HP 8654B 10-520 MHz Sig Gen light teardown - Page 1
Forum section: electronics / testgear

author: tautech
author_rank: Super Contributor
timestamp: August 23, 2017, 12:09:50 am
content: Couldn't find mention of one on the forum so it's appropriate I share some pics.FrontRearTopNote the SMA spanner screwed to the chassis for the rigid plumbing.Top under PCBHinged PCB swung away.....still connected.Inside rearBottomWhat appears to be a cavity oscillator take a large amount of the space in the enclosure.It appears fully functional.Last Cal 2005.This unit has option 003 installed....Reverse power protection. It's a small self contained module seen on the right of Bottom image.All that was needed was some sticker residue cleaning and the frequency range knob grub screws tightened.Manual:www.ue.eti.pg.gda.pl/~bpa/lab_klb/pdfs/08654b_manual.pdf18 MbOther than the MHz range selected there is no accurate display of the output frequency so a counter need be attached for accurate settings. There are/is some adjustment available for signal amplitude and user nulling for the moving coil meter.A screenshot @ -3dB point of my SDS2304X. (~360 MHz)

author: bjcuizon
author_rank: Frequent Contributor
timestamp: August 23, 2017, 12:27:47 am
content: Nice teardown and a great score!For the sma wrench, don't you need a proper torque wrench when putting the rigid cables back in..Or does it really matter much as its just SMA connectors? (and not the precision 3.5mm and all that sort of stuff)

author: tautech
author_rank: Super Contributor
timestamp: August 23, 2017, 12:33:09 am
content: Quote from: bjcuizon on August 23, 2017, 12:27:47 amI don't think SMA was very common back in 1977 so rather than have techs grapple with them and pliersit was just easier to add a wrench under a screw on the chassis.

author: bjcuizon
author_rank: Frequent Contributor
timestamp: August 23, 2017, 12:52:12 am
content: Quote from: tautech on August 23, 2017, 12:33:09 amHehe, it is assuming that the servicemen are the ones with the grey beards who just hold their tongue at a right angle and know when and where to stop turning the connector.

author: xrunner
author_rank: Super Contributor
timestamp: August 23, 2017, 03:08:05 am
content: Cool deal. What's that component mounted at an angle (a pot or switch?). Is it due to some sort of gear arrangement?

author: TheSteve
author_rank: Unknown
timestamp: August 23, 2017, 05:01:20 am
content: It looks like a beautiful unit - thank you for sharing. It might be time for a better camera though.

author: tautech
author_rank: Super Contributor
timestamp: August 23, 2017, 05:09:33 am
content: Quote from: xrunner on August 23, 2017, 03:08:05 amIt's the mode 3 position switch for the front panel meter. The switch itself is mounted inline with the shaft so only one shaft universal is needed. You can see the switch on the front panel to the left of the meter.

author: hendorog
author_rank: Super Contributor
timestamp: August 23, 2017, 06:52:39 am
content: That's a ripper, nice one Rob.Quote from: TheSteve on August 23, 2017, 05:01:20 amRegarding the images, no doubt he has shrunk them as I know he has a very restricted connection to the interwebs.

author: TheSteve
author_rank: Unknown
timestamp: August 23, 2017, 07:20:38 am
content: Quote from: hendorog on August 23, 2017, 06:52:39 amCould be, it's a machine worthy of some nice hi-res shots, and looks to be in great shape.

author: tautech
author_rank: Super Contributor
timestamp: August 23, 2017, 07:59:53 am
content: Quote from: TheSteve on August 23, 2017, 07:20:38 amRog is quite correct, they've been compressed from 5 Mb.At some stage it's had a bump and one of the rear rails has a slight bend and the pointer lug has been broken off the amplitude selector (visible in the pics) but neither affect functionality.Anyways, I'm very pleased with the HP Sig gen, other that my SA it's the highest frequency gear I have......as yet.

author: wilgil
author_rank: Contributor
timestamp: September 22, 2017, 03:33:53 am
content: You soooooo owe me now......

author: tautech
author_rank: Super Contributor
timestamp: September 22, 2017, 04:01:11 am
content: Quote from: wilgil on September 22, 2017, 03:33:53 amI do.