the value of old test and repair equipment

drlegendre . drlegendre at
Sat Aug 6 20:16:34 CDT 2016

Though I have some background in Telcom, I'd never heard of the HP 3370(B)
so had to check it out.  Here are a couple of take-away quotes from a
thread at:

"The A suffix boxes were designed to test phone lines for modems for CCIT
standards (UK & Europe), the B suffix (B-for-Bell) were the for the
American market. Designed and built in South Queensferry.

You use a pair of 3770s one at each end of a leased phone line connection.
One transmits to the other and vice-versa and they measure frequency
response and group delay. The purpose was to assess lines for modem use.
The firms who leased lines used these boxes to check they were getting the
quality they were paying for. The telcos used these boxes to make sure the
lines they were leasing out weren't below contract performance and going to
cost them penalties. Nice business for the instrument makers."

"They were around 12 kilobucks each back in the day. I think the 3770 did
level, flatness and distortion, I think the 3771 did group delay come to
think of it. My pilot tone filter probably did go in the 3770."

As I was assuming, they are used in pairs at opposite ends of the line.
Neat device.

On Sat, Aug 6, 2016 at 7:14 AM, tony duell <ard at> wrote:

> I also collect old/classic test gear. Some I use (my main
> 'scope is a Tekky 555, I think that's old enough to be a
> classic :-)). Some I just collect because it's a beautiful
> piece of electronics. My latest find was an HP3770B
> telephone line analyser -- an instrument to measure the
> freqeuncy response, etc of a telephone line. I have no
> real use for it, but it's classic HP, built like a brick outhouse,
> designed to be repaired (fixing screws are labelled, there
> are testpoints for everything, there's even an extender board
> stored inside). I had to add it to the collection.
> >
> > I've been restoring a HeathKit capacitor checker.
> >
> > I also have a couple HP counters with Nixies.
> Ditto. Mine have those HP counter boards with 8 transistors
> as the counters, 8 neons as the latch and a thick film CdS
> photoresistor array to drive the nixie tubes. 5243 and 5245 I think.
> >
> > I even have a 10 channel printer ( need to repair the
> >
> > roller ). I've found that one doesn't need the expensive
> >
> > ink roller ( though I'd love to have one, used or not ).
> >
> Is that the HP5055. I've rebuilt one. Be warned the printer
> motor runs off the mains, and that therefore there's mains
> on some PCB traces where you might not expect it.
> Interestingly the HP59301 HPIB-> 64 bit parallel interface
> can be connected directly to the HP5055 printer. There
> are 2 conenctors on the interface, one carries 40 bits
> the other 24. The 40 bit one links to the 5055 with a straight-wired
> 50 pin microribbon cable. The alternative character set for
> the HP59301 was clearly designed for this, it decodes ASCII
> V,A,O into the V, A, Ohms symbols on the 5055.
> > I use the two layer impact paper.
> Mine had an ink roller in it _and_ the impact paper. The fomer
> was doing a good job of gunging everything up, so I removed
> it and stored it in a plastic bag.
> -tony

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