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Output Power is less than 3W

unnikrish7997@...
 

hello dear people,

My output power of my BitX 40 is less than 3W while checking an SWR meter. I preset to control volume is set to its maximum. One of my friend have the same problem.

Waiting for the answers.

regards 

Unni Krishnan 

unnikrish7997@...
 

Please read preset to control voltage. 

Steve Greer
 

Let's start with the basics.  Power supply voltage and amperage.  Type of antenna?  Have you tried into a 50 ohm dummy load?  All hams should have one.  Check into a dummy load and report back.

On Wed, May 3, 2017 at 11:33 AM, <unnikrish7997@...> wrote:

hello dear people,

My output power of my BitX 40 is less than 3W while checking an SWR meter. I preset to control volume is set to its maximum. One of my friend have the same problem.

Waiting for the answers.

regards 

Unni Krishnan 


Soundararajan Ra.
 

Same problem with me also RFvoltage at base of pre  driver transistor 200 mv in defective board where us working one 500 mv .



On May 3, 2017 9:06 PM, "Steve Greer" <km4ous@...> wrote:
Let's start with the basics.  Power supply voltage and amperage.  Type of antenna?  Have you tried into a 50 ohm dummy load?  All hams should have one.  Check into a dummy load and report back.

On Wed, May 3, 2017 at 11:33 AM, <unnikrish7997@...> wrote:

hello dear people,

My output power of my BitX 40 is less than 3W while checking an SWR meter. I preset to control volume is set to its maximum. One of my friend have the same problem.

Waiting for the answers.

regards 

Unni Krishnan 



unnikrish7997@...
 

tried with  a dummy load. thus got the output power

John T P
 

Dear Unni,

Please check IRF510 is drawing more than 1A current, when you speak to the mic.
You said already the drive is at Max.
Also when you don't speak around 180mA.
You can adjust gate bias pot to get 180mA.

Perhaps you can reach upto 5W output maximum.

73ees

JOHN T.P.
Tharayil House
Sree Ayyappa Road
Kuriachira
Thrissur-680 006 
Mobile: +91-960-5000-445 / 88-07-007-933

On Wed, May 3, 2017 at 9:03 PM, <unnikrish7997@...> wrote:

hello dear people,

My output power of my BitX 40 is less than 3W while checking an SWR meter. I preset to control volume is set to its maximum. One of my friend have the same problem.

Waiting for the answers.

regards 

Unni Krishnan 


Steve Greer
 

what are you using to supply power what is the current draw when transmitting. Have you looked on the wire-up section of hfsigs.com to make sure everything is biased correctly.  Let's save a hundred questions and please tell us what steps you as the builder have taken to identify or troubleshoot the problem.

On Wed, May 3, 2017 at 11:43 AM, <unnikrish7997@...> wrote:
tried with  a dummy load. thus got the output power


John Backo
 

All these are good things to check, but don't forget the driver transistor
and its circuit. Especially the conformation and the solder joints on its output
transformer. Maybe the 2N2219A needs work.

That being said, it is also possible that this is normal behavior for the IRF510.
They are notorious for their extremely variability, and maybe these particular units are capable of
only 3W output or so. I think the way to check that would be changing the
drain voltage (after checking and verifying everything else) and seeing what
happens...

john
AD5YE

Nick
 

Keep in mind the standard swr/power meter is not peak reading. Depending on the various audio frequencies coming in, the meter is going to show more of an average reading. It will show low. For more better measurements you need a peak reading meter for SSB or an oscilloscope to catch the peak voltages and calculate power. Another way to do it is if you can apply a single audio tone to the mic. Maybe from a frequency generator phone app? That should get you closer to peak on a standard meter so long as the input frequency is within the filter band. Something like 1khz should work. You will have to play with distance from mic and audio output level. Make sure you are taking these measurements when using a dummy load initially as an antenna that may not be tuned well or at a low swr can cause the output to be unstable. Good luck, -- Nick

KC8WBK
 

One way to increase power output is to increase the voltage on the PA jack. 16 volts seems to work well and will add a few watts to the output.

Frank Dinger , EI7KS
 

Instead of a single frequency audio signal ( the 1 kHz referred to) it will be more effective to use a simple 2 tone audio generator , requiring 2 opamps or a single quad amp  of which 2 amps are used for the 2 (non-harmonic) audio  freq generation and a third for buffering/adjustable output .   Circuits galore on the web .   

Frank , GM0CSZ / KN6WH  in IO87AT