Hi Hal,
Those oscillators are perfect for many jobs. I keep something simpler and nastier on the bench for those occasions. I wish it was a 209A!
Also, many thanks for interjecting. I'd say you're right as for the motivations of many here. Also for me.
Hi Ixnay,
I really don't mean to be down on you at all. Sorry, but I am very blunt and direct. Partly because that's my character, and also due to technical training. So please, do not take what I say personally, it isn't intended that way at all. If I make a personal comment, you'll know it without a doubt. Besides, egos don't survive the training I got. I just argue on right and wrong.
Those oscillators are perfect for many jobs. I keep something simpler and nastier on the bench for those occasions. I wish it was a 209A!
Also, many thanks for interjecting. I'd say you're right as for the motivations of many here. Also for me.
Hi Ixnay,
I really don't mean to be down on you at all. Sorry, but I am very blunt and direct. Partly because that's my character, and also due to technical training. So please, do not take what I say personally, it isn't intended that way at all. If I make a personal comment, you'll know it without a doubt. Besides, egos don't survive the training I got. I just argue on right and wrong.
The 209A probably won't go on the bench, just on a collectables shelf. For low frequency work I have both a 3326A and a 3335A in the rack (and a 8663A for the higher stuff) since for what I do I am concerned with the level as much or more than the frequency. I do have a 239A for when I need something with lower distortion, though. For all that, I do have a love of the early HP oscillators and have generally been trying to get a good example of various models as I find one worth having. My earliest so far is a low SN 200A - not early enough that it was built in the garage but still very nice to have.
Very nice Hal!
I have a bunch of oscillators also, RF and LF. But sometimes twisting a knob is easier and faster for things that aren't as precise. I find the same with power supplies at times. If you have known frequencies and levels, then the more modern units I have work great. For LF i use an HP 3325A or 8904A. Very often I'll use the audio analyzer too (RTX 6001).
A 239A? Cool! I use my 339A (same osc.). I have an HP square wave oscillator, really early tube. I can't remember the model #, it's in the garage waiting restoration. That thing is huge with a big wood case. Your 200A is amazing, very cool!
I have a bunch of oscillators also, RF and LF. But sometimes twisting a knob is easier and faster for things that aren't as precise. I find the same with power supplies at times. If you have known frequencies and levels, then the more modern units I have work great. For LF i use an HP 3325A or 8904A. Very often I'll use the audio analyzer too (RTX 6001).
A 239A? Cool! I use my 339A (same osc.). I have an HP square wave oscillator, really early tube. I can't remember the model #, it's in the garage waiting restoration. That thing is huge with a big wood case. Your 200A is amazing, very cool!
I don't have a 339A - it would be nice though. Of everything that I have managed to collect, probably the rarest is a HP 5103A synthesizer. I have a 5100A as well as a 5105A along with the 5110B drivers, but the 5103A is the only one that I have never seen elsewhere, for sale or not. Sure that there are but not that I've seen. I am very much looking forward to restoring them all one day along with several other "me" pieces. They are all just amazing things to look at how they were constructed - I think there are pictures on the HP Museum and/or archives. They simply boggle.
The 339A is easier to find. Most knobs are either cracked or the lettering has come off. It would be great if someone made new knob blanks and lettering decals!!!
Those are so cool! I barely noticed them in passing before you mentioned them specifically. I thought it was amazing how they did the frequency displays back then, and you brought them back to my attention. I had to look them up again to remember what they were.
Projects of love. There will be a lot of careful work there. I restore tube products as well, and removing / installing parts takes ages to do properly. I would say that you need to get your axial capacitors very soon as they are going out of production. They are getting very dear as well.
Just imagine, one day there will be nothing but surface mount parts - or something we can't even imagine today.
Those are so cool! I barely noticed them in passing before you mentioned them specifically. I thought it was amazing how they did the frequency displays back then, and you brought them back to my attention. I had to look them up again to remember what they were.
Projects of love. There will be a lot of careful work there. I restore tube products as well, and removing / installing parts takes ages to do properly. I would say that you need to get your axial capacitors very soon as they are going out of production. They are getting very dear as well.
Just imagine, one day there will be nothing but surface mount parts - or something we can't even imagine today.
I just ordered a bunch of them today - mostly 100uF to 330uF. Personally I tend to replace for function not form and am happy to use a little kapton tape or PTFE tubing on leads to use radials. The ones that seem to just not have enough room or otherwise not be suitable for radials tend to be in the low ranges such as those I just ordered. While I like the original equipment look it is just not possible to duplicate that with modern parts for the most part. When I make an exception to that is usually with the can capacitors in tube equipment - those I will often restuff or disconnect and use modern parts underneath the chassis. A high quality pipe cutter works very nicely to cleanly open the cans, BTW... I use a Wheeler-Rex 4992 since it has a lot more support for the tube while cutting and has a sharper than average cutting wheel/
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Hi Hal,
Caps inside a can can't dissipate heat effectively. I always use the CE manufacturing caps, and duties and clearing fees cost me huge! I find the axial caps just fit and work better.
Back in early days we used axial caps everywhere because radial caps were not readily available. I laugh when I see an early unit done that way, but we had no choice at all. I just completed this amplifier. I do as I say I do. I used the main filter capacitors the previous guy installed. They work fine but are a pain to connect to.
Caps inside a can can't dissipate heat effectively. I always use the CE manufacturing caps, and duties and clearing fees cost me huge! I find the axial caps just fit and work better.
Back in early days we used axial caps everywhere because radial caps were not readily available. I laugh when I see an early unit done that way, but we had no choice at all. I just completed this amplifier. I do as I say I do. I used the main filter capacitors the previous guy installed. They work fine but are a pain to connect to.
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Nice work... as with so many things it depends on what you are trying to accomplish. Beyond basic neatness I think that with what you do there is significant importance put on the "look" of the internals as that is of importance to your customers and end users. With me, they want a box that is dependable, stable and can be sent out for an accredited cal with no worries. IMO, a lot more expense and artistry required for you than me - thankfully! I can do form but it doesn't come naturally or easily for me - and you certainly have my admiration for having the patience and skill to do so.
As for new on the bench, this just came in. I have always had a lot of admiration for Power Designs supplies as they are pretty much bullet proof and not only "just work" but they do it well and will outlast all of us. With one of these I like to modify them by replacing the front current limit trimers with actual pots with knobs - and with a integrated push/pull switch to short the output to make it easy to set the current limit.
As for new on the bench, this just came in. I have always had a lot of admiration for Power Designs supplies as they are pretty much bullet proof and not only "just work" but they do it well and will outlast all of us. With one of these I like to modify them by replacing the front current limit trimers with actual pots with knobs - and with a integrated push/pull switch to short the output to make it easy to set the current limit.
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Thanks Hal,
I love those supplies. Perfect for working on smaller power amps! Nice. If we were closer I'd try to buy one from you. Your mods make sense.
I use HP 6186 B & C current sources for some work. Valuable things to have.
I also work for reliability. I am used to test equipment where parts placement is sometimes critical. I don't work to be pretty, although it may seem that way. I can also tell instantly if someone else messed with one of my jobs! lol! The fact they look neat makes it easier to check my own work, customers normally aren't inside. The few that are at least understand the work that went into their units. When it is test equipment, I think it is even more important to have things right. That's just my lab training, so I work that way all the time.
I clean the areas I work in so I can see if anything made smoke. Makes troubleshooting easier later than if it was marked by earlier problems. Same reason they clean and paint engine blocks.
I love those supplies. Perfect for working on smaller power amps! Nice. If we were closer I'd try to buy one from you. Your mods make sense.
I use HP 6186 B & C current sources for some work. Valuable things to have.
I also work for reliability. I am used to test equipment where parts placement is sometimes critical. I don't work to be pretty, although it may seem that way. I can also tell instantly if someone else messed with one of my jobs! lol! The fact they look neat makes it easier to check my own work, customers normally aren't inside. The few that are at least understand the work that went into their units. When it is test equipment, I think it is even more important to have things right. That's just my lab training, so I work that way all the time.
I clean the areas I work in so I can see if anything made smoke. Makes troubleshooting easier later than if it was marked by earlier problems. Same reason they clean and paint engine blocks.
Oh, I'm a neat and clean fanatic myself - just don't particularly care if it matches the original appearance. For troubleshooting one of the most useful things I have is a nice thermal camera - I use a HTI HT-19 currently - and it is truly one of the things I wonder how I ever managed to get by without.
Now that is something I have wanted since they became available!! My thermal sensor is purely digital .... my finger (ouch!). lol!
I am waiting until more affordable units become available that have a high enough resolution. Probably used or new Chinese manufacture.
Component location can matter - depending. Wire and component routing is engineered and the equipment is characterised the way it is manufactured. I hate uncertainty and I would rather put it the way it should be (hopefully was) than troubleshoot my construction. I have experienced this in the past, and that taught me to just do it the way it was.
I am waiting until more affordable units become available that have a high enough resolution. Probably used or new Chinese manufacture.
Component location can matter - depending. Wire and component routing is engineered and the equipment is characterised the way it is manufactured. I hate uncertainty and I would rather put it the way it should be (hopefully was) than troubleshoot my construction. I have experienced this in the past, and that taught me to just do it the way it was.
Yes, I used the Mark I finger for too long... Problem is that the sensitivity decreases with use as the scars build up ;-)
You are absolutely correct with how important the layout is - something lost on a lot of the newer players. After all, a wire or component lead is just an antenna in the end. As you pointed out earlier the world is full of RF that was not present when a lot of this was originally designed - something that I would think is a much larger problem for you with the typical lack of shielding on consumer gear. My stuff tends to have good shielding from the start - admittedly originally designed to keep the RF in but happily works just as well in the other direction.
You are absolutely correct with how important the layout is - something lost on a lot of the newer players. After all, a wire or component lead is just an antenna in the end. As you pointed out earlier the world is full of RF that was not present when a lot of this was originally designed - something that I would think is a much larger problem for you with the typical lack of shielding on consumer gear. My stuff tends to have good shielding from the start - admittedly originally designed to keep the RF in but happily works just as well in the other direction.
lol! on both counts Hal!
LMAO!!!
Thankfully I don't work on new stuff so much. New test gear isn't build very well, and it is susceptible to RF compared to the older equipment. There is almost nothing nicer than working on an older piece of HP or similar equipment. New audio? Most is pure junk and difficult to work on. Plus, it is designed to fail and is not well engineered. Even traces and pads are not up to snuff. In short, it is not made to service. No matter how careful you are, pads and traces can lift. That and everything is very time consuming to get into. Only some of the better brands are even worth opening up. Also, heat buildup is the biggest issue with new test gear and new consumer crap. Thank god I'm old and do not have to service this new (insert description of your choice).
LMAO!!!
Thankfully I don't work on new stuff so much. New test gear isn't build very well, and it is susceptible to RF compared to the older equipment. There is almost nothing nicer than working on an older piece of HP or similar equipment. New audio? Most is pure junk and difficult to work on. Plus, it is designed to fail and is not well engineered. Even traces and pads are not up to snuff. In short, it is not made to service. No matter how careful you are, pads and traces can lift. That and everything is very time consuming to get into. Only some of the better brands are even worth opening up. Also, heat buildup is the biggest issue with new test gear and new consumer crap. Thank god I'm old and do not have to service this new (insert description of your choice).
More on the thermal camera - they are good for saving you from your own goofs. Designed a HV, HF amp a few months ago... got the boards in, built the first one... didn't work... thermal camera out, all transistors hot. Hmmm. Seems that I forgot one of the basics: Thou shalt check thy transistor pinouts when changing part numbers. Luckily I wasn't a complete idiot and had brought it up with slowly increasing voltage and current limiting so all of the Magic Smoke(tm) was preserved. Quick de-solder, twist 180 degrees and solder. Worked a whole lot better after that 
Yes, that is an excellent use, and one I had in mind. Also for properly running new designs just to make sure things are sitting at reasonable temperatures.
I've made similar errors with changing transistors types enough! Especially if you're tired and change transistor types. I get a lot of unrepairable equipment in suffering from that, so you are by no means the only one!
I've made similar errors with changing transistors types enough! Especially if you're tired and change transistor types. I get a lot of unrepairable equipment in suffering from that, so you are by no means the only one!