Forums :: Resources :: Features :: Photo Gallery :: Vintage Radio Shows :: Archives :: Books
Support This Site: Contributors :: Advertise


It is currently Oct Wed 24, 2018 5:38 am


All times are UTC [ DST ]





Post New Topic Post Reply  [ 8 posts ] 
Author Message
 Post subject: HP 5342A counter
PostPosted: May Wed 16, 2018 6:52 pm 
Member

Joined: Nov Thu 07, 2013 3:29 am
Posts: 210
Location: Leesburg, Virginia
Fell into the curatorship of this beast. Question for someone who happens to be familiar.

It powered on but did not complete the self test. Discovered the 10MHz oscillator signal was not making it to the buffer. Said signal, I thought, (looking at the online scanned manual) simply ran via a trace on the A22 'motherboard' to the A18 buffer. Said path measured 'open' and I saw a silkscreen line between the appropriate connectors marked '10Mhz'. Installed a jumper.

Success. A 1.5Vpp time base signal now appears at the buffer. And, the self test completes. And at least on the 'low side' input (10Hz-500MHz) it is working and accurately.

This was just too easy. Other than the silkscreen line I can see no sign of a jumper being removed. It seems unlikely a trace could have been blown. Was there originally a jumper here? Not a trace? Someone removed?

There are remaining issues but this jumper seems to have fixed the first hurdle. I just can't believe it.

Anyone active on the HP Yahoo group know if they plan to join the exodus to groups.io?

Thanks

_________________
JI
W0MPM


Top
 Profile  
 
 Post subject: Re: HP 5342A counter
PostPosted: May Wed 16, 2018 8:50 pm 
Member

Joined: Sep Tue 30, 2014 6:08 am
Posts: 3169
Location: The Old Dominion VA 23518
Two possibilities - 1)it was installed in a test station, and used an external clock oscillator, or 2)used a loop-back scenario that required a jumper (not sure of the option number, but 5328A's had this option as an interlock of sorts).

My money is on #1. I used to scour Hamfests and find HP and EIP freq counters cheap (doesn't work...) only to find the int/ext clock switch in the ext position, or a missing oscillator.

_________________
Brian
"Capacitor Cosmetologist since 1979"
USN Retired 1984-2006 (Avionics/Cal)


Top
 Profile  
 
 Post subject: Re: HP 5342A counter
PostPosted: May Wed 16, 2018 9:24 pm 
Member
User avatar

Joined: Jan Thu 01, 1970 1:00 am
Posts: 33378
Location: Maryland 20709, USA
The 5342A counter DOES have provision for an external 10MHz timebase.
That input is via the left-most (of 4) BNC connector at lower right of the rear panel.

There is an associated slide switch to the left of that BNC that selects INT or EXT reference.
It must be in the INT position to use the internal timebase (obviously).

Operator manual on BAMA here:
http://bama.edebris.com/download/hp/534 ... OpInfo.pdf

- Leigh

_________________
73 de W3NLB
http://www.AtwaterKent.info
Click "Grebe Stuff" for Synchrophase info


Top
 Profile  
 
 Post subject: Re: HP 5342A counter
PostPosted: May Thu 17, 2018 12:26 am 
Member

Joined: Nov Thu 07, 2013 3:29 am
Posts: 210
Location: Leesburg, Virginia
Thanks guys. The time base source is switched internally on the A18 buffer board (via the switch on the back which switches 5Vdc on the board).

Almost enough to make me regret cancelling all Yahoo registrations. Ah ... No it's not.

_________________
JI
W0MPM


Top
 Profile  
 
 Post subject: Re: HP 5342A counter
PostPosted: May Thu 17, 2018 1:35 am 
Member
User avatar

Joined: Jun Wed 08, 2011 2:33 am
Posts: 7263
Location: Ohio 45177
I had one of the big HP counters with the yellow LED display as I recall, and a very very good oven time base. But it was big and bulky and a fan in it. Finally settled on a much smaller 5385A which is so much smaller and handier. Only drawback the LCD is not backlit in case you don't have good lighting shining on it. And the time base is an TXCO which is good enough for most things but no oven. But I can either cal it against Rubidium or just plug that into the ext. clock. But they say Rubidium is not as clean as a really good xtal oscillator output. Could get a surplus GPS base for about twice what I payed for the atomic, but avoids the potential weakness of sat downlinks.


Top
 Profile  
 
 Post subject: Re: HP 5342A counter
PostPosted: May Thu 17, 2018 10:33 pm 
Member

Joined: Feb Wed 25, 2009 4:06 pm
Posts: 1320
Location: Morristown, N.J.
Service departments often have under-qualified techs who might simply “borrow” a jumper from one unit to put into another and then forget about the donor instrument. The donor eventually finds its way onto a pallet of other “unserviceable” instruments and dumped as a whole. In the past I’ve relied on these instruments, sight unseen, for my workbench and done extremely well.

Thirty years at HP as a tech/engineer gave me an insight as to potential bargains and I haven't lost yet.

_________________
Pete AI2V

"It's always darkest before it's pitch black"


Top
 Profile  
 
 Post subject: Re: HP 5342A counter
PostPosted: May Fri 18, 2018 12:17 pm 
Member

Joined: Nov Thu 07, 2013 3:29 am
Posts: 210
Location: Leesburg, Virginia
Well. Curiouser and curiouser. Looking at a second unit and the same thing. Big 3Vp-p 10MHz at motherboard (A22) connector XA24 pin 15 and -15 but not at XA18 pin -8. And infinite ohms between the two. Schematics would indicate a simple hard connection between the two. But I see no sign of anything ever being removed.

So while adding the jumper did restore some functionality to the first unit and presumably might to this one (they each have other things going on) it's not clear to me I actually 'fixed' anything. In fact I rather doubt it.

Anyone have a working 5342A to compare?

_________________
JI
W0MPM


Top
 Profile  
 
 Post subject: Re: HP 5342A counter
PostPosted: May Fri 18, 2018 11:02 pm 
Member
User avatar

Joined: Jan Thu 01, 1970 1:00 am
Posts: 33378
Location: Maryland 20709, USA
OK. Just found a schematic of the counter.

My __assumption__ about how the rear panel BNCs worked was wrong.

The slide switch provides a logic-level control signal to the A18 Timebase Buffer.
It selects between two possible paths for the 10MHz source to the buffer amp.

The logic tree is such that one or the other MUST appear at the buffer input.
That signal should appear at A18 Test Point 1, and via an amplifier at the rear panel BNC.

Connect an external 10MHz source to the EXT input BNC to see if it gets through.

- Leigh

_________________
73 de W3NLB
http://www.AtwaterKent.info
Click "Grebe Stuff" for Synchrophase info


Top
 Profile  
 
Post New Topic Post Reply  [ 8 posts ] 

All times are UTC [ DST ]


Who is online

Users browsing this forum: No registered users and 10 guests



Search for:
Jump to:  
























Privacy Policy :: Powered by phpBB