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[KE4ZHN]

$600 is a little bit pricey for an SB220 even if its perfect. But, its a good work horse amplifier if you dont mind the fact that it has no 160 and its that ugly green. I have one of these beasts and use it quite frequently on 75 mtrs. to cut the 20-30 over static crash here in Fl. Unfortunatly they are also quite old now and things break with age. If I had to get an amp tomorrow, I would get one more modern and with 160 capabilities. Relays seem failure prone in many of them I have seen and worked on. The stock design uses open relays and these pick up dirt and crud like a magnet, and eventually cause relay problems. You mentioned that the one your looking at has the mods. The stock zener bias diode is prone to failure too so this is good that yours has the bias circuit mod. All it consists of is replacing the stock zener with a string of common diodes.(Harbach uses 8 600 piv at 1 amp in his string) This is a problem area with the 220 as well. I have heard of bias diode failure. This is a simple and cheap fix so dont let that sway you from this amp. Also, you may want to make sure it has the soft key mod. The stock design has a 110v dc relay and many modern rigs will NOT safely switch this relay so you will need a relay box or homebrew interface to switch the amp. Mine loads up just fine on 12 and 17 mtrs. with no mods, it will lose a small amount of output due to the tank circuit and input circuits not being optimised for those bands but it will work fine. Just use the 15 mtr. tap on the bandswitch and it will tune up on both bands. All in all, the SB220 is one of the best amps for your buck for the power it will give you. You can expect legal limit or very close with a healthy set of 500z`s and it will run for many more years to come as the hundreds of them that are still around do every day and night. Good luck.

                                            73  Rich

[KE4IZA]

     
          I am in need of a linear amp for my TS-830.  I work primarily 10m, 12m, 17, 40, 75m.  I have been offered an SB-220 is extremely good condition with several of Measures mods.  Is this a good amp for $600 or should I keep looking elsewhere.  I would not know a good amp deal if it bit me.

Thanks to all.

[WB2WIK]

The SB-220, especially with the AG6K (and other) mods, is an excellent amplifier; however, remember it's going to be more than 30 years old at minimum (and could be closer to 40 years old) and as such, unless everything's already been replaced, parts will be failing and require replacement simply due to age.  Those parts include the filter caps and bleeder resistors, for sure, but can also include the main power transformer which is not an inexpensive item.

Also, the SB-220's tuned input can be set for a match on 10m or 12m, but not both; likewise, it can be set for a match on 15m or 17m, but not both.  You might try setting it for a compromise (like midway between the optimum 10 and 12m settings, etc) and just use the pi-net in your TS-830S to make up the difference -- which should work pretty well.

And of course, the SB-220 does not cover the band where the most power is usually needed (160m) due to most of us having insufficient space for a truly effective antenna.  

I'd personally opt for something a bit more modern that covers 160m...

WB2WIK/6