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 Post subject: Opinions please-Should I even bother with this?
PostPosted: Sep Mon 11, 2017 7:07 am 
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Yesterday, I picked this up for a very low price:

Attachment:
rIMG_0603.JPG
rIMG_0603.JPG [ 88.25 KiB | Viewed 686 times ]


This is a Wavetek 3000-200 signal generator.

Of course it doesn't work. No output, and no output meter indication.

I found a service manual on-line. There are three power supply voltages-7 VDC, +18 VDC and -18 VDC. the 7 volt supply was normal but the 18 and -18 volt supplies were shut down, with almost no voltage. I pulled all the internal modules and the voltages went back up to normal.

I found bad tantalum capacitors in several of the modules. These were shorted, causing the 18 volt supplies to choke. replacing them brought the 18 volt supplies back for a couple of minutes, and then they dropped to somewhere between 10 and 12 volts, and the no-lock LEDs on the modules began lighting dimly. There is no signal at the RF output but I am now getting an indication of output on the meter that can be varied with the vernier control. I am assuming that this is being caused by more of the tantalums breaking down, since I didn't replace them all.

In my research on this generator, I am reading lots of things that are not very complementary about either reliability nor ease of service. I could go through all the modules and replace the problem capacitors, but I am wondering if it is worth it to go any further if it is still going to be troublesome to get / keep running.

When I was a bench tech in the 1980s I used a couple of Wavetek generators (not this model) regularly and didn't have any problems with them then, so I took a chance on this one and don't have much money in it in any case. Your thoughts?


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 Post subject: Re: Opinions please-Should I even bother with this?
PostPosted: Sep Mon 11, 2017 7:16 am 
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Thumbwheel switches as the only way to set frequency gets REALLY old REALLY fast.

These were meant for an industrial test set-up where the freq didn't change.

- Leigh

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 Post subject: Re: Opinions please-Should I even bother with this?
PostPosted: Sep Mon 11, 2017 9:10 am 
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Don't you just love those tantalum capacitors, you might as well replace all of them if you want it to work.

Dave


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 Post subject: Re: Opinions please-Should I even bother with this?
PostPosted: Sep Mon 11, 2017 9:34 am 
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Thumb wheel switches on stuff I have worked on were BCD needing a separate layer
of digital grief, especially if they use hard to find RTL chips

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 Post subject: Re: Opinions please-Should I even bother with this?
PostPosted: Sep Mon 11, 2017 10:43 am 
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For most stuff, I stumble through with my Precision E200C and Eico 369. If I were to invest in another generator, it would have to have sweep.

That Wavetek seems to have a nice attenuator

Trouble-shooting modules with ICs?-------yuck!!

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 Post subject: Re: Opinions please-Should I even bother with this?
PostPosted: Sep Mon 11, 2017 11:47 am 
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Quote:
When I was a bench tech in the 1980s I used a couple of Wavetek generators (not this model) regularly and didn't have any problems with them then...
I'd say so long as you don't have too put much time or money in it, and I realize it depends on your perspective, I'd keep going.

Wavetek had a lot of innovative ideas in the day, but their engineering/implementation left a lot to be desired. They tended to gloss over design areas that needed more attention to detail. Maybe price point pressures, who knows?

I tried one of their function generators once upon a time, and was pretty disappointed in its performance.

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 Post subject: Re: Opinions please-Should I even bother with this?
PostPosted: Sep Mon 11, 2017 3:02 pm 
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I had three of those at one time, and the happiest day of my life is when I was able to all three working and sold off to new owners. I paid as much for a good manual as I did for one of the generators.

As others noted, the power supply rails have tantalum caps. Most are hidden inside of the modules. If those caps haven't failed, they will. The modules are interesting--a lot of point to point hand wiring and discrete components.

Troubleshooting is made somewhat easier by the lock LED's located on the modules that have phase locked loops. The output from those generators is produced by numerous phase locked loops chasing each other's tails in a circle. The phase noise performance is horrendous. They made excellent broad noise generators when tuned off frequency. The thumb wheels are no worse than cranking a HP-8640B, but that also gets old fast.

Pete

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 Post subject: Re: Opinions please-Should I even bother with this?
PostPosted: Sep Mon 11, 2017 3:22 pm 
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It looks like the modulation deviation goes high enough for broadcast FM, if my guess about the function of the FM x 10 switch position is correct. Might make a nice transmitter for the pre-war FM band.

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 Post subject: Re: Opinions please-Should I even bother with this?
PostPosted: Sep Tue 12, 2017 4:44 am 
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Peter Bertini wrote:
....... As others noted, the power supply rails have tantalum caps. Most are hidden inside of the modules. If those caps haven't failed, they will. .........Pete


Are they jelly bean tantalums or are the voltage ratings close to the rail voltages?

RRM


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 Post subject: Re: Opinions please-Should I even bother with this?
PostPosted: Sep Tue 12, 2017 1:06 pm 
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If it is just a matter of changing some bad capacitors, I'd go ahead and fix it.

Many of the elaborate signal generators we talk about here, the HPs, GRs, Boontons, and others, were never meant for fixing consumer radios. The fact that we can use them for such purposes today is due to the rapid pace of technological change, and the fact that most electronics design and development is now in east Asia and they have no need for our old test equipment. Almost as if somebody was to get a surplus Mars Rover from NASA and use it for a golf cart, but that's the way it goes.

So the Wavetek is not an HP, GR, or Boonton. Big deal; it still beats an Eico, Heathkit, or PACO entry level signal generator by a long shot.

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 Post subject: Re: Opinions please-Should I even bother with this?
PostPosted: Sep Tue 12, 2017 1:59 pm 
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Primitiveradiogod wrote:
...
This is a Wavetek 3000-200 signal generator.
...
I found a service manual on-line.
...

Would you care to share the link?

Peter


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 Post subject: Re: Opinions please-Should I even bother with this?
PostPosted: Sep Tue 12, 2017 2:16 pm 
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Retired Radio Man wrote:
Peter Bertini wrote:
....... As others noted, the power supply rails have tantalum caps. Most are hidden inside of the modules. If those caps haven't failed, they will. .........Pete


Are they jelly bean tantalums or are the voltage ratings close to the rail voltages?

RRM



It has been several years since I've owned them. I could look in the manuals, which I kept, if
you are curious. I am pretty sure they used the jelly bean style.

The biggest problem with these is keeping them going. Out of three, one always would fail--
either due to a lock problem, or a newly failed cap. Repairing or aligning them is no trivial
matter.

You need a good UHF counter, and even a spectrum analyzer comes in handy.

Pete

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 Post subject: Re: Opinions please-Should I even bother with this?
PostPosted: Sep Tue 12, 2017 4:00 pm 
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orbanp wrote:
Primitiveradiogod wrote:
...
This is a Wavetek 3000-200 signal generator.
...
I found a service manual on-line.
...

Would you care to share the link?

Peter


K04BB.com has it - Wavetek 3000 manual.

Edit: Only 70% of the modules in the two (3000 vs 3000-200) have commonality.

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 Post subject: Re: Opinions please-Should I even bother with this?
PostPosted: Sep Tue 12, 2017 7:42 pm 
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Thanks!

Peter


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 Post subject: Re: Opinions please-Should I even bother with this?
PostPosted: Sep Tue 12, 2017 7:57 pm 
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Peter Bertini wrote:
The biggest problem with these is keeping them going.
Several decades ago I worked for a highly-respected cal lab that was the warranty service station for Wavetek.

Those used a lot of proprietary parts, and Wavetek would not provide those even to us.
Basically we would troubleshoot. If it was not a common cap or resistor problem, we had to return it to them.

As a personal opinion... I wouldn't take one of their products if I was paid to do so.
When they work, they work quite well. When they don't, they make good door stops.

-Leigh

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 Post subject: Re: Opinions please-Should I even bother with this?
PostPosted: Sep Tue 12, 2017 8:10 pm 
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I've a few of their function generators which were quite reliable. But their signal generators and sweepers were horrible.

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 Post subject: Re: Opinions please-Should I even bother with this?
PostPosted: Sep Tue 12, 2017 9:19 pm 
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Quote:
It has been several years since I've owned them. I could look in the manuals, which I kept, if
you are curious. I am pretty sure they used the jelly bean style.


Not sure if this is true throughout the production run, but mine has the bullet-shaped tantalums. I am using the jelly beans as replacements. My theory as to why these things are so prone to failure in this generator is that they used 25 volt tantalums. The power supply voltage prior to hitting the regulators is about 30 volts. It is considered to be good engineering practice to rate your components somewhat higher than any voltage the unit is likely to see. The supply is probably spiking beyond 25 volts for a brief moment at every turn-on, and enough power-ups over time will kill the caps.

Quote:
As a personal opinion... I wouldn't take one of their products if I was paid to do so.
When they work, they work quite well. When they don't, they make good door stops.


Your opinion is shared by many on the internet, hence my original question. I will continue to work on this thing to see if I can get it to come up, but I wouldn't be surprised if it winds up being a shelf queen.

In addition to caps, it is rumored that there are op-amps in some of the modules that are being run to the very bleeding edge of their maximums and will often fail. What fun!


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 Post subject: Re: Opinions please-Should I even bother with this?
PostPosted: Sep Thu 14, 2017 1:36 am 
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The reason I asked about jelly bean tantalums is my "roadside" Heathkit scope was full of them and they went out one at a time until I got rid of them. I've forgotten the ratings but I think they were 25 volt caps on 15 volt rails. The regulators are discrete designs and I believe they sometimes overshoot enough to kill the tantalums.

We used tantalums at work but they were all mil spec and greatly de-rated. I'd use at least a 50 volt cap for a 25 volt rail and no jelly beans for me.

RRM


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 Post subject: Re: Opinions please-Should I even bother with this?
PostPosted: Sep Sat 16, 2017 4:25 am 
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I replaced all the remaining tantalums on the power supply rails whether they tested OK or not. That involved opening all the modules and confirming where they were.

After that, I turned this Wavetek on. This time, the +18V and -18V rails actually came up and stayed at 18 volts. I connected a scope to the output and got this:

Attachment:
rIMG_0609.JPG
rIMG_0609.JPG [ 98.08 KiB | Viewed 148 times ]


That's a fairly clean 10 Mhz (or so) sine wave, but that is where this party ends.

The no-lock LEDs on modules M32 and M34 are on. Setting the generator to anything below 10 MHz results in horrible phase noise that is clearly visible on the scope. I tried hooking the output to a counter and to a radio and the frequency shown on my counter is somewhat higher than the set frequency and varies quite a bit from moment to moment. On the radio, even above 10 MHz the spurious noise levels make the generator pretty useless in its present state .

Wiggling some of the fully anchored modules results in a waveform of varying quality and frequency. The modules themselves look like they were assembled in someone's garage using grade B tools.

The no-lock LED on the M34 module will go off if the frequency is set to 30 MHz or 70 MHz, and will lock and unlock at every other setting of the 100 MHz thumbwheel switch. (in other words, half the 100 MHz settings illuminate the LED and half don't)

Reading the manual suggests that the phase locked loop problem is likely caused by a fault in either the M30, M32, or M34 modules. This thing apparently takes harmonics from a 40 MHz clock and amplifies them to generate a 1200 MHz and 1440 MHz reference frequency in the M30 module. I have confirmed with reasonable certainty that the 40 MHz clock is working, since the divided-down 1 MHz TTL clock is good, but I have no way of confirming if the 1200 and 1440 MHz harmonically generated outputs are good. I don't have a scope or a counter that goes that high.

While it is possible that resolving the PLL problems might make most of the other problems go away, the mechanical stability issues are, to me, a real deal breaker. The whole point of having a synthesized dial-a-frequency-generator like this is the lab-grade stability and ease of use. Take those things away, and you might as well use a 1950s-era EICO generator.

My radio club has one of these generators, or something very similar. I'm pretty positive that the problem modules are identical. I might try doing a module swap to see if I can isolate the issues to a specific module. Aside from possibly trying that, I am done with this thing. It has the all makings of a turd.


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 Post subject: Re: Opinions please-Should I even bother with this?
PostPosted: Sep Sat 16, 2017 12:44 pm 
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Before you condemn the modules, I'd concentrate on cleaning anything with a socket. Clean clean clean, properly (many threads on the forum on this).


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