James,
I wasn't sure on the plate voltage I listed so I checked it and it should be
4000 Vdc maximum. So say 3500 to 4000 Vdc.
Will
*********** REPLY SEPARATOR ***********
On 5/21/05 at 2:46 PM JAMES SMITH wrote:
>(Redirected by "Will Matney" <craxd1@ezwv.com>)
>James, see below;
>
>*********** BEGIN REDIRECTED MESSAGE ***********
>
>REGARDING A NEWLY ACQUIRED 6 METER
>AMP THAT COVERS 1.8 TO 53 MHZ BUT IS NOT WORKING TO IT'S FULLEST
>EXTENT. I HAVE SOME KNOWLEDGE BUT AM STILL A AMATUER. IT WAS TAKEN TO A
>HAM REPAIR SHOP AND THE TECH WAS ABLE TO TELL ME THAT THE PROBLEM WAS
>PROBABLY IN THE TANK PORTION OF THIS AMPLIFIER BUT COULDN'T TELL WHAT
>EXACTLY WAS WRONG BECAUSE OF THE LACK OF SCHEMATICS.
>
>They needed schematics for a tank circuit?
>
> IT IS A VERY SIMPLE AMPLIFIER USING 2 3-500Z'S. IT ONLY PUTS OUT 400
>WATTS PEP AND FROM WHAT OTHERS TELL ME IT SHOULD PRODUCE 1200-1500 WATTS
>PEP WITH APPROXIMATELY 100-150 WATTS OF DRIVE.
>
>That's about right. First, what is the SWR between the transceiver and the
>amp? Next, on each band, where does the tune and load capacitors set at,
>about mid way or fully meshed when tuned?
>
>IM NOT SURE IF IT IS A NORMAL CONDITION BUT IT ARC'S ACROSS THE TUNING
>CAPS WHEN UNKEYED LIKE STORED VOLTAGE.
>
>No that's not normal. I would check the parasitic supressors on the top of
>each tube. They should be something like two 100 ohm 2 watts in parallel
>with a coil.
>
> I CAN'T SEE THE COLORS OR THE RESISTORS THAT GO TO THE TOP OF THE TUBES I
>WAS JUST GOING TO START REPLACING THINGS BUT FIGURED THAT IF SOMEONE MIGHT
>BE ABLE TO LEAD ME IN THE RIGHT DIRECTION IT WOULD MAKE THINGS A LOT LESS
>TIME CONSUMING.
>
>If there's 2 resistors on each tube, most likely they're 100 ohm 2 watt.
>If only one, a possibility could be 47 ohm 2 watt. That would be kinda
>undersized though for two 3-500Z's.
>
>THE TECH DID TEST THE TUBE'S THEY TESTED AT 90-95%. ALTHOUGH I DID HAVE
>ANOTHER BRAND NEW SET I STUCK IN JUST IN CASE AND STILL THE SAME. I DO
>PLAN ON RE-WIRING IT AS SOON AS I CAN BECAUSE SOME OF THE SOLDER JOINTS
>LOOKS PRETTY BAD. IT HAS TWO TRANSFORMERS AND IM THINKING THAT ITS A GOOD
>POSSIBILITY THAT ONE IS GOING BAD AND TH
> AT VOLTAGE SUPPLY IS AN ISSUE.
>
>What is the plate voltage? Does the amp have a voltmeter to check it?
>Also, if it does, can you read the plate current? If a transformer were
>going bad it would either be shorted to where it would blow a fuse pretty
>quick or run really hot and smoke plus hum loudly. If one were open, it
>wouldn't have any voltage coming out of it at all. I imagine one is the
>plate transformer, and the other is for the filaments. I don't think you
>have anything wrong in the transformer department, maybe in the rectfier
>circuit or filters. If the tubes light up, then the filament transformer
>is okay. If you have high voltage at the right amount, then that
>transformer is okay. Without either, you wouldn't have even see 400 watts.
>
>ONE SUPPLIESW VOLTAGE TO THE TOP OF THE TUBES AND THE OTHER SUPPLIES
>VOLTAGE TO THE BOTTOM OF THE TUBES. THREE OF THE TUBES ARE SHORTED TO
>CHASSIS GROUND. IT ALSO HAS A BANDCOIL AND NOT A SWITCH TO GO FROM 6, 10,
>12, 15, 20, 40, 80 METERS SO YOU CAN REALLY
>FINE TUNE. IF YOU COULD HELP I WOULD BE VERY GREATFUL. I ALSO UNDERSTAND
>THAT THEY ARE VERY DANGEROUS TO WORK ON IF NOT EXPERIENCED. I KNOW
>BETTER THAN TO STICK MY FINGERS IN UNLESS IT IS DISCHARGED. IF YOU COULD
>GIVE ME A REFERENCE VOLTAGE AT A COUPLE OF PLACES I COULD CHECK THE
>VOLTAGES AND REFER BACK TO YOU FOR FURTHER ASSISTANCE.
>
>3-500Z's run anywhere from +2500 to +3000 Vdc, and the filaments are 5 Vac
>if I recall.
>
>OR I COULD TAKE
>PICTURES AND POST THEM WITH AN E-MAIL SO YOU COULD SEE THE DESIGN. OR IF
>YOU CAN'T HELP ME MAYBE YOU CAN REFER ME TO A REPAIR SHOP THAT CAN
>DEFINATELY FIX THE THING. DUE TO IT'S WEIGHT I'D RATHER NOT SHIP IT
>THOUGH.
>ANY HELP WOULD BE GREATLY APPRECIATED. KG6NLB@YAHOO.COM JAMES SMITH @
>209-329-3826 YOU MAY CALL IF IT WILL BE EASIER OVER THE PHONE ALSO.
>
>
>First thing I'd do is go over any solder joint that looks to be cold
>soldered. Clean the relay contacts with a contact burnisher. GC
>Electronics makes these little flexible files. You may be able to use a
>piece of really fine sand paper like 400 grit. A few passes on each
>contact surface is all it takes. If the SWR is high between the
>transceiver and the amp, that will kill the power too..
>
>
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>*********** END REDIRECTED MESSAGE ***********
>
>Best,
>
>Will
>
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