Re: voltage reading for DSB 20 meter version


Carl Weiberg
 

Hi all,
I just completed my 20m build and after countless CQ’ and checking PSKreporter I don’t believe the output of the transmitter to be anywhere near a watt. I checked for signal on my main HF receiver, and there is a signal. PSKreporter confirmed my HF rig reception as well. However it was very weak. I am running a EFHF with perfect SWR as well. I also have a 40m unit, and tested that last night and PSKreported shows receptions across out west in the evening, so the 40 has some output.

I do not have a qrp meter. Is there any way to determine true output on these units? The receivers work ok, not outstanding but enough to get reasonable reception. I am quite pleased. 

I run other QRP rigs, but nothing sub 1 watt.

Thanks!
Carl

iPhone Aloha

On Feb 20, 2021, at 5:48 PM, tem494@... wrote:


Thank you and yes it should have been the D4D.
I Will work on it tomorrow when I am a little fresher and maybe a little better attitude.
tom

On Sat, Feb 20, 2021 at 5:13 PM Jim Allyn - N7JA <jim@...> wrote:
By DSB I am guessing you mean the D4D  -  double sideband for digital mode?  Since you have both the 20 meter version and the 40 meter version, you could start by measuring voltages in the functioning 40 meter radio and compare the voltage readings in the non-functioning 20 meter version.  As far as I know they are identical except for the component values in the low pass filter at the output and a few other frequency determining components.  Beyond that, you're probably looking for something in the Q3/Q4 circuitry, so I would start comparing voltages there.  Off the top of my head, I'll say you should have about .7 volts between base and emitter on both Q3 and Q4, and you should have 12 volts at the collector of Q4.


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CW

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