[repaired] HP 8445B input connectors replacement [+ a peek inside] - Page 1
Forum section: electronics / repair

author: ThomasHPL
author_rank: Newbie
timestamp: January 25, 2020, 03:05:42 pm
content: Hello to everyone in this lovely forum,I just got a new beauty in my lab, a really nice HP 141T +8555A and 8552B. I also got an8445B automatic preselector with it, but the two N-type connectors are kind of broken.Has anyone in here already found a fitting replacement for those?I checked on mouser, and this looks like a potential replacement, but is only specified for 12.6GHz, and is almost half the price I paid for the whole deal!https://www.mouser.be/ProductDetail/Amphenol-RF/901-295?qs=sGAEpiMZZMvlX3nhDDO4AGs0nx9o%252BG3LTYCYhl%252BPfJk%3DI'm also attaching a picture of the inside for the RF lovers

author: tkamiya
author_rank: Super Contributor
timestamp: January 25, 2020, 04:49:47 pm
content: They are plentiful on eBay. I have a few here, too. Be warned, they are relatively expensive at around 50 dollars.... HP has/had a tendency to use N connector beyond official specification. I have a several stuff N is used up to 26.5GHz. Some say they are specially made, but I found HP forum comment where HP official is explaining the discrepancy is within specification and admit that part is used beyond it's official limit.https://www.ebay.com/itm/Hp-Agilent-Keysight-Type-N-f-to-SMA-f-Adapter-08341-60001-Mount/263901942200?hash=item3d71c811b8:g:XEUAAOSwpspbiCPc

author: jfphp
author_rank: Regular Contributor
timestamp: January 25, 2020, 10:54:06 pm
content: HP used a special N connector called N Precision : the tolerances are tighter and have nothing to do with a common N connector. The limits on a N gauge are very special and, for example, a Weinschell N gauge has quite different limits on its dial comparing to a HP one (in some cases mating a Weinschell N connector with a precision HP will detroy one of the connectors). In the male HP precision the cylinder around the male pin is without the common 4 slots. Gauging the N connectors of all of the 848XX power heads gives the same value of recession of the central pin within 1/100 of an inch...N precision is usable to 22 Ghz but above there is a waveguide effect about 23 GHz and it is used well beyond to 26.5 Ghz on the 8562X and 8563X SA with a degradation in flatness response (8566B can go to 24 Ghz but it is not specfied above 22 Ghz)

author: tkamiya
author_rank: Super Contributor
timestamp: January 25, 2020, 11:56:01 pm
content: Here's the discussion I mentionedhttps://community.keysight.com/thread/7095HP rep initially says there is something special about the connector but reverses his statement later on the thread. I wonder though, if there is something special about the connector, and worse, if connecting an N connector to an N connector end up in destroying one or the other, can it be truly called an "N" connector? It kind of defeats the purpose of being a standard.Mating precision to non precision is not desirable but it shouldn't end up in destruction....

author: ThomasHPL
author_rank: Newbie
timestamp: January 26, 2020, 03:40:43 pm
content: Thank you for the very interestings precisions !I found pictures of male type N connectors without slots on the cylindre around male pin.However a document from Berkeley mention a slotless female contact for the HP precision N connectors.https://www.google.be/url?sa=t&source=web&rct=j&url=https://people.eecs.berkeley.edu/~aflynn/Cory111Lab/AGILENT_PRECISION_RF_CONNECTOR_FAQ.doc&ved=2ahUKEwits_Gjy6HnAhXOZlAKHePFBm4QFjAQegQIAhAB&usg=AOvVaw2B72PoIflJVRTlUCiN2F8LBy the way, a member of the forum, mikepi, offered to send me a couple of original HP connectors he had in stock, many thanks to him!This forum's community is awesome!

author: jfphp
author_rank: Regular Contributor
timestamp: January 26, 2020, 04:52:29 pm
content: HP Precision : WeinschellMale recession0.207----0.210 0.218---0.228Female protusion0.204---0.207 0.192---0.202Gap between 0.000---0.006Ordinary military N connectors have much larger dimensional specs, therefore always gauging connectors before use...

author: ThomasHPL
author_rank: Newbie
timestamp: February 04, 2020, 10:05:00 pm
content: I just received the package from user mikepi (he sent me two original HP connectors!)Thanks again to him, they are perfect on my HP 8445B