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Author Topic: Siltronix 1011 B Question  (Read 3232 times)
KD5TGN
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Posts: 36




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« on: February 23, 2011, 05:17:13 AM »

Last evening a friend brought his Siltronix 1011 B to a CAP meeting to show me. It looked great, a bit dusty but in very good condition. We powered it up (120 VAC) and the magic smoke escaped from the left rear corner of the rig. It seems that is where the power supply is, along with two tubes.  Now I have *no* experience with tube driven rigs... what is the best way to start the trouble shooting, and repair of this radio?

Thanks,
Dan
KD5TGN
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AC5UP
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Posts: 3927




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« Reply #1 on: February 24, 2011, 09:18:30 AM »

1) Get a copy of the schematic / service manual: http://www.radiowrench.com/sonic/sil1011b2.pdf
You can find more Siltronix info here: http://www.cbtricks.com/radios/siltronix/index.htm and more than you'll ever need to know here: http://www.radiowrench.com/siltronix/

2) RTFB, especially the sections on theory of operation and circuit descriptions. This may seem like a waste of time when you're anxious to get started, but at this stage of the game a pint of understanding can save you a gallon of troubleshooting time later. Working on the rig while you're clueless is the express lane to nowhere.

3) Power supply problems are relatively easy to track down. Typical circuit involves a fuse, switch, transformer, rectifier and AC ripple filter. Open up the chassis and give the smoky corner a good look. Like you mean it. With a flashlight. Both eyes open. Anything burnt? Fuse still good? Check the power switch with your ohmmeter across the switch contacts and from the switch to chassis ground. Unsolder or otherwise disconnect the transformer from the rectifier(s). Do the secondary windings still have continuity? Disconnect the rectifier(s) from the electrolytics and check them for conduction forward and reverse with the diode check function of your meter. If all OK so far, re-connect the transformer to the rectifier(s) but NOT the filter electrolytics. Put some fire in the hole (and be prepared to kill power muy pronto if the radio barks at you). AC volts coming off the transformer OK? Unfiltered DC volts coming off the rectifier(s) OK?

Note: Confirm that your meter can handle the anticipated HV before measuring. Many meters are rated at 1,000 volts DC but only 600 volts AC.

4) If all OK you have what's probably the most common power supply failure... A shorted electrolytic. Next most likely failure is a shorted rectifier which can smoke a diode bridge - or - open a winding in the transformer secondary. You don't want to know what a replacement transformer costs.

5) You can test electrolytics (quick & dirty) with the 2k or diode check function of your meter. Measure the resistance across the condenser. Should start out very low then slowly rise to infinity. If it stays low it's shorted and needs to go. If it rises to infinity quickly it's only a fraction of the rated capacitance and needs to go.

6) If you find nothing wrong with the power supply it's time to move downstream in search of a partial short... Good Luck!

BTW: Considering the age of the radio it wouldn't hurt to rebuild the supply while you're in there. HV diodes typically used at the time were in the 750 to 1000 mil ballpark, today you can buy 1000 PIV 3 amp jobbies for pocket change and it's criminal not to upgrade them. And, speaking of criminal, you do know the Siltronix rigs were a favorite on the criminal band back when CW McCall still had a career... Don't be surprised if the rig has been modified by a Freeband Bubba.  Tongue
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KB4QAA
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Posts: 2450




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« Reply #2 on: February 24, 2011, 11:04:07 AM »

I must say that I gained a much better appreciation of the Swan/Siltronix lines after reading the link to Radio Wrench's excellent articles.  Definitely a great read, and fills in some history I didn't know.    Thanks.

Bill
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AC5UP
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Posts: 3927




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« Reply #3 on: February 24, 2011, 02:57:02 PM »

Imagine you're the marketing director for Siltronix.
What's the most attractive model name you can imagine for their top of the line SSB CB transceiver...?

http://www.cbtricks.com/radios/siltronix/ssb23a/ad/graphics/cb_mag_oct_1975_pg59.gif

Nope. That's not it. You're fired.  Grin
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W8AAZ
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Posts: 359




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« Reply #4 on: February 24, 2011, 03:47:36 PM »

About time to get it fixed, with sunspots getting ready to come back and the band to open up. Maybe get it fixed just in time to work some good DX.   My question of the day-why do all CB radios have a PA function built in?  Is it so you can drive around, and announce, "Hey there, I am an official CB operator and stand by for some sort of announcement!" 
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K9FON
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Posts: 1012




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« Reply #5 on: March 01, 2011, 11:35:29 AM »

About time to get it fixed, with sunspots getting ready to come back and the band to open up. Maybe get it fixed just in time to work some good DX.   My question of the day-why do all CB radios have a PA function built in?  Is it so you can drive around, and announce, "Hey there, I am an official CB operator and stand by for some sort of announcement!" 

HA! I ask myself that question myself!! Even the big base radios that are far from being used mobile have a PA function.

The 1011 is a glorified CB from the CB boom years and at best it is pure junk. It drifts worse than an untied boat and the best place for it is the junk parts bin. The final tube is worth more than the rig itself...
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AC5UP
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« Reply #6 on: March 01, 2011, 02:20:04 PM »

Not to play Devil's Advocate, but from a purely capitalistic point of view can you blame Swan for jumping into the CB market? HyGain did it, as did E.F. Johnson, EICO, Heathkit (who could forget the 27 MHz Benton Harbor Lunchbox, AKA The SquealMaster 11?), Gonset, and many more...

Amphenol? Yeah, Amphenol......... http://www.cbtricks.com/radios/amphenol/510b/ad/graphics/s9_mag_jul_1965_pg23.gif

Et Tu Hallicrafters? http://www.cbtricks.com/radios/hallicrafters/cb19/ad/graphics/s9_mag_apl_1966_pg06.gif

If you had a payroll with factory overhead to meet on a weekly basis at a time when your market research gurus told you the Ham business was headed toward geezerdom while the CB biz was wide open for near limitless expansion... What would you do? Sit back and hope that CW McCall's next song was about working a CW contest on 40 Meters?

BTW: With 23 channel TX and RX, possibly all crystal controlled, a fully rigged CB (in the early days) could require 46 crystals. So, is it any surprise these folks had a radio for you with more rocks than Fred Flintstone's garden? http://www.cbtricks.com/radios/international_crystal/750h_750hb/ad/graphics/s9_mag_aug_1964_cover02.gif
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W3LK
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Posts: 5639




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« Reply #7 on: March 01, 2011, 03:07:41 PM »

And don't forget Motorola's short-lived entry into the CB field, the MOCAT. It was probably the best designed and constructed CB radio ever made, but alas, it was too expensive and came towards the end of the CB craze.

Darn good little radio.

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