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Post by doctor on Jul 11, 2008 16:47:51 GMT -5
I ran into a robyn 520 at a cb shop looked like it came out of the box from the factory, it had uppers and lowers in it, the chap wanted $130 for it, it had am/ssb, anyone know anything about these drift on ssb? or other problems DOCTOR/OT795  |
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Post by hillbilly1987 on Jul 11, 2008 18:34:04 GMT -5
wow i bet that puppy is old and sry doctor i wouldnt know anything about them
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Post by 2600 on Jul 31, 2008 0:18:23 GMT -5
It's a good old AM/SSB radio. "Old", as in 1977 or '78.
If you decide to turn up the AM modulation, there is a small (usually blue) 2.2 uf capacitor in it that routinely shorts out when the AM audio level gets cranked. What makes it fail is the voltage rating. 25 Volts is not enough. Replacing it with one rated at 50 Volts takes care of the problem. Don't think I have a picture of this one handy. If the AM modulation stays turned down, that part may last a while.
The uPD858 PLL chip in that radio can be modded for more channels than the rest of the radio can cover. For the most part, these 'extra' frequencies will be scrambled out of their normal order. Takes a printed list and/or a counter display to keep track of them.
If the radio's mileage is really low, you could get a year or maybe two out of it before the first real breakdown. Maybe. Some parts are not meant to last this long, and will 'remember' how old they are in a year or three after hiding in a closet for 29-plus years. Odds are that one or more rotary controls will be 'scratchy' and benefit from a squirt of "control"-type cleaner, one containing a light lubricant. A "non-residue" type 'contact' cleaner will remove the original lubricant film from the contact surfaces.
The relay is obsolete and made from a substance called "unobtainium". If the contacts get noisy, a strip of paper moistened with CONTACT cleaner may clean it up. Any kind of abrasive will ruin the electroplated contact surfaces inside it.
Seems to me that the mike socket is wired differently from the normal Cobra/Galaxy pattern. Moving the wires inside the mike socket to match a Cobra mike makes life easier.
The lower the mileage, the more service you'll probably get from it.
73
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Post by zman on Oct 21, 2008 18:29:33 GMT -5
I have had a few 520s over the years and NEVER had any issues you speak of. Good old radio and built like a tank.
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Post by 2600 on Oct 28, 2008 15:21:35 GMT -5
With all due respect to your personal experience, I mostly see them when they break.
The ones that don't break seldom come to visit.
73
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Post by gator7 on Oct 30, 2008 5:40:43 GMT -5
LOL, Well said.
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Post by ak3383 on Sept 12, 2009 23:05:19 GMT -5
Old thread I know but was the radio shop you saw the Robyn at located about 20-miles west of Indy???
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Post by zman on Oct 18, 2009 21:48:57 GMT -5
Good old rig. However the audio chip is pretty scarce. If the audio is cranked up enough that radio will TALK on AM!
All the ones ive had worked great with no issues.
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Post by cbrown on Oct 19, 2009 13:54:37 GMT -5
Seems to me that the mike socket is wired differently from the normal Cobra/Galaxy pattern. Moving the wires inside the mike socket to match a Cobra mike makes life easier. Ya, the shield and audio wires are reversed from a Cobra type radio. I never recommend changing the wiring in a radio to match a microphone. I prefer wiring the mic to the radio, or making an adapter. |
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Post by zman on Nov 29, 2009 19:26:15 GMT -5
i never could understand why people do that to a radio. Or they get inside the mic and rewire the insides of the mic. Ugh!
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Post by cbrown on Nov 30, 2009 17:08:15 GMT -5
I wouldn't mind so much if they'd put a note on the radio to at least let the next owner know. Don't get me started on the microphone wiring horror stories, either.  The worst one I ever saw was a Astatic TUG-8 base where they ripped the wiring out of the base of the stand to make it work with the radio instead of rewiring the microphone plug. No tape, no solder, no wire nuts - just wires twisted together with random bits of zip cord used where the wires weren't long enough or cut back. It annoyed me so much I redid the entire thing (to factory specs). I swore I'd never deal with a mess like that again. |
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Post by zman on Jan 28, 2010 15:58:48 GMT -5
LOL i had a Turner plus 3 once that has completely changed around inside. I simply wanted to wire it to a Drake Tr-4 i had and i almost threw the mic out of the shack window. I FINALLY got it wired to factory specs and it worked like a champ on that old Tr-4.
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Post by zman on Jan 28, 2010 16:01:04 GMT -5
As a sidenote, i know a local that used to run a Robyn SB 520D that he got new in 1977 and he used it for years until he got a "big ugly black box radio"... he never once had a problem with it and it was modded to the max.
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Post by cbrown on Feb 1, 2010 9:46:20 GMT -5
LOL i had a Turner plus 3 once that has completely changed around inside. I simply wanted to wire it to a Drake Tr-4 i had and i almost threw the mic out of the shack window. I FINALLY got it wired to factory specs and it worked like a champ on that old Tr-4. Microphones like that help explain my hair loss... ;D Glad you got it back into shape. |
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Post by zman on Feb 11, 2010 22:00:04 GMT -5
I still have some hair left, LOL.
anywhoooo, even with all the negatives about the parts availability for the Robyn there are plenty of them around that if one goes down there are 20,000 more to take its place!! So parts should be around for a long time to come for this old warhorse.
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Post by missourimustang on May 18, 2010 16:12:00 GMT -5
I have a 520D.I had 2 others several years ago.this one makes No.3.Most of them Ive seen had a black front, this one is woodgrain, the first one I ever seen.But it needs worked on.The former owner blew the finals when plugging the wrong mic up to it.Then the power supply has issuses. It will only power up when connected to DC power, a 12V power supply.Other than that ,its a great base unit.I'll get it repaired sometime.Its not eating anything in the meantime.A Robyn 520D is a good buy.Its a shame it didnt have a mic gain control...
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Post by zman on May 20, 2010 20:53:33 GMT -5
When the 520D is tuned up properly by a competent tech, it DOESNT need a power mic! :-)
I have a woodgrain that needed the final and driver replaced and it actually works better with just the plain jane handmic. than it does with a power mic. Great old radios and i have always loved the older 858 PLL rigs.
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Post by skipwave62 on Jun 23, 2010 4:27:38 GMT -5
Too funny 2600 ..That's like a roof on a house I had..when it rained it leaked and it was to wet to fix it!!! but when it was dry out it did'nt leak so need to fix it....Imagine that!
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Post by zman on Jul 29, 2010 21:18:00 GMT -5
Ive noticed most of the 520s seem to have a funny little "chirp" when keyed on SSB.
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The worst one I ever saw was a Astatic TUG-8 base where they ripped the wiring out of the base of the stand to make it work with the radio instead of rewiring the microphone plug. No tape, no solder, no wire nuts - just wires twisted together with random bits of zip cord used where the wires weren't long enough or cut back.