Hameg scope repair

[Yorkie]

Another problem with this recently acquired scope was that one of the plastic ratchets, (for want of a better word), which fit on the hinges of the handle/stand and allows the stand to be adjusted to two heights, or used as a carrying handle, was broken. The handle/stand itself was also buckled, so I guess that at some time, it must have sustained damage by something being dropped on it or whatever. However, in other respects, (apart from the damage I mentioned earlier), the scope appeared to be working.

A hinge cover was also missing, which - though cosmetic - detracts from the appearance. I put out a 'wanted' posting for a hinge cover on this and other vintage radio forums for a hinge cover, or even a scrap 203 series Hamag scope, but with no luck. However, I decided to give the EPE 'Chat Zone' a try, more in hope than expectation, but within a day, had three responses. 48 hrs later, a new hinge cover arrived FOC! I could have obtained a complete hinge set from Hameg in Germany, including the ratchets, but it wouldn't have been cost effective. I decided to make a pair of replacement ratchets from brass as they'de be more robust.

I obtained two brass discs of the right thickness turned down to size from a 2" bar by a model engineer chum in the village, and a piece of 6mm brass rod on e-bay. I tunred a recess in the discs for a washer that has to fit between the disc and the stand/handle, then drilled and filed the discs to shape - on left hand, one right hand, using the old plastice ones as templates. Each disc has three short 6mm diam pegs which locate in holes in the side of the scope cabinet.

I considered simply drilling three holes through each disc and using C/S brass nuts and screws, but that seemed a bit of a lazy bodge, so I opted for making the discs as near as the brass ones as possible. I therefore decided to turn the pegs down to 4mm to form a rivet, and drilled a 4mm hole through the three points on each disc where the pegs needed to go. I then drilled a 6mm concentric hole, in each 4mm hole, then used a 6mm end mill fixed in my pillar drill to create a shoulder in the holes so that the peg would fit neatly in the hole, with its 4mm end protruding through the rear.

I countersank the holes on the rear to allow the protruding 4mm ends of the pegs to be peened over into a rivet to fix the pegs firmly, then tidied up the rivent head. My little Lorch lathe came in handy to turn the pegs, and it was a bit of a finnicky task to turn the 6mm rod down to 4mm to be a tight fit in the hole. Just a smidgen too much removed on a lathe is actually two smidgens on the diameter, so I constantly cheked till I got a good fit!

I've attached a few pics of the progress of this little job, which was actually quite time consuming. I've included a pic of the orginal plastic discs, where the damage to one will be noted.

Also, a pic of the two traces of the scope showing the 2V and 0.2V inbuilt calibration square wave traces.

Hope it's of interest.