Topics

Transmit Problem

Larry Plummer
 

I assembled my uBITX as a WSPR transmitter.  I use a SignaLink USB for receive and transmit audio plus PTT.  Everything works as it should on 30 meters and lower.  On 20 meters and higher when, when PTT is activated, the LCD shows "Band Select" as if the push button has been pushed.  This is with no audio meaning no RF output.  I tried adding a bypass cap to the pushbutton which didn't change anything.  The only way to get it out of TX mode is to turn off the power.

Larry
W6LVP

ajparent1/KB1GMX
 


Somethign about your assembly is getting RF into the wires going to the Raduino.

Hint Keep all wires far away from the heatsinks, lots of RF there.  

This has been seen many times before usually on 40 or 20M.

Allison

M Garza <mgarza896@...>
 

Put a clip on ferrite on the wire assembly going to the Raduino from the encoder.  This should resolve the issue.  I had something similar and this fixed it for me.

73s

Marco - KG5PRT 

On Sun, Sep 16, 2018, 1:44 PM ajparent1/KB1GMX <kb1gmx@...> wrote:

Somethign about your assembly is getting RF into the wires going to the Raduino.

Hint Keep all wires far away from the heatsinks, lots of RF there.  

This has been seen many times before usually on 40 or 20M.

Allison

Larry Plummer
 

Thanks for the suggestions.  There is no RF being generated since there is no modulation audio.  Second, I tried ferrites on the wire bundles and didn't help.

Larry

M Garza <mgarza896@...>
 

Since this is happening on specific bands and not all the bands, it sounds like rf.  Does it happen into a dummy load or only on an antenna?  Do you have enough power supply?

Just questions to try to troubleshoot.

Marco - KG5PRT 

On Sun, Sep 16, 2018, 3:06 PM Larry Plummer <lplummer@...> wrote:

Thanks for the suggestions.  There is no RF being generated since there is no modulation audio.  Second, I tried ferrites on the wire bundles and didn't help.

Larry

ajparent1/KB1GMX
 

also if you add caps across wire do it at the board not the far end of the wires!

Larry Plummer
 

Thanks for the suggestions.  I put ferrites on all of the cables which do not run near the PA section.  Did not help.  I lined the inside of my plastic enclosure with aluminum foil which is grounded and that did solve the problem.

iz oos
 

Just a question about using EMI ferrites. Can they be used in the large connectors (Raduno and audio) or would they make more troubles, eg. lowering the output of the oscillators or whatelse?


Il 17/set/2018 06:55, "Larry Plummer" <lplummer@...> ha scritto:
Thanks for the suggestions.  I put ferrites on all of the cables which do not run near the PA section.  Did not help.  I lined the inside of my plastic enclosure with aluminum foil which is grounded and that did solve the problem.

Mike Short
 

It is no accident that commercial radios are in metal cases. While many of the plastic cases look great, they are not for RF devices.


--
Mike
AI4NS

Yves vk2auj
 

I had the same problem when transmitting with the mike (not CW)  which I couldn't resolve with the solutions proposed in the posts I could find.

I resolved the issue by installing a capacitor between the red wire (PTT) and the yellow wire (ground) on the Arduino plug.  Unsure of the value however the red square caps read:
WIMA
0.1
100-
RD or RQ (not clear)

Yves vk2auj/ve2auj

William R Maxwell
 

0.1 = 100uF, 100 probably = 100V

Bill VK7MX

Evan Hand
 

I am pretty sure the .1 is .1uf =100nf. I agree with the 100 volt

Wayne Leake
 

 Regarding the shielded enclosures, yup, most good radios are enclosed in metal cases.
 Receiver only is far less fussy.
 I was looking at a number of possible cases for my BITX, and decided on a BUD enclosure, all aluminum
 It is big enough for the HF Signal BITX40, but turns out not for another BITX I am assembling.
 Boards too wide to fit both exciter and PA boards in it.
 I see all these great looking plastic cases, but figured that I do not want to go with no shielding.
 Hence the one that will go into a cassette  deck case will have shielding.
 The ferrite beads have their places, but don't take the place of good shielding, which may also help prevent images and harmonics , plus spurs, from escaping.
 YMMV
 Wayne WA2YNE

Brian L. Davis
 

I used this to line the interior of my plastic case.  I overlapped the tape and soldered sections together at the overlap.

https://www.amazon.com/dp/B01I1XNY1E/ref=sspa_dk_detail_0?psc=1&pd_rd_i=B01I1XNY1E

William R Maxwell
 

Ooops, hit the wrong key. Yes, 100 nF.

Lawrence Galea
 

Have you tried putting the amplifier on the back panel?


On Fri, Nov 9, 2018 at 5:59 AM Wayne Leake <wayneleake@...> wrote:
 Regarding the shielded enclosures, yup, most good radios are enclosed in metal cases.
 Receiver only is far less fussy.
 I was looking at a number of possible cases for my BITX, and decided on a BUD enclosure, all aluminum
 It is big enough for the HF Signal BITX40, but turns out not for another BITX I am assembling.
 Boards too wide to fit both exciter and PA boards in it.
 I see all these great looking plastic cases, but figured that I do not want to go with no shielding.
 Hence the one that will go into a cassette  deck case will have shielding.
 The ferrite beads have their places, but don't take the place of good shielding, which may also help prevent images and harmonics , plus spurs, from escaping.
 YMMV
 Wayne WA2YNE

Bill Cromwell <wrcromwell@...>
 

Hi Wayne,

Shielding can be added to the interior of those "attractive plastic boxes". I made my own steel box from new steel. But I have used the aluminum foil lining inside wood or plastic boxes, The heavier foil pans that are sold for baking or the ones frozen meals come in are much sturdier than the paper thin foil sold for wrapping food.

73,

Bill KU8H

On 11/9/18 5:20 PM, Lawrence Galea wrote:
Have you tried putting the amplifier on the back panel?
On Fri, Nov 9, 2018 at 5:59 AM Wayne Leake <wayneleake@... <mailto:wayneleake@...>> wrote:
 Regarding the shielded enclosures, yup, most good radios are
enclosed in metal cases.
 Receiver only is far less fussy.
 I was looking at a number of possible cases for my BITX, and
decided on a BUD enclosure, all aluminum
 It is big enough for the HF Signal BITX40, but turns out not for
another BITX I am assembling.
 Boards too wide to fit both exciter and PA boards in it.
 I see all these great looking plastic cases, but figured that I do
not want to go with no shielding.
 Hence the one that will go into a cassette  deck case will have
shielding.
 The ferrite beads have their places, but don't take the place of
good shielding, which may also help prevent images and harmonics ,
plus spurs, from escaping.
 YMMV
 Wayne WA2YNE
--
bark less - wag more