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 Post subject: Wavetek signal generators
PostPosted: Jun Wed 26, 2013 12:51 pm 
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Location: Canandaigua, NY
I love Wavetek signal/function generators, but every one I've ever used seemed to need repair at some point. Last night I went to use my 185 for a project needing sweep and the sweep didn't work. This is mostly a Post-it note for the various things that seem to go wrong on a regular basis:

1) Bad electrolytics. These units are old enough that bad caps are common. Mine has had several go out of spec, and a couple more with green corrosion on the positive leads. Change as necessary, or change 'em all.

2) Bad IC sockets. I think some of the sockets used in these were just cheap. Re-seating ICs doesn't always do the trick and I had to carefully remove a socket and replace it with something better. Tinned double leaf are actually the most reliable, not gold plated machined contacts as some would believe, though those will work fine too.

3) Cracked traces. Operation of some controls, particularly the sweep time pot on the 185 will crack the traces/solder joints over time. Inspect under magnification and re-solder and reinforce as needed.

4) Bad wire crimps on Molex-type connectors. Over time some of these oxidize and become intermittent, even though they look fine. Carefully depress the contact lock, pull the contact out and solder the crimp area. It will take a hotter than normal iron and good solder with RMA flux to wet the contact and wire. Don't fill the contact so it can't spring properly. This was the latest problem on my sweep PCB.

5) Though heat sinked, the output stages will burn and fail if abused. Don't short the outputs and it's probably a good idea not to run at high levels into 50 ohm loads for long periods of time.

No doubt specific units will be prone to specific problems, but that's my list for the 5 MHz 185! I also have a 166 (I think) 50 MHz unit that has suffered from similar problems.


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 Post subject: Re: Wavetek signal generators
PostPosted: Jun Wed 26, 2013 5:26 pm 
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Location: Littleton, MA
I have a 2U rack-mount beast of a Wavetek anchoring one of my racks in the basement lab, awaiting restoration. I don't recall the model number at the moment and can't find anything on it via Google. It's a solid-state function generator (I don't recall if it's all discrete transistors or if it's full of µA709's) that is frequency-locked to an RTL frequency synthesizer. You set the frequency via a set of front-panel rotary switches for the digits. Should be loads of fun to get working.

I also have an HP 202A vacuum-tube low-frequency function generator holding down the other end of the pile of junk in the lab.
Image
(Photo from HPmemory.org)

By the way, I love your site; it's been an inspiration to me for a while now as I start to learn about metrology and collect some of these old instruments. Just scored a GR 716-C last month from the MIT lab clean-out; your 716-C notes will come in handy.

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 Post subject: Re: Wavetek signal generators
PostPosted: Jun Fri 28, 2013 4:51 am 
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I've said this before and I'll say it here, again: Wavetek should stick to making RF signal analysis meters- period. Those were some very well designed and quality assembled items, but when they branched out to include other stuff, they often fell short. There aren't many companies that can produce reliable, quality products across a broad spectrum. Yamaha, HP, Honda, Sony are four brands that have been very successful at it.

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 Post subject: Re: Wavetek signal generators
PostPosted: Jun Fri 28, 2013 5:20 am 
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I've owned a few WaveTek function generators, and they were fairly decent...

on the other hand, I had three of their synthesized RF generators, and they were among the worst test gear I have owned for reliability. And the phase noise was beyond horrendous.

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 Post subject: Re: Wavetek signal generators
PostPosted: Jun Fri 28, 2013 7:35 am 
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Used a Wavetek function generator, at my first electronics job. Stayed there for 10 years, and the thing never showed a problem. In school, in my RF lab we had a few RF generators. They where temperamental. I just assumed it was due to being old and much abused by the students. Plus maintained by stockroom techs who may not have possessed opposable thumbs.

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 Post subject: Re: Wavetek signal generators
PostPosted: Sep Sun 28, 2014 10:08 pm 
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Location: Canandaigua, NY
Thread back from the dead- I just opened up the 185 again to find a couple more cracked solder joints that I must have missed the first time. There's no reason they should have cracked, as they aren't stressed in use. I wonder if there's some other mechanism that cracks solder joints, some inherent weakness from original manufacture of the boards, but I can't imagine what it would be. Also replaced a couple caps that were at the low end of spec. I use this thing almost every day and it's still my favorite sig gen. Modern is nice, but for daily use I want knobs, not keypads!


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 Post subject: Re: Wavetek signal generators
PostPosted: Sep Mon 29, 2014 11:49 am 
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Collins bought a few Wavetek function generators in the mid 70s. They were scrapped, after about 6 months of repeated repairs. They had some innovative ideas, but lousy design and implementation.

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 Post subject: Re: Wavetek signal generators
PostPosted: Sep Mon 29, 2014 3:26 pm 
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Location: Canandaigua, NY
Yes, Collins has pretty high standards and the Weveteks certainly weren't built to that level. OTOH, they didn't sell for that much new, compared to HP or others.

edit- I also think the Wavetek circuit designers were pretty good. Getting their current source to sweep properly over the range they achieved couldn't have been easy. Well, at least I doubt I could have done it. Putting the units in plastic Pac-Tec cases probably dictated some less than robust mechanical choices that led to electrical reliability issues.


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 Post subject: Re: Wavetek signal generators
PostPosted: Sep Mon 29, 2014 9:26 pm 
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I have one of the Wavetek 148A function generators. Nada-zero-zip ventilation for anything inside the plastic case that serves as the backbone for the whole thing, and after a few hours of use the top of the case gets awful toasty to the touch. I'm sure this contributes to a lot of the failures with these style Waveteks. This is where I don't mind listening to the HP 3325A FG's cooling fan, because I don't think a single repair has ever been done to the HP since it was made in '77.

-Mark-


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 Post subject: Re: Wavetek signal generators
PostPosted: Sep Mon 29, 2014 9:41 pm 
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Interesting, the 148A looks like a very useful piece. Power is listed at 40W, so it would get warm. My 185 is listed at 25W and gets only slightly warm to the touch.


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 Post subject: Re: Wavetek signal generators
PostPosted: Sep Mon 29, 2014 9:48 pm 
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The 148A has some interesting features you don't find on many function generators, which is why I bought it as surplus from the college I work at and keep it at the service bench. :)

-Mark-


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 Post subject: Re: Wavetek signal generators
PostPosted: Sep Tue 30, 2014 4:11 am 
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At first glance its a bit impressive, but performance is another matter. Used it for a couple days and it was back on the bay.Image

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 Post subject: Re: Wavetek signal generators
PostPosted: Sep Tue 30, 2014 4:47 am 
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Location: Canandaigua, NY
Face it, given that HP in the background, and other bad experiences, you just don't like Wavetek. I have an 8640B and love it dearly, but I do a lot of low frequency stuff where the Wavetek really shines. I'd certainly buy another, but only because I know how to fix them! BTW, the 8640B can have some really nasty problems too- contacts falling off the switches, debonding of the output IC and of course the shrinking cracking gears.


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 Post subject: Re: Wavetek signal generators
PostPosted: Sep Tue 30, 2014 5:52 pm 
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I got my 148A for $20.00 just to keep as a spare FG, and took it because it looked like the college hardly used it and I really didn't want to see it go to salvage. I knew it would in no way compare to the HP 3325A I have and of course it doesn't. But, in the Wavetek's defense, it's one heck of a lot better than the Heathkit IG-1275 I had in the past that is similar to it. At least the Wavetek will stabilize good after an hour warm up. The 148A can add a variety of different types of modulation to the signal, and they included a mod output so it can work as two individual function generators in one. The upper 2-20 MHz band of the base FG is nasty though, I surmise it is harmonically derived, the lower bands are OK. It's not what I consider a piece of lab grade gear, but I've seen and dealt with a whole lot worse.

-Mark-


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 Post subject: Re: Wavetek signal generators
PostPosted: Sep Tue 30, 2014 7:26 pm 
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What other analog function generators were available beside the Waveteks and the HP 202A and HP 3300A?

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 Post subject: Re: Wavetek signal generators
PostPosted: Sep Tue 30, 2014 7:50 pm 
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I have an IEC F-72 20 MHz Pulse/Fonction generator , never found the manual .


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 Post subject: Re: Wavetek signal generators
PostPosted: Sep Tue 30, 2014 7:51 pm 
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HP-8165a. A very odd function generator... although it appeared to be digital, the VCO steering voltages were set in ROM to correlate to an approximate frequency display. The display didn't offer a lot of resolution, for obvious reasons. It covered from mHz through MHz.

It has a lot of features, but the jitter and phase noise make it almost useless for sweeping narrow filters in the HF ranges.

Pete

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 Post subject: Re: Wavetek signal generators
PostPosted: Sep Tue 30, 2014 7:57 pm 
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Going back to the mid 70’s – early 80’s there were quite a few. Krohn-Hite, Tektronix 500/5000 plug-ins and a few Tek stand-alones, Leader, B&K, Simpson, Beckman, others. Wavetek had the most comprehensive line of analog FG’s though.

-Mark-


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 Post subject: Re: Wavetek signal generators
PostPosted: Sep Tue 30, 2014 8:19 pm 
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Ah, I had forgotten about Krohn-Hite. Function generators would have been right up their alley.

Pete, the HP-8165 doesn't lock to a digitally-synthesized frequency? The old Wavetek I've got uses something like the ROM trick to set the VCO voltage approximately right (probably uses a resistor matrix instead of a ROM and a DAC, though), but then phase-locks the signal to a reference generated from an RTL digital frequency synthesizer.

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 Post subject: Re: Wavetek signal generators
PostPosted: Sep Tue 30, 2014 9:07 pm 
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No, it does not lock.

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