SB220 rebuilding help [Archive]

W7NIK

10-31-2008, 06:16 AM

I have a sb 220 that I am rebuilding. Does anyone know how set up the tank circuit. I have the 80/20 coil modified, wire added on the bottom. The 10/15 has been cut and another coil added.
The amp has been mod for the 17, 12meter bands. But the waffer swicth is bad. I am able to set up the input circuit with swr analizer. But how do I test the hight power side? Turn it on slowing add exciter power then see if it tune easly? IF it dosen't tune wrong band swicth on the High power side .
Measure the coil and lenth of wire but where do I find the proper data.
I can set up the tuned input fine but high power side I do not know.
w7nik@arrl.net.

KD8DEY

10-31-2008, 12:14 PM

If A single 3-500z had an output impedance of 500ohms so 2 in parallel would be 2500??

17m 18.068-18.168 so the middle of the band would be 18.118

12m 24.890-24.990 so the middle of the band would be 24.940

According to the W6SAI Book (great book)

for 18.1mhz tuning cap should be 32pf, inductance 2.6uh, load cap 147pf.

for 24.9mhz tuning cap should be 23pf, inductance 1.9uh, load cap 107pf.

Its too early to be trying to think, just got the grandson off to school, no coffee yet. and I'm a no nothing general lite. Soooo

WE NEED A FACT CHECK ON AISLE 2
Aisle 2 fact check please!!:D

KD8DEY

10-31-2008, 12:23 PM

Google is your friend :D

http://www.harbachelectronics.com/

W7NIK

10-31-2008, 04:11 PM

EXCELLENT thank you , How do i verifiy if the coil is the right coil. I have modified original coils that were cut and added too original coils. This was a SK amp wih out docments. I would like to restore it one day . The tuned input no problem.

W7NIK

10-31-2008, 04:13 PM

Google is your friend :D

http://www.harbachelectronics.com/

I am thinking amertitron parts .

KD8DEY

10-31-2008, 07:28 PM

Ocean State electronice sells an inductance tester that you could use to verify/adjust the tap point on what you have.

KL7AJ

10-31-2008, 10:34 PM

EXCELLENT thank you , How do i verifiy if the coil is the right coil. I have modified original coils that were cut and added too original coils. This was a SK amp wih out docments. I would like to restore it one day . The tuned input no problem.

Do you have a grid dip oscillator?