28-07-2020, 01:20 PM
I went through exactly this recently with my HP3314A. The part number I needed was FN370-2-22. RS had close-enough equivalents for around £20, but the right part was more than £40.
I found the right part on Mouser for a sensible price, and added a few other parts to the order to reach the free shipping threshold. Very impressed with the service from Mouser - delivery was very quick indeed.
There was no opportunity to use an unfiltered unit because it combines a voltage selector and fuse(s) into a snap-in package and there's no room on the rear panel to introduce a plate to bodge a standard inlet (plus I'd have to find a voltage selector switch - not straightforward). Besides, my unit was otherwise mint, so although pricey, fitting the right part was the only option really. Just grateful the correct part was still available. The original was a little over 30 years old, so it did OK really...
I have used unfiltered replacements in other gear. Ironically, that was probably a greater sin, as they all used switched-mode power supplies. My Tek audio analyser definitely deserved better, and I will get the right part one day - some recent testing indicated that it's probably putting some hash out via the mains cable. But in most cases where I've put a simple unfiltered socket in place of the original, it was because the originals were not readily available and no equivalent could be found. For example, a Philips frequency counter that used a filter with wires emerging at right angles from the side, and there no way anything else with a filter will fit the space because the chassis practically touched the bare end of the original.
That picture looks rather like a HP8904A to me. Luckily, a friend bought one of those, meaning I don't have to! Not exactly a high point in UI design
I found the right part on Mouser for a sensible price, and added a few other parts to the order to reach the free shipping threshold. Very impressed with the service from Mouser - delivery was very quick indeed.
There was no opportunity to use an unfiltered unit because it combines a voltage selector and fuse(s) into a snap-in package and there's no room on the rear panel to introduce a plate to bodge a standard inlet (plus I'd have to find a voltage selector switch - not straightforward). Besides, my unit was otherwise mint, so although pricey, fitting the right part was the only option really. Just grateful the correct part was still available. The original was a little over 30 years old, so it did OK really...
I have used unfiltered replacements in other gear. Ironically, that was probably a greater sin, as they all used switched-mode power supplies. My Tek audio analyser definitely deserved better, and I will get the right part one day - some recent testing indicated that it's probably putting some hash out via the mains cable. But in most cases where I've put a simple unfiltered socket in place of the original, it was because the originals were not readily available and no equivalent could be found. For example, a Philips frequency counter that used a filter with wires emerging at right angles from the side, and there no way anything else with a filter will fit the space because the chassis practically touched the bare end of the original.
That picture looks rather like a HP8904A to me. Luckily, a friend bought one of those, meaning I don't have to! Not exactly a high point in UI design
