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Bitx20 I have completed the RF section and now doing the current test on transmit and recieve. #bitx20help

shytron
 

?I have completed the RF section and now doing the current test on transmit and receive. I get the 12 ma on receive but only 16 on transmit. Supposed to be 30. Is it because this jumper needs to be in for the test?
At the pads for the jumper that is to be installed later solder short wires to be used to clip on to with a
current meter. This test point will be used to set the bias current for the final output transistor,? You guys are inspiring. Thanks. James kc3cik



IRF510.
At the pads for "
?
?
IRF510.
 

Is this a bitx20 version 3 with the separate PA board?
Leonard
shytron
 

Yes, should have noted that. The latest board from Ashar
 

That confused the issue again. Is it a 2 board set?

Is this the pa board you are working on?

Leonard
shytron
 

Yes it is the version 3b. Two boards pa and exciter. This is the first test with the two boards connected with the RF section completed on the exciter board..The jumper on the pa board to be installed later is the test point to set the bias current, IRF510.? Could this be why the current on the RF section is 16 instead of 30 because this jumper is not installed? Thank you for your patience and help. Reading the daily post from everybody has given me the inspiration to complete this project and pass the general exam. James, KC3CIK
shytron
 

Please excuse me for this correction. It is not the current on the RF section. It is the current from the pa board to the exciter board on transmit test. The current test is correct in receive. Again thanks.
shytron
 

Yes the new BITX 3B. I did find a resistor with the wrong value. Replaced the 47 with the correct value 470 on the exciter board. Now the current is the same on the transmit and receive. 12 millamps. It is supposed to be 30 ma on transmit. The receive voltages on Q1 are correct and the transmit voltage on Q13 are also correct.. It has to be something very simple right in front of me but I cant see it. Its fun though.
 

Most of us in the forum have the rigs from hfsignals.com
Do you have one of these from Sunil?
? ??
Most of us have no idea what transmit current into the exciter should be on Sunil's board set.
I suspect Ashhar does not either.

Anyway, my guess would be that current increase when going to transmit on that exciter would mostly be around Q14.
I suggest you measure DC voltages at Q14's emitter, base and collector for transmit and receive.
Should be around zero for receive, well above ground for transmit.

Also, if you want to keep an intelligent conversation going on this, don't change the subject heading.
Took me a few minutes to find your old thread where the problem was described.

Jerry

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Arv Evans
9:08 am???

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Shytron

In order to provide help we would need to know a bit more about your problem.
  • Which model BITX do you have?

  • What test equipment do you have available?

  • What are the symptoms of the problem?

  • How far have you already gone with testing?
The group is usually quite helpful but "something is broken" is just too little?
information to work with.

Arv? K7HKL
_._

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On Wed, Mar 28, 2018 at 9:08 AM, shytron via Groups.Io?<shytron@...>?wrote:

I have a BITX20 with some problems with the current measurements and cant seem to get any help with this group. I would have to say i am very discouraged. Ill just contact Ashar.
 

What is the link to the assembly instructions you are using?

Leonard

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