I've had close to a dozen HP 8484A sensors from eBay over the last 5 years pass over my workbench and have had pretty good luck. I can't remember receiving any from eBay's "used" category being bad. I've also bought a few listed under "parts/repair" as unknown that also checked out OK.
I've had close to a dozen HP 8484A sensors from eBay over the last 5 years pass over my workbench and have had pretty good luck. I can't remember receiving any from eBay's "used" category being bad. I've also bought a few listed under "parts/repair" as unknown that also checked out OK.The 8484A is a diode sensor. The thermocouple sensors like 8481A and 8482A may very well be different. Despite their higher maximum power levels, they appear to die more frequently. Probably because they are more sensitive to overloads. And there appears to be almost no chance of repairing them given the lack of spare parts and special skills available if the thermocouple is blown.
After fixing the cracked plastic clip that holds the sensor cartage wires to the PCB it zeroed and calibrated fine. Yes you would need to have it re-characterized if you move or mess with the sensor cartage.
You may also lean toward the 437 since you can store the calibration coefficients in a frequency lookup table - some added convenience.
I've had close to a dozen HP 8484A sensors from eBay over the last 5 years pass over my workbench and have had pretty good luck. I can't remember receiving any from eBay's "used" category being bad. I've also bought a few listed under "parts/repair" as unknown that also checked out OK.The 8484A is a diode sensor. The thermocouple sensors like 8481A and 8482A may very well be different. Despite their higher maximum power levels, they appear to die more frequently. Probably because they are more sensitive to overloads. And there appears to be almost no chance of repairing them given the lack of spare parts and special skills available if the thermocouple is blown.
If someone says "for parts or best offer" and then you ask them if it powers up and they tell you it does but they cant test it further but then it doesn't power up when you get it, instead it blows a fuse.. who is right? What to do?
If someone says "for parts or best offer" and then you ask them if it powers up and they tell you it does but they cant test it further but then it doesn't power up when you get it, instead it blows a fuse.. who is right? What to do?Then you make a claim with the seller and tell him it is not as described and make arrangements for a lower price (partial refund) or return it for a full refund. Most sellers will agree to a partial refund in my experience.
After fixing the cracked plastic clip that holds the sensor cartage wires to the PCB it zeroed and calibrated fine. Yes you would need to have it re-characterized if you move or mess with the sensor cartage.
You may also lean toward the 437 since you can store the calibration coefficients in a frequency lookup table - some added convenience.What is the assumed meaning of 'cartage'?
I thought the 'D' power sensor models were the diode type? for instance 8481d, 8482d, etc.
Thanks for all the input. This is all complicated but I'm starting to understand what I need.
thanks again. still debating. Now I'm thinking I want a 438 instead of a 437. I found sensors in the 150 range, cable in the $50 range and I can get a 438 for around 150 or less. So for 350 I can get one channel configured and then work on the second at a later date. The power sensors look like the are very band and range specific. If doesn't look like many have more than about 50db of range. So it looks like you have to have a stack of attenuators.
And Orin, nice to hear from you, hope all is well up north. I'm still taking good care of your Geller standard and will repay the favor someday I hope. Playing with any 3456s lately? I still have one in the garage a patient gentleman sent me to fix about 18 months ago and though I said "at my convenience" I think this is pushing it and I should get a move on. They are fun to fix on a rainy day.
Jerry
On your 8566B, though I am against wholesale cap replacement, I had a leaky cap on one of the supplies so they do fail. The supply was like the -10V or 10V, can't remember exactly, but the cap was a Sprague Powerlytic, 13000uf at 25V. The next time you have the RF unit it on its side you might want to check the ESR of some of the caps. Mine just game me unlocks and other silly errors, fuse stayed ok.
Jerry
I was mostly blaming the mains for that fuse. As the local area developed more houses ware added to the already long line to the transformer substation, additionally heat pumps became a popular way of heating homes here and that put a heavy load on the grid here. As a result i would get fairly low voltage in the mains of around 210 to 220V, this caused the HP 8566B brown out and reboot on a few occasions as it was set for 240V. To fix that i changed the mains selector to 220V and it was fine. In the mean time dad had a solar array installed and things got even worse, to the point where the solar inverter was throwing errors. So i set up a DMM to log the mains voltage over a few days and was shocked to find out it would at times dip to 180V while other times rise to 245V. I shown the graph to the power company and they hooked up there own voltage logger to indeed find the voltage is way out of spec. After some back and forth they finally ran a dedicated new line from the transformer station for this area. And that made the voltage rock solid.
By the way, many of the cylindrical silver caps are not electrolytic but tantalum, expensive little devices. I picked up a couple of thousand of various values from a guy who repaired Tek and HP scopes. Let me know if you need any by PM.
Jerry