Power Output measurement #ubitxcw

ajparent1/KB1GMX <kb1gmx@...>


Dead on.  DC votlage to the radio has a very large impact on power out.
All the work done back last May I included that as many has the Wbrand
audio chip that would fry at 13V and they would know what not regulating
the voltage to the chip limits them too.

I do all testing at either 12.6 (charged gellcell) or 13.8 (automotive systems and
most bench power for high power radios. Astron and Samlex).

Since the power amp design is marginal over all  DC  power applied has far to
great an effect.  So yes the numbers can vary widely and if the DC is not speced
as well as what band its going to be mostly guess.  Also if you have five units
and the same power it all over the map.


Richard Pushman

I should redo this, get a few more data points, be more thorough.

Tom, wb6b

That is an interesting chart.

Seems like 12 volts is marginal for these rigs; with surprising large power output variation for small changes in supply voltage. In past threads people have reported widely varying output power, rarely did they report the voltage they were running the rig on. I wonder what supply voltage was used for the original specified power output listed on the HF Signals site was. 

Here is a less scientific but similar thread on supply voltage vs power out:

Tom, wb6b

Richard Pushman

Attached is a chart recording output power versus frequency at two different input voltages, 12.0 volts, and 14.0 volts.
I didn't measure current draw.

Output went thru a 30 dB attenuator into a Boonton RF Power Meter.  (e.g., a measurement or 10 dBm was recorded, then 30 added to it to account for the attenuator, then converted to watts - excel cell formula being "=(10^(G3/10))/1000". )

The switching points of the output filters are clearly visible.