Rebuilding an SB-220 (for KJP)

Discussion in 'Amateur Radio Amplifiers' started by W1QJ, Jan 19, 2013.

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  1. AF6CO

    AF6CO XML Subscriber QRZ Page

    I didn't see them listed in the parts section of their website. I'll call them and see if I can get a pair.
  2. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    I don't know who has them, but I see them on eBay all the time, from commercial vendors who I can identify, so I just contact them off-line and buy them. Ameritron uses them in their amps, though, and might have a very good price on them.
  3. AH6RR

    AH6RR Ham Member QRZ Page

    Do you use the pointers also? My 220 I did use the 2" Knobs from MFJ but will it throw off the indexing with the 6:1 ratio of does it track where it should be? Because since I do have mine on the bench now I would like to add these to the amp. I did check all the HV filter caps last night and each and everyone of them were 245mf with my B&K capacitance meter so it was just the transformer that went south well thats all I found so far I will check the Rectifier/Metering board tonight.

    Roland AH6RR
  4. W1QJ

    W1QJ Ham Member QRZ Page

    Roland, If you disconnected the secondary from the rectifier and the fuse blew the tranny is shot. I have seen this several times before. The diodes on the rectifier board can easily be checked with an ohm meter on the diode check option. You don't have to disconnect anything. They can be tested right in the circuit. Same with the zener. It too can be tested in circuit. If you have the stock 1 amp diodes you can upgrade them to the 1N5408 3 amp jobs. You have to enlarge the holes though which could require taking the board out. Makes it much easier. If you would like a set of the 1N5408's let me know, I have them. I can throw a set in the box with the tranny. Today was a holiday so I could not mail it out. Hopefully I will get to it tomorrow. I mentioned in the beginning of this thread I installed a new Peter Dahl transformer in the unit that I am fully rebuiding for a customer. I fired it up and I am seeing about 300 volts more on the HV then with the stock transformer. I installed one a few years ago and the HV was the same as the stock transfomer. I wonder if they upped the HV? However in the CW mode the voltage is the same as stock. The top perforated cover needs to be relieved because the PD transformer is about 3/8" higher than the stock tranny and the cover lumps up badly unless you relieve the cover. I had my buddy cut a nice clean relief with his Bridgeport. As far as rewinding the stock transformer, only certain people can do this. The Heathkit transformers are very hard to rewind. The guy who rewound other transformers for me tried the SB-220 transformer and gave up. Not sure why though. Something to do with the potting I think. Lou
  5. W1QJ

    W1QJ Ham Member QRZ Page

    Steve, Ameritron is very good about selling the parts that go into their amps. I wonder why vernier drives are not listed? I haven't tried asking them but I am pretty sure I have a pair of them here someplace. Problem is finding them.
  6. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    Lou, I've found them on line a lot. Maybe a phone call to Ameritron would reveal the big secret.

    I'm sure you remember "Jackson Brothers" vernier drives, they were never expensive and worked well. They're out there!

    Might have been a British company, I don't really remember. Eddystone was British, I'm pretty sure, and made all our dial drives for Venus/Zeus/Interceptor products when I was with Clegg a long time ago. I think those drives used to cost $18 back then and people loved them.
  7. KB2FCV

    KB2FCV Ham Member QRZ Page

    Not exactly sure what KJP's problem with. Lou has helped me get my SB-200 up and running. When I first got it, he was able to supply me with a missing meter cover.. I think it cost a whopping 8 bucks plus shipping (a couple dollars more). He also fixed that same meter later on when it was having problems sticking. The cost? The price to ship it back. It was extremely generous to Lou to spend the time to repair the meter and get it back to me (with a fast turnaround time too!). Lou is an asset to the hobby as he knows these amplifiers inside and out and has aided countless hams getting their heathkits back on the air. Like another thread, he replied both times offering his services to me. After reading KJP's posts, I think he's way out of line... expecially with the personal attacks.
  8. W4PG

    W4PG Super Moderator Lifetime Member 279 Volunteer Moderator Platinum Subscriber Life Member QRZ Page

    So let me get this straight.

    If I have an SB-220 amp and get help to modify it so it works on the 6 meter ham band, that mod is illegal?? How about if I just homebrew me a 6 meter amp from parts in my junk box??

    Am I missing something here?? I'm so confused . . . . :)
  9. WA7PRC

    WA7PRC Ham Member QRZ Page

    I've never found my SB-220 to need vernier drives, even on 20/17/15/12/10m. Without vernier drives, it takes me only a few seconds to tune up, and I don't consider myself to be particularly dextrous.

    However, I agree about Lou. :)
  10. WA7PRC

    WA7PRC Ham Member QRZ Page

    Most parts aren't listed online -- you have to look in the catalog or call/email. They're in the current catalog, page 82. PN 729-0142-1 for the drive ($11.92 each). PN 726-0227R (1-1/4" long, $1.55 each) and 726-0230R (1" long, $1.25 each) for the pointers. If you can tune your amplifier w/o them, consider saving yourself the time & expense.
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