EMRFD Message Archive 9778

Message Date From Subject
9778 2014-02-23 03:34:22 Ashhar Farhan An RC-coupled Linear Amp
I just finished a linear amp that is entirely RC-coupled except for the power stage's output. I have built two of them and they appear to very quite stable and clean. It uses just the 2N3904s  in the chain except for the power output stage.


It started with the a stupid question "Why can't the LM386 be used in an RF linear?"

I am particulary curious to know what value should one pick for the 100 ohms in the Q4. I am quite kicked by the one-line band-switching arrangement.

- farhan
9783 2014-02-23 12:11:15 Todd F. Carney / ... Re: An RC-coupled Linear Amp
9784 2014-02-23 16:52:56 ashhar_farhan Re: An RC-coupled Linear Amp
Todd,
I understood the arrangement of the push-pull after a slow reading of your pages on audio amps. My 465 didn't show the cross-over glitch. So, I am not sure of the distortion figure.
I will put the measurement receiver together after I clear the table of the Minima's trail of trash/junk.
The connection to LM386 is a little roundabout. I have been looking for a small rf amp that one could drop into various projects without thinking too much about it, and with a minimum 'external part count'. I even tried driving the LM386, TDA2003 and the LM380 with RF to see if any gain is possible (none, though the 74LS14 surprised). This is sort of an RF brick that one drops into various projects.
- f
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9785 2014-02-23 17:33:54 Todd F. Carney / ... Re: An RC-coupled Linear Amp
9786 2014-02-23 17:35:34 ashhar_farhan Re: An RC-coupled Linear Amp
Todd,
I was refering to you audio amps. This linear's heart is the popcorn audio amp!
- f
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9787 2014-02-24 10:45:49 Sandeep Lohia Re: An RC-coupled Linear Amp
On 24/02/2014, farhanbox@gmail.com
> I have been looking for a
> small rf amp that one could drop into various projects without thinking too
> much about it, and with a minimum 'external part count'.


give a try to 'BGY588' can send for R&D before end of this week...
9788 2014-02-24 11:08:24 Dana Myers Re: An RC-coupled Linear Amp
9789 2014-02-24 15:26:22 ashhar_farhan Re: An RC-coupled Linear Amp
Dana,
With 6v peak to peak, I am getting slightly more than 5 watts and the current draw of the IRF510 is 950.ma.
The distortion is expected as the transistor is being used in AB1 class, hence the low pass is needed to clean it up.
- f
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