| Author |
Message |
    
Al_lafon
Intermediate Member
Username: Al_lafon
Post Number: 144
Registered: 3-2005
| | Posted on Sunday, January 08, 2006 - 12:44 am: | 
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Hello can someone tell me what i need to mod this amp to class AB i'd like to know what parts to get.
So we can get it full AB for SSB
thankyou al |
Kid_vicious
Advanced Member
Username: Kid_vicious
Post Number: 997
Registered: 9-2004
| | Posted on Sunday, January 08, 2006 - 2:20 am: |
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to disable the preamp,
clip the center
leg (base) of transistor TR3. Add a switch to the cut and it is now selectable (only when power is on). This deactivates the pre-amp relay thus bypassing the preamp circuit. This is also a good temporary fix for a blown TR4 preamp transistor until you can replace it.
To convert to Class AB, isolate the grounded-end of the input transformer (T2 in the schematic, T1 on the circuit board). To do this, I used a Dremel tool and a small grinding bit to cut the ground foil...Use DMM to make sure there is no continuity across the cut. Since there is limmited space, a simple bias circuit needs to be used. For this, I soldered a 100ohm/10w resistor to +Vcc, to the other end of the resistor the anode-end of a large silicon diode..cathode end to ground. At the resistor-anode junction, add an RF choke, the other end of the choke to the isolated tubes of the input transformer. This applies about 1.5Vdc to the basses of the RF transistors keeping them "on"....Class "AB"...ENJOY!
these are from Inspector, and i trust his knowledge,
matt |
Al_lafon
Intermediate Member
Username: Al_lafon
Post Number: 145
Registered: 3-2005
| | Posted on Sunday, January 08, 2006 - 9:48 am: |
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Ok i get the idear but what value choke and diode
do we need or can i just use a part like 100 µH RF Choke from you know who RS and 1N5404 diode
from same little place. Also when looking at my
amp it's got a switch that gives ( up ) amp and preamp ( center ) all off (down) preamp only.going to look at this more for preamp mod for switch.
Thankyou for getting backto me AL
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Chad
Advanced Member
Username: Chad
Post Number: 633
Registered: 11-2004
| | Posted on Sunday, January 08, 2006 - 11:20 am: |
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Yeah I'm lost on the choke value too. I tried to e-mail the Inspector to no avail, it bounced back
Chad |
Kid_vicious
Advanced Member
Username: Kid_vicious
Post Number: 998
Registered: 9-2004
| | Posted on Sunday, January 08, 2006 - 10:05 pm: |
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you guys have discovered the reason that i have not modded mine yet!
where are you inspector?
i kinda hoped that bringing this topic up again might produce some results.
keep hope alive,
matt |
Inspector
Intermediate Member
Username: Inspector
Post Number: 155
Registered: 12-2001
| | Posted on Monday, January 09, 2006 - 4:06 am: |
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Hey, Gang...About a 3 or 6Amp silicon power diode can be used as it is used to generate about 0.7 to 1.5VDC to be added to the pills' basses, turning them on. The Choke can be any RF choke, either wire-wound or an RF ferrite-bead or toroid wound with about 4 turns wire...just to keep RF off the VCC (+12VDC line). |
Inspector
Intermediate Member
Username: Inspector
Post Number: 156
Registered: 12-2001
| | Posted on Monday, January 09, 2006 - 5:58 am: |
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Hey, Gang...About a 3 or 6Amp silicon power diode can be used as it is used to generate about 0.7 to 1.5VDC to be added to the pills' basses, turning them on. The Choke can be any RF choke, either wire-wound or an RF ferrite-bead or toroid wound with about 4 turns wire...just to keep RF off the VCC (+12VDC line). |
Chad
Advanced Member
Username: Chad
Post Number: 638
Registered: 11-2004
| | Posted on Monday, January 09, 2006 - 9:06 am: |
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Thank you sir! Mouser order being placed today, just in time.
Chad |
Al_lafon
Intermediate Member
Username: Al_lafon
Post Number: 151
Registered: 3-2005
| | Posted on Monday, January 09, 2006 - 9:55 am: |
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Thankyou Inspector! Hay Mouser better stock up
your diodes and RF chokes (HiHi). |
Kid_vicious
Senior Member
Username: Kid_vicious
Post Number: 1007
Registered: 9-2004
| | Posted on Monday, January 09, 2006 - 10:37 pm: |
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chad, did mouser ever send you any of the IRC520's?
(i think that was the #)
just want to know how they worked for you.
matt |
Chad
Advanced Member
Username: Chad
Post Number: 640
Registered: 11-2004
| | Posted on Tuesday, January 10, 2006 - 9:20 am: |
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Never got the chance to order, Had a mass suicide of home appliances over the holidays that sucked up my free time and cash 
Should get rolling on it soon, very soon
Chad |
Hollowpoint445
Senior Member
Username: Hollowpoint445
Post Number: 1004
Registered: 6-2004
| | Posted on Tuesday, January 10, 2006 - 7:27 pm: |
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Um, what? LOL Was it a ritualistic approach, or was it just monkey see, monkey do? |
Chad
Advanced Member
Username: Chad
Post Number: 644
Registered: 11-2004
| | Posted on Wednesday, January 11, 2006 - 10:10 am: |
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I don't think it was monkey see as much as premeditated. Garage door opener, drier and stove. Along with a range hood (old one did not "match" BLAH), and parts to re hang the garage door. Spend my vacation on a ladder or under something, oh well
Chad |
Kid_vicious
Senior Member
Username: Kid_vicious
Post Number: 1017
Registered: 9-2004
| | Posted on Thursday, January 12, 2006 - 11:26 pm: |
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chad, dont you know that if the teacher sees that you CAN get straight A's; then she's going to expect them all the time?
just kidding! i bet you couldnt do a half a$$ed job if you tried. i know i couldnt.
i just got engaged on christmas eve and i already stink at doing dishes!
i used to be good at it, but that was when no one was looking.
hey, i dont have to run a spotlight at work because i keep telling them that i stink at it.
can you imagine if i actually had to PAY ATTENTION during the show?
have a good weekend my friend,
matt |
Chad
Advanced Member
Username: Chad
Post Number: 650
Registered: 11-2004
| | Posted on Friday, January 13, 2006 - 9:32 am: |
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I'm a sound guy I don't TOUCH lights, I don't even want them on the same distro!
She's a good girl and can acutally swing a hammer with the best of them. Daddy was a carpenter and she loved to help. So I don't mind simple appliance repair/installation. Re-hanging/balancing that huge steel door was no fun though! Thing has 480Lbs of tension on it to balance it out :>0. |
