SGC-230 relay replacement

A common fault on the SGC range of antenna tuners is a reduction in receive performance as they get on in years. This can be attributed to contamination on the relay contacts since SGC stoped using fully sealed relays. Any small condensation inside the tuner makes it’s way into the relays and causes contamination on the contacts as they are hot switched. The best thing to do is to replace all 26 relays with new units…

You can see the contamination on this relay with the top case removed.

The PCB has to be removed from the case to access the underside and remove the relays. It’s not a hard job but you have to be careful not to apply to much heat and risk lifting the PCB traces.

All 26 contaminated relays removed.

You can easily see the damage to the contact in this picture.

New relays ready to go in. I used Panasonic ALE1PB12 relays. They are rated for 16A which is a little higher than the original SGC part which was 10A.

All new relays installed.

Does it make a difference? Yes, very much so. I tested before and after and can see up to a 9Db difference in received signal strength across the board. I dare say it will also handle a little more power now with higher capacity relays (original rating is 150W) but I don’t know if the other components will like it! A job well worth doing to extend the life of this great tuner.

19 Replies to “SGC-230 relay replacement”

  1. Hello.. thank you for documenting this fix. However, I’m having
    a heck of a time finding those Panasonic relays. Any other
    details that you can share for finding another substitute?

    tnx.. Fernando N2FQ

  2. Hi Mike.

    I’m not 100% sure on the original part number (a question for SGC maybe?) but I do know that the Omron G2R1-A is a direct analogy of the SGC part.

    I hope that helps.


  3. Hi Fernando.

    You can also try looking for the following compatible relays:

    Panasonic ALE1PB12 (The ones I used)
    SCHRAACK RP83012
    Omron G2R1-A

    Good luck.

  4. Thanks for this fix. I got one and the fellow mentioned it was a little flaky and it turns out there is a bum relay

  5. Hi Hello
    I live in the Republic of Korea.
    My call sign is DS2RSB.
    I have read the relays exchange article of the SG-230 Smart Tuner well.

    1, Can I disassemble and clean the relay?
    2, Can I use Taiwan’s product relays?
    I wish you luck always.

  6. IIRC, you can take the case off the top of the original SGC relays but I don’t know how well they will clean up. You can use any relay that has the same (or better) spec and footprint/pinout.

    I hope that helps.


  7. Matt
    Just come across your site and wonder if you would be kind enough to answer a simple question re my (very old) sg-230. It has just simply stopped working. Checked all and found DC short on input (259) connector. Before I start ripping things apart – I would like to know whether a DC short on the 259 would be ‘normal’

  8. Matt
    I’m not sure if I need to place my data/request in again (having been ‘moderated’.)
    Anyway – I want to know whether a DC short would be expected on the PL259 plug of the sc230 (thats what I’m getting and a high SWR indicated). Replacing the sc-230 with a dummy load at the mast end of the coax feed gives a very favourable SWR !

  9. Hi David.

    I’ve just got around to reading your comments. Lucky for you, I happen to have a 230 on the workbench at the moment having just undergone a relay replacement and full test. I’ve checked the 259 and it does show a dead short at DC both when powered on and off.

    You should get a nice audible “click” when you power the 230 on. If not, the first place to look would be in internal fuse. I hope that helps.

  10. Hello Matt (?)

    Many thanks for the speedy reply.

    I can confirm the observations – including the click on application
    (and removal) of power.

    Subject to Wx, I’ll take my novaVNA out this afternoon and see what
    it says – I assume it should be 50 Ohm resistive ?

    73 and thanks again.

    Dave gm3yew

  11. Hello Matt
    I didn’t see my reply appear on the site – so here is a precis – I have now used my nanoVNA at the shack end of the coax feeding the tuner. It seems to indicate a very satisfactory 57+j0.3 (if my calc was correct. Unfortunately, due to high sunlight yestrday, I was unable to see the screen outdoors, but I have replaced the tuner with a dummy load with a very acceptable swr in the shack. The application of power gives a very satifactory click. I assume the DC short circuit is some form of lightening protection ?
    Do you repair these devices ?
    73 dave gm3yew.

  12. Hi Dave.

    I don’t undertake repairs for the public, sorry. If it’s powering up and you have checked the coax, the next test would be the “Lightbulb test”. You can find details here:

    I’ve had 2 in the past that behave as you describe where the fault has been a dead diode pack and binary counter. Both fairly easy to replace. Do you have the older “through hole” PCB or the newer surface mount version?

    Let me know how you get on.

  13. Hi Matt, I’ve just seen your article regarding relays. As I have a similar age to yours (7 red led’s), I was wondering if you may have a service manual or at least a diagram for it. My unit suddenly stopped working ( no tune after power up ) and fwd led not lit when RF applied. I found 3 open circuit sensing diodes and replaced to cure unlit led. Still no tune though. Short of replacing standard IC’s and keeping fingers crossed, It would be very handy to be able to follow circuit path. Best wishes Paul

  14. I had a blown relais in SGC Smart Tuner SG-231 too.
    The original relais in the device are labled SGC 591-110.

    They do look really similar to the OMRON G2R-1A-E-DC12 — BUT if you look at them very closely, there is a difference: The distance between the moving “tongue” of the relais and its counter contact is bigger in the SGC version that in the original OMRON version.

    I wonder if that could create little arc’s when high tension is applied.

    Anybody got feedback on using the OMRON G2R-1A for a while?

    Siegfried DG1SEK F4VUH

  15. Tnx for your inputs so far. I have a SG-239 that stopped tuning. Hopefully it is not the processor – to replace the processor is almost impossible.
    De Rolf, DL8BAG

  16. @Siegfried DG1SEK F4VUH:
    Did replace about 10 relays with OMRON G2R-1A-DC12 many (>10) years ago. SG-230 running fine still today.

    73, Markus HB9BRJ AE6MG

  17. Thanks for a great write up. I see that the Panasonic Relay you recommend is no longer manufactured. Do you know if the Panasonic ALZN5B12Wwill work?

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