but give no derating for lesser power.
Kobuki suggests that this may be a matter trying to meet regulatory requirements rather than a physical chip limitation. From looking at the linked documents, regulations on duty cycle may be very complex and vary by jurisdictions (10%, 1% 0.1% and 0.01% are mentioned in various contexts). Maybe HopeRF chose to include 1% as a reasonable compromise.
John k2ox has experience frying two 69HW's which could be related, but it may have been just due to antenna mismatch rather than exceeding the power output duty cycle; he'll know more when the has tested 100% duty cycle for a while.
John - are you checking the on-chip temperature sensor as you test? (Yes, the temp sensor may be in a different part of the chip than the power amp, but keeping track of it would still give some info)