3 Bias Circuits Explained For RF Amplifiers Using 2sc2879 Transistors 

Im glad i could help ya brother 🙏 if you need any transistors at good prices shoot me a text 678 557 4846

No problem bud!

No problem buddy thanks for stopping by.

No problem buddy...want to pay me back...share this on your FB or anywhere you can.

Thank you brother!

Hey 1883 could you send me a list of all of the capacitors, resistor’s, and all the other things that I need to build a amplifier? I just need to know what to order lol. If you could I’d appreciate it very much. 73s buddy.

@@rodneymclemore8587 send me and email lets talk threemanpro at gmail dot com Or text me 678 557 4846 well go from there

Gate,you should make some vids on what you covered in all these videos,but on DVD format.I would love to be able to watch these anytime l wanted on my TV w/o using my phone data.Nobody on youtube ,that l have seen,cares to share the knowledge you have with us.Thanks so much man,your videos have helped me understand these amps alot more.👍 I would like to see some vids on troubleshooting common problems with old solid state amplifiers.I have a TX-150 l am struggling with at the moment.l may end up rebuilding the whole dang thing like you did on your 150,😜.Thanks,Grunt.

1883 excuses to many

​@@gruntohseven5803ooooooooh good idea man really good idea!!!! That is am amazing idea Imma do it

Your very welcome 🙏

I will bud gonna be releasing some repair videos soon

No problem bud...make sure to share with your social and friends that may be interested.

Exactly right....the rf will do that...that is why you need to choke it off with 10uf to 22uf. Ill do more at times to make sure no rf goes back lol. Or atleast keep it low But you want to use a high permeability ferrite... I use 43. Thanks for stopping by and leaving a comment brother.

I actually made this video 3 and 1/2 years ago to help our mutual buddy while he was beginning to learn to bias. I am not sure if he has picked up on it yet that this is the video that I made for him yet....Imma wait and see if he comments lol.

Dood you are one smart joker man....I am very forchinate to have you on my comments lol...id love to chat with you one day on the phone I think we would enjoy our nerd talks lol. You have a lot of knowledge and im pretty sure you have been In this longer then I have. I am just guesing..would you be up for a chat sometime..if so email me your number and my procrastinating ass needs to reply yo your last ones dammit 😒

I would love to see it when you do bud.!!

No problem bud.

Their are circuits right there buddy. Just take your pick and make the circuits by them selves and test away from amp.

Non biased class C works fine with AM or FM, SSB need 0.7 volt bias to sound not distorted.

You couldn't have said that any better...EXACTLY RIGHT!

On your actual relays coil(snubber diode) just a 1A Diode like a 1n4001 will suffice. If you really want to feel safe just get some 1n4007 and be done with it. :)

Sounds like a keying transistor or cap on keyinging circuit some times it is best to replace everything in the circuit and be done lol. The tube amp is beyond my knowledge I don't understand tube amps but really want to learn.

@@1883GotDown thanks you 73's

Pretty much the divider in the class b are the two 10 ohms on the base in parellel.

Correct! You use a class c on ssb as well but of course bias will allow yout actual audio to be the same as the actual audio coming from your radio

Very very good question. Yes I have used these before and it does save time & wire using these so you can use one Pole for the bias. It is honestly a good question. Maybe some people would rather keep there AC and DC separate. It could be that they buy the DPDT relays in bulk and use one of their smaller relays for the bias relays. There has been times I honestly didn't think about it lol & I could have used a 3PDT instead. I have maybe 4 or 5 of these left and I need to use them. Really good question bud.

Thanks bro. I just thought it fascinating that no one uses them .it just made sense to me to use a 3 pole instead of adding another relay as you use the 3rd for supply volts. I have a few 3pole relays here and I got then for the same price as the dpdt ones. Maybe because there not as popular ? I don't know. Thanks for answering Gatekeeper. Take care my friend. Best 73s.... Your UK bud until the end .👍

@@worldradio456uk5 Glad to have you in the UK 🇬🇧 viewing my channel. I'd love to have a lot more viewers from the UK. Bring me some more UK viewers lol. Ive often wondered how the 11m scene is In your area. Does people mostly use FM or do they operate AM on the regular 1-40 channel? Or do they mostly work freehand USB?

Hi Gatekeeper. In England we can use all modes now as am and ssb had finally been legalized a few years back. I've had a few good contacts on AM myself but am a big ssb lover. As you know because we spoke a few times in the last solar cycle 🤣. Localy we chat either FM but usually ssb . We are all waiting like everyone else is for the big cycle to really start up again and really do hope we can all talk to each other across the pond again . Take care bro. 73s. Wr456. UK

Correct! Just make sure to remove the choke that goes to ground

That almost sounds like RF is getting in your meter...that is why I like to use a Fluke Meter they do well with RF in thr last I had go wrap my leads well... but when you key with RF you should get around the same with out RF but it can change once things heat up.

@@1883GotDown I use a fluke 117 and have a choke on my leads

@@1883GotDown when the bias is off the only reference to ground for the input transformer is through the 5ohm resistor and the diode right. Cause when wired directly to ground it's class c. What I've noticed is that when bias is off and it runs through the resistors it actually makes less power than actually being soldered to the board in direct class c. Have u ever noticed the biased boxes make less power than the class c boxes even when the bias is off? When the bias is off and I check voltage at the 5 ohm resistor it's actually -0.45ish volts depending on drive. I just want to know if I'm doing something wrong or if this is Normal. From what u said sound like it's not normal so now I need to figure out why my measurements that seam rock solid aren't correct or there is something else going on. I appreciate all the help. All the knowledge your willing to show in your videos will keep this hobby alive.

@@1883GotDown ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-71N6f_BCVeQ.htmlsi=bmPJfVGZI8Lsl7yt

@@electromechanicalstuff2602 well a biased amp will do more power with less drive meaning it will do a bit more power let's say with 10w drive while a class c needs to be drove a bit harder till it gets to the same output. Now IDK what 5 ohm resistor your referring to...im not sure which bias circuit you are using your self. Like I mentioned RF will get in your meter when trying go test with RF present also...before I got a good meter I had go gorilla force wrap my leads like crazy to keep rf out of my meter. You should be able to dry key and get your 0.38 to 0.42 if b bias or 0.62 to 0.68v and should get the same exact reading if you do a carrier and check it. With you getting a neg(as if your have your leads backwards on a dc signal) its seems as if your meter is seeing the AC signal from your RF. Just check from the back of your transformer to ground. But when it comes to sources to ground....it has the diode and the 10 ohm resistors on each base. They are part of the bias circuit as well. Now if you try to use the amp in bias mode with it off the amplifier isn't going to work as well cause it is in class mode then with no direct couple to ground all it has is the 10 ohm resistors. Class will do the most power with less current with out linearity and a biased amp will give o soem of its top end power for linearity but will pull much more current but like I said a biased amp will get up and go with less drive since base is open more already then if it was class c which uses the rf to open the transistor. Hope this helps man im not a genius eith this stuff by no means. I'm wondering why your curious what it is doing while your talking I guess your just wanting to make sure that its working correctly..as long as your wire is thick enough and have a good B+ going to the bias circuit then ur good. It can be real real tuff to see the DC voltage with rf mixed in

Reading in DC it doesn't matter....It can be read anywhere after your bias circuit. Meaning at the base of the pill, back of transformer etc..... If your keying up with RF present then its a good idea to check after the choke..that is why that choke is there to minimize the rf going that direction.

I've already explained the full situation to you and you won't be a man and speak with me on the phone so I can show you your case and all your parts is outside waiting for after this 2x8 base ive worked on for 3 days now... you took me you were ok waiting till your actual turn instead of me doing it ahead of others last time we spoke. All I ask is for you to chill let me get this 2x8 done and if you see that I'm not deliver you can have your way with me...heck ill design you a bot where you can comment bomb me 24/7....all I'm simply asking is to chill for a bit longer and let me get this guy out of the way please brother please 🙏