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2pill 2sc2879 amp build

fodendaf

Active Member
May 2, 2009
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I'm starting my first amp to have something to do for the winter nights. Here's a few pics showing current progress which is not a whole lot but I did mess up one hole when I tapped it too deep and the tap went sideways. I had to drillpress another set of holes elsewhere and tap them. Parts are almost all from icamanufacturing but I did forget to order a few so it won't be completed fast. I'll try to get it ab biased as ssb is all I ever use now.

In the power supply case is an antenna switching arrangement I made to run low power on tx and relay switched via transceiver relay to straight thru on receive. The 14db attenuator with 4watt dummy load mounted on a stub of coax with pl259 is pictured. I mainly made it just to experiment with low power but I can also use the switch to run a separate antenna on receive as I mean to erect a beverage some day.
It might be of interest to those that run radios with an alc spike into linears to make one of these with the attenuator rated to 100w pep.
 

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good stuff. if you have any comments about not making expensive mistakes or such don't hold back. It looks like I'll have to get a 60 watt soldering iron as my 30 watt is giving cold joints on the pcb.
 

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what wattage or iron model do you recommend? ica has the hakko936 on their site but i've been looking and i cannot find what wattage it is. Also I understand hakko only sells 110volt models in the US market. I only have 230v in ireland. also what mix of rosin and flux in the solder should I buy? I bought silver solder before and it was terrible, made every pcb greasy so the solder wouldn't stick.
 
I got my 70watt chinese thermostatic soldering iron today Freeshipping Thermostatic Soldering iron MT 3927 70W 220V-in Electric Soldering Irons from Industry & Business on Aliexpress.com so here's a pic of the progress. I had some difficulty sourcing a metal clad 820pf cap so I used this russian one. One fell apart when soldering so I took a look in and it's metal clad inside. Hopefully it'll hold up.
Also the tip is from the new iron. Given that the hakko936 is the most widely cloned iron does anyone think those tips will fit this when it burns out.
 

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I was happy with the results but it's hard to repair the mess I had already made around the pills. My solder is really bad quality that I have had complaints about but so long as I have no shorts I'm good to go. Anyone know what value of cap to use for ssb delay?
 
I was happy with the results but it's hard to repair the mess I had already made around the pills. My solder is really bad quality that I have had complaints about but so long as I have no shorts I'm good to go. Anyone know what value of cap to use for ssb delay?

If your keying it with the transceiver relay....why do you need the Delay Cap?

Good thing to have for cleaning and reworking solder Joints
Solder Wick!...yes you need a better iron...I prefer a variable Weller with a chisel tip for that kind of work....
Fine tips are good for board work, but not enough surface area for what your doing IMHO
All the Best
BJ
 
I agree. you need a high heat iron so you won't end up lifting off the traces. Just remember to have the transistors greased good and bolted down to bleed off the heat when you solder them. if not you could distroy the transistors.
 
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Because I'm going to drive it with a cb to tune it up with initially and run for a while. I really don't want to blow up my new ts480 with an unproven amp but I wouldn't feel as bad about losing a 20 year old cb. I had built the keying circuit already and it was putting a dc between the input pl259 and the floating chassis of the cb.
 
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Is it okay to use a type 61 ferrite on the choke of the output transformer or should I use a ferrite from a pc motherboard that is designed for supressing rfi?.
 
It'll have to do now. I'm not about to buy another iron for just one amp. It's gone too far over budget as it is. I used about 1650uf for the ssb delay after different sources advised between 470uf and 2300uf. I won't try it out for another month or so as I want to install negative feedback at least before I start tuning and the slow boat for parts is slow. I differed from the input of the two pill small case by using 4 wraps and no variable pot so hopefully It won't cause too much headscratching. I plan to improve the grommets around the input cables to prevent fires by drilling a different hole but I tried to cut corners using the 5mm grommet with the 5mm cable and it didn't work out.
The design called for 3 wraps on the input. Will going to 4 mean the capacitance across the input transformer will go up or down?
 

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