Antenna Tuner isue


David Wilcox
 

 
I have built the 4SQRP Group antenna tuner and really think it is a fantastic kit and easy to build with the provided instructions. It seems to work quite well and I have tested it against other antenna tuners that I have and it is spot on in tuning a long wire that I have is a temporary antenna.
 
I have noticed though, that when I rapidly turn the left sided tuning capacitor it is scratchy in the audio that I am hearing on the receiver. I didn't think that was possible with these small tuning caps since they have a plastic layer between each of the veins.
 
Since it does work correctly is this a problem? Should I replace the cap?
 
Thank you for any and all advice.
 
Dave K8WPE


Curt
 

Dave

nice on your successful build.  Scratchy audio heard when exercising the tuner -- wow very cool to translate mechanical motion into audio modulated electrons -- this is called microphonics, I think ...

No I don't think this is what you are experiencing.  you did not mention that you are transmitting when you here these sounds - but I suspect this is the case.  If so, it is a little instability in the PA or driver stage under varying load to the antenna (often high VSWR but not always).  this is more noticeable in a transceiver that feed transmit audio into the receive chain for the side-tone.  it is an oddity that it occurs while tuning -- hopefully it sounds much clearer when tuner is appropriately adjusted for a match? 

If you are not hearing it after the tuner is adjusted in normal operation, I suggest all is well enough. 

73 CUL

Curt


sigcom1
 

Possible static electricity generated by rapid rotation of capacitor rotor?  Wouldn't take much to generated enough to hear in a receiver.  However, I would think that the inductor would bypass that to ground.

One way to confirm; swap the Polyvaricons.  If the problem is the same, it's likely static.  If if follows the cap., it's defecdtive.

73.......Steve Smith WB6TNL


Johnny AC0BQ
 

Ge Dave
If it were mine,
I would replace the cap.
Be careful not to over heat the tabs when installing!
72
Johnny AC0BQ


On Thursday, October 27, 2016, sigcom@... [4sqrp] <4sqrp@...> wrote:
 

Possible static electricity generated by rapid rotation of capacitor rotor?  Wouldn't take much to generated enough to hear in a receiver.  However, I would think that the inductor would bypass that to ground.


One way to confirm; swap the Polyvaricons.  If the problem is the same, it's likely static.  If if follows the cap., it's defecdtive.

73.......Steve Smith WB6TNL



--
QRP....."More smiles per Watt"
72
JOHNNY AC0BQ  ..




Curt
 

I dunno -- it may be just fine as is ....

We traded e-mail .. he clarified the noise is heard on receive.  I suggested it could be artifact of AGC action of the receiver, or merely hearing the change in the noise as tuner is adjusted. 

Another way of looking at this -- if the 'sound' is okay whether tuner is perfectly adjusted, or misadjusted -- then the tuner is okay. 

Glad to hear folk building and operating stuff -- and to be part of the community. 

Curt