| Author |
Message |
    
Xmeter
| | Posted on Tuesday, December 30, 2003 - 8:40 pm: | 
|
I have a Palomar 350z base amp that needs both relays replaced. My problem is that someone removed both of the plastic covers off of the relays that have the part numbers on them. If anyone out here that has one of these things that could give me the part numbers off of theirs I would for ever be in your debt. Both relays are the same and they are Potter Brumfields. Thanks and have a Happy New Year. |
Stitches
| | Posted on Tuesday, December 30, 2003 - 11:24 pm: |
|
Xmeter:
The ones in my 350Z are both "AMF" Potter-Brumfields # R10-E3604-2
185 Ohms
12 VDC
7736
Relay 1= Ant. Changeover
Relay 2= Rec. Pre Amp
With the Amp turned upside down and Bottom cover off, Knobs faceing you, on your left hand side will be the board that holds the relays. Relay 1 is the one behind the Hi/Low switch.
Relay 2 is the one behind the On/Off
power switch.
By the Way, Have you had any problems with your amp over heating when it's not being keyed up? Mine did the other day and it was in "Standby" mode, Pre amp switch turned "Off" and it got hotter than heck and blew the fuse! Would you or anyone else know what I should do to fix this problem? or does this amp need a mod of some kind to prevet this?
|
2600
| | Posted on Tuesday, December 30, 2003 - 11:57 pm: |
|
Hi Xmeter,
Those relays look perfectly mundane from the top, but when you look at the arrangment of the pins underneath, it becomes clear that they are totally unique, and unlike ALL the standard relays that size that you can buy.
The original number that was printed on the now-missing plastic dust covers is "R10-E3604", a Potter and Brumfield "house" number. Don't worry about "owing" me one for that number. It won't do you much good, by itself. They are, in effect, a custom part designed specifically to use in linear amplifiers. It contains a small metal shield inside that prevents stray RF power from "leaking" from the contacts carrying the power onto the windings of the coil. A great engineering idea, but a nightmare for someone who wants to repair the thing.
Drilling new holes in the circuit board to accept a more standard "R10-type" relay just isn't practical. There isn't enough room to drill new holes and improvise all the connections to their new locations. There isn't enough vertical clearance to install a relay socket.
RF Parts used to list that one until about ten or fifteen years ago. They were the ONLY source on the planet until they finally ran out of them for good.
Even if you found the relay, the nightmare would just be starting. The only way to get any service out of a 350Z is to convert the keying circuit to turn the tubes off when it is not keyed. The original design leaves all six of them pulling current, and throwing about 25 watts of heat apiece just sitting there on standby, waiting for you to key the radio. That's bad enough, but the two trimpots underneath that set the "bias" voltage to control that current draw are failure-prone. When they fail, the tubes attempt to draw all the current the power supply can deliver. This will cause the tubes to overheat and "cherry up", glowing red from the part of the tube that should stay dark. Glass melts, cracks and things go "POP". The 350Z may not qualify for the all-time Mushroom-Cloud Award, but it sure is in the running for it.
As if I didn't have enough bad news about this model, you need a good supply of GOOD tubes to make one of these run at all. Yeah, everybody says the tubes are "good". The amplifier pushes them to (or past) the limits of the ratings. A tube that isn't completely up to snuff will blow out one of the small resistors under each tube socket. Add to that the need for all four of the final tubes to match each other and share the load equally. If one of the four is stronger than the other three, it will "hog" the load, and throw more than its share of the heat and fail.
The two driver tubes have to match each other. If they don't split the load 50-50, one of them will overheat and pop. Finding a pair of tubes that will match this way is easier than finding a set of four.
If ANY of the electrolytic capacitors are original, you should expect them to be defective, or at least ready to fail very soon. They just aren't meant to last more than 15 to 20 years, max.
The only solution I know that works is to completely rip out the two circuit boards with the keying/preamp circuits and relays. A new 3-section 15-Amp relay goes in their place, along with a new keying circuit. Got some pics here somewhere, but never have posted them on the web. Even with the major expense of going that route, there won't be a preamp.
Problem is, that shop won't accept work shipped in, only carried in their door. And they insist the customer supply enough tubes to make one set of four and one pair. Doesn't do you much good.
Mind you, this isn't a complete list of the shortcomings built into the Palomar 350Z. Just the highlights.
Sorry to rain on your parade, but you might as well be planning a "showroom" restoration of a 1963 Plymouth Valiant. There are more cost-effective ways to drive to work every day. Lots of 'em.
Amplifiers have never been cheaper. Never. What you will spend in dollars per Watt to breathe life back into a 350Z is a LOT more than the "Watts per dollar" that a new one offers, whether tube or solid-state.
73 |
Stitches
| | Posted on Wednesday, December 31, 2003 - 8:42 am: |
|
Well......from reading this, it seems that I'm an owner of a Palomar "Door-Stop" now. |
Scrapiron63
| | Posted on Wednesday, December 31, 2003 - 11:10 am: |
|
Hey Stitches, it oughta hold a pretty good door. lol. You might get some pretty good service out of it, if you don't push it very hard. I never understood why Palomar built something like the 350z after all the good amps they built. I bought a new 350z back in the 1970s, thought it would be perfect, could run it with my CB radios and my Yaesu 101, but that was a mistake. Of course I had the DRO (dumb radio operator)syndrome back then, ran everying wide open, and the tubes didn't last long. I bought a new set of tubes, but didn't read the book about the need to neutralize them, keyed it up, they went into self isolation, wouldn't unkey, and flatten them before I thought to shut it down. I then learned how to run the thing, and had pretty good success, but the big old resistor up under the front of the amp burned a spot on my desk before I jacked it up a little higher, man that thing would get hot. I got rid of it pretty soon after that, went back to the much more reliable D&A and Maco equipment. But you know later, probably in the early 1980s, I bought a couple of old 350z's at a sale, both were down, and they were dirt cheap. I took them to a good tech that was in business here at that time, he did some work on them, don't really know what was involved, but made them pretty good old amps. They wouldn't load up near as much, maybe 200-250 watts, but the swing was great. I sold them later, but kept up with'em for a good while, and they held up ok. Of course that was almost 20 years ago, the old 350z's are getting very old now. scrapiron |
Stitches
| | Posted on Wednesday, December 31, 2003 - 12:43 pm: |
|
Neutralize the tubes? explaine this to me ok? Does this have to be done with old tube type cb/ham radios too?
When I looked at the relays for the numbers for Xmeter I saw some things that I didn't like. The two resistors next to the two large Axial Caps are a very dark brown under them, and where the transformer is, the bottom cover plate is corroded there.
Looks like it's been like that for some time now. I guess there isn't much hope for this ol'boat anchor now. |
Xmeter
| | Posted on Wednesday, December 31, 2003 - 2:22 pm: |
|
Thanks for all the help. This forum is just full of knowledgeable people. I learn something new every time I log on. |
Scrapiron63
| | Posted on Wednesday, December 31, 2003 - 5:43 pm: |
|
Most of the old tube type ham radios had a process for neutralizing the tubes, and lots of amplifiers. There are some voltage adjustments that need to be checked/set, but you need the operator's manual. I've changed tubes in lots of amps and radios, but that one 350z is the first one that went crazy on me, those 6lf6's really got to glowing pretty red. It taught me a lesson though, I've watched out for that in the preceeding 25+ years. |
Stitches
| | Posted on Wednesday, December 31, 2003 - 6:09 pm: |
|
Sounds like there isn't much "gray" area with the 350Z, this Ol'rig worked so well for the 13 years that I've had it, then it's life seemed to change all of a sudden on me. I really liked this Amp. Maybe it's like me, needs some new parts and a little TLC to get it up again. |
Bigbob
| | Posted on Wednesday, December 31, 2003 - 6:42 pm: |
|
Hey Scrap,your username pretty much somes it up for the ol' 350z,collect enough of 'em you might be able to make some money at recycle,lol.Bigbob |
Stitches
| | Posted on Wednesday, December 31, 2003 - 7:04 pm: |
|
Hey Bigbob:
I felt that! You just dottrd my eye didn't you! |
2600
| | Posted on Saturday, January 03, 2004 - 4:53 am: |
|
Every time I spot a 350Z on a table at a flea market, I'll ask "What kind of fire extinguisher comes with that?" They almost never laugh.
73 |
Stitches
| | Posted on Saturday, January 03, 2004 - 1:48 pm: |
|
Oh! now THAT was a good one 2600. I'll have to remember that if I'm lucky enough to spot someone trying to sell one to some poor ol' sap like me lol. |
|
