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Message |
    
Sp5it
Junior Member
Username: Sp5it
Post Number: 17
Registered: 10-2006
| | Posted on Sunday, February 15, 2009 - 4:08 pm: | 
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http://www.rmitaly.com/download/manuals/KL200-manual_rel_201.pdf
Can anyone help me to bias this little amp? C-class sounds bad on SSB.
Mike |
Drzuo
Member
Username: Drzuo
Post Number: 88
Registered: 1-2006
| | Posted on Monday, February 16, 2009 - 8:13 am: |
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Hi sp5it, That amp is tiny and there probably isn't enough room to do it. There is also the bang for buck aspect. A few things to consider. 1) the amp will require less drive as a class ab amp, being a single "pill" you'd have to drive it even lower than you do now. 2) it will draw more current as its efficiency will drop, probably an extra 2 amps at its level. Depending on your skill level you could damage the amp. With that being said here is what I would try, if it were me and I was just bored as hell. 1) you need to put a 2nd relay in (12v 1 amp contact spst or spdt leaving the one terminal open) this is to switch the bias voltage. I would parallel it with the main relay. you would have to be sure tr1 the relay switching transistor could handle the current. Lift L2 from ground this will be part of your bias filter. The blue circuit added is a de-generative feedback, which will help keep the amp from going into oscillations. Every thing else added for bias is in red. The 35 ohm 5 watt resistor is a "brick style. The diode is a schotkey. Before the circuit is attached to L2 I would sample the voltage you are about to apply as being no more than 400 micro volts (.4 volts)and no less than 250micro volts. it will drop a bit as it connects with the circuit. changing the schotkey diode will change that, also changing the 1 ohm resistor to a 2 ohm will lower the volatge in case you get a reading of like 600micro volts or something. Only then would I connect the lifted end of L2 to the new bias circuit. I did this quickly while getting ready for work, and the pic is a little fuzzy, i can send a better one directly to you, if you still wish to proceed. but this gives you an Idea of what to expect anyways. If this is your only amp I would not do it, but use this as a case in study comparing to other amps. if this is something laying on the bench have fun, this is how you learn. |
Drzuo
Member
Username: Drzuo
Post Number: 88
Registered: 1-2006
| | Posted on Monday, February 16, 2009 - 10:00 pm: |
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I can see the pic didn't go through, I'll try again.Sorry Lon it has to be a little bit big so he can see it. CLICK HERE > KL-201 |
Sp5it
Junior Member
Username: Sp5it
Post Number: 18
Registered: 10-2006
| | Posted on Tuesday, February 17, 2009 - 1:29 am: |
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Thanks for the answer. Try to post your pic on imageshack.
Mike |
Drzuo
Member
Username: Drzuo
Post Number: 88
Registered: 1-2006
| | Posted on Tuesday, February 17, 2009 - 7:12 am: |
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ok i posted it twice, it not that big of a pic(20k), the link is not the pic i posted, mine has the mods drawn in. If youre still interested, let me know ill send directly. even the physical size of it is smaller than some of what i've seen posted. |
Tech808
Moderator
Username: Tech808
Post Number: 16603
Registered: 8-2002
| | Posted on Tuesday, February 17, 2009 - 5:04 pm: |
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Copper Forum Member's,
The Copper Forummaster has created a Specific area for you to Submit/Post your Pictures.
It is titled: Members Pictures
By submitting your pictures to the Members Picture Area you can direct other Copper Forum Members to view all of your pictures submitted/posted under your Copper Forum User Name. 
And this also help's the Copper Forum Moderator's & Tech's as the Copper Forummaster Created and Approves submitted to this Topic Area.
This also saves other Copper Forum Members from having to scroll back and forth across a page to read a topic & other post's.
Hope this help's,
Lon
CEF#808~HAM#001/N9CEF
CVC#002
Tech808@copperelectronics.com
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