Products > Test Equipment
HP8640B-opt323: Should I return it?
tatel:
This military version of HP8640B is my first piece of RF equipment, not counting a dummy load.
Matter is:
a) FM deviation knob jumps over some detents going CW, then knob marks do not coincide with detents. Going CCW, it also jumps some detent, but not so much, and knob marks again coincide with detents. I'm afraid this could mean gears are bad. See it here: https://youtu.be/Zajaf_QCRI0
b) Output level is lower when the knob is on 20 dBm mark than on 10 dBm mark (meter maxes out here). Vernier knob is fully CW in both cases. WTF? See it here: https://youtu.be/GjVMWE5l6xA
So, what the old wise men think about it? Should I return it?
tatel:
Vendor says it was in "perfect working condition" when shipped. :-DD
Please enjoy attached pictures.
Stray Electron:
If you bought it from E-bay then you're entitled to return it and to get absolutely full refund, including the shipping costs, if it was categorized as working. Even if it was described as "As-Is". Ebay and PayPal are both quite clear about that.
That said, the 8640s are quite old and are well known for having these types of problems so if you really want one then you might have to grit your teeth and keep this one and try to fix it. I'm very skeptical about the chances of finding any 8640 that doesn't have the same problem. But depending on how much you paid for it, you're probably entitled to at least a partial refund. Unfortunately that is up to the seller and if he refuses to give you a partial refund then you're either going to have to return it for a full refund or keep it and get nothing.
I can't tell how many gears in yours are cracked but as of a few years ago there were NO replacements for those so if it were me I would return it and give up on buying an 8640. I passed on one in a surplus store a few years ago for $25 because I could tell that it had similar problems and, to me, it wasn't worth the effort that it would require to fix it. Even if it was possible.
ZigmundRat:
To return it or not I guess depends on what you want to do. But these units (I had one for years) are notorious for broken gears. In fact it would be surprising to find one today with them intact. These are commonly repaired with a tie wrap around the body to hold them together. But you can also get replacements - there’s a fellow in India selling brass ones on eBay. Either solution is a fairly straightforward mechanical repair.
The output control is another matter. It sets the max for that range. If the vernier is fully CCW, it should not pin the meter. It should be variable from something below 10dB down from max, up to full scale. It sounds like you may have a problem with the attenuator, in which case I would return it. They are usually not repairable. (At least easily.)
tatel:
--- Quote from: Stray Electron on June 22, 2023, 10:11:23 pm --- If you bought it from E-bay then you're entitled to return it and to get absolutely full refund, including the shipping costs, if it was categorized as working. Even if it was described as "As-Is". Ebay and PayPal are both quite clear about that.
--- End quote ---
Yep. Unfortunately no eBay nor Paypal used. This is a surplus seller. So he has a reputation and a business to take care of. Since we are still negotiating, all I can say is: if there is no acceptable solution by Wednesday, you will know which vendor it is.
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