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List your test equipment "scores" here!
cncjerry:
What I "need" now is a power meter, like a 436 or 437 with cable and sensor. So I'll put that out there if anyone has one that is surplus to their needs or knows a source. I've been hesitant to purchase one off eBay as I hear that the sensors are generally bad, burned out, stressed, etc. I'm sure that person who told me this is painting with a broad brush though. The 8350 setup can use an external meter for leveling to .1dBm accuracy. So not that I need that level of accuracy just that if it can be done, why the heck not? I've seen the meters for less than $75, actually have a local here with a 436 for $15 that powers on so I might pick that up a scrounge for a sensor and cable.
Now that I have el sweeper, I can test all these filters and amplifiers I've acquired to a new level of precision. I'll have to figure out how to use it with my 8566B if possible as a tracking generator. I have external mixers, directional couplers, etc so worst case I could just put the spectrum analyzer in peak hold mode.
Anyway, lots of fun.
Jerry
Neomys Sapiens:
With a start like that, I thought there will be ANOTHER story of paleo-instrumentation, but WTF?
--- Quote from: cncjerry on December 07, 2018, 11:16:44 pm ---Haven't been posting but you guys know I have a soft spot for old HP gear.
..... I found an HP 8770S/A 120Mhz arbitrary wave generator for $45. .....
Then in looking for another 10811 as I need three for the test set (not mandatory) I found an HP 8350B with an 83525A .01 - 8.0 Ghz sweeper for $135 plus shipping. ...
--- End quote ---
Tales from a mythical country. :'(
rastro:
--- Quote from: cncjerry on December 08, 2018, 04:05:20 am ---What I "need" now is a power meter, like a 436 or 437 with cable and sensor.
...I've been hesitant to purchase one off eBay as I hear that the sensors are generally bad, burned out, stressed, etc. I'm sure that person who told me this is painting with a broad brush though. ...
Jerry
--- End quote ---
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. In fact one was listed as "parts/repair - would not zero". After fixing the cracked plastic clip that holds the sensor cartage cartridge 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 cartridge.
I like the 8484's because they go down to -70dBm and you can use an18Ghz 30dB attenuator to bring it up from it's max -20dBm to +10dBm when needed. You would also need to purchase the 50Mhz calibrated 30dB attenuator to perform meter calibration. You can't use the 50Mhz for other frequencies so you would need a separate broadband 30dB attenuator for power levels up to +10dBm across the sensors frequency range.
When purchasing one of the 84XX series I would look under the 'used' category for one with the calibration chart attached. You should be able to pick up a working 8484A for around $100.00. I've run power level tests from the same signal source on several 8484A (from eBay) against their respective calibration correction charts an found they all tracked pretty close across their frequency range when using their correction coefficients. So it seems like if it is working the calibration chart is still relevant.
You may also lean toward the 437 since you can store the calibration coefficients in a frequency lookup table - some added convenience.
cncjerry:
I found a 437 last night with cable and sensor and after two offers that I've been turned down, I might just bite the bullet and buy the efing thing now. I mean come on, why would someone put BO if they're only going to take the buy it now price? Don't they know there are bottom feeders out there that need to be fed too?
The other question I have is how does one of these meters compare to a RYO using some of the AD chips? If you use a good ADC to read the DC output and calibrate it against a table, I would think some of the AD5513 and the others, can't remember the number(s), would also give them a run for the money. Wouldn't calibrating an AD5513 board with a scope and 50ohm standard be pretty accurate? Would also need multiple frequency tables I guess. The output signal would have to be amplified to the correct scale to feed the 8350 system so maybe that's a lot of work for so-so results.
Another question here, and this might not be the place, is how do these meters compare to an 8566B SA which is good to .2dBm, I think? I'll have to pull the datasheets. I think the 8566B goes to +30dBm, I know my Advantest SA does which is a little higher than most of the sensors on the 437 system. So do I really "need" the 437? ha, maybe I should move this to the TEA forum...
Darn, I guess I will try one more offer on the 437...
Jerry
rastro:
--- Quote from: cncjerry on December 08, 2018, 05:29:46 pm ---... I mean come on, why would someone put BO if they're only going to take the buy it now price?
Jerry
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eBay has recently changed their selling interface & structure. As in the past they always have specials where you can 'list' for free but are required to pay a percentage when the item is sold. Now when you choose to list, you must choose to accept Best Offer solicitations or else there is an additional opt out charge (i.e. sell with a firm price). It doesn't mean you have to accept these BO's - you just have to be open to these offers. So if you want to 'list' for 'free' you have to take the BO option. It's a stupid and petty requirement from eBay - they still make plenty with their seller fee.
--- Quote from: cncjerry on December 08, 2018, 05:29:46 pm ---...
The other question I have is how does one of these meters compare to a RYO using some of the AD chips? ...
...
Another question here, and this might not be the place, is how do these meters compare to an 8566B SA which is good to .2dBm, I think?
...
Jerry
--- End quote ---
I think the AD chips may be limited on frequency range and repeatability. They are a good value proposition for the price. There are rf power meters modules/units sold on ebay utilizing these chips. If I was going to rely on one I would characterize it against an HP power meter and then resell the HP if you are happy with the performance of the AD based measurements.
On the HP 8566/8 you may be confusing power resolution with its accuracy/repeatability. The HP 436/7 with its power sensors are significantly more accurate and repeatable. The RF path through an SA goes through RF switches and variable RF attenuators which creates mechanical repeatability issues that are not present in the 437 power meter. The SA is more a 'qualitative' instrument like an o-scope.
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