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Diabolical Artificer · 13th Apr 2017, 3:55 pm

A bit more done but a few mistakes made. The amp chassis is 7 1/2" by 12 1/2" and sits between two end pieces like the cross bar on a H. I mounted this 2" above the amp case floor, but this meant that the OPT hit the amp case top cross bar, so therefore wouldn't be able to slide in. So had to lower it.

Lowering it to 1 and 13/16" maent that the CCS heatsink was too "high" ( see pic 1) and would hit the bottom of the case. So off with the old HS but I didn't have one suitable so I had to cut one off an old car stereo HS that I've had in the junk box for years but was too weird to be used. This meant bodging the CCS board a bit, but not too badly.

I've also hit a potential snag with the chassis power connector (see pic 2) which came off the old Tek scope. It's a McMurdo red series RSD16, which ITW still make. I wasn't going to butcher the Tek plugin so had to buy the male connector. These ain't cheap at £21.83 each, but I found some in Oz at £4.50 each so got 6 which makes the postage cost ok.

However reading the datasheet - see attached - it says contacts = 5A "All contacts (simultaneously)" which may mean each pin/contact is rated at 312mA each. This means that I'll need to double up the pins for the HT and ground and use eight (or would it?) for one 18.9v 1.5A heater supply. Each pin is 19 thou thick by 1/8" wide. The McMurdo octal socket pins are 15 thou thick by 3/16" roughly and I presume they were designed with the idea that valves like the 5U4G which has a htr current of 3A, could be used. looking at similar/suitable type connector's, the Amphenol blue ribbon connector which is similar has a pin rating of 5A. Looking at the Tek plug ins I have two that use 15 small valves like the 12AT7/6AU6. At a rough estimate that would be 15 x 300mA = 4.5A. As far as I can see Tek used only two pins for the htr wiring loom, so maybe I have it wrong and am talking bo*****s. Feedback most welcome.

The amp chassis bolts will be counter sunk and the front plate will have a thin plate on top, as per Tek scope and plug in.

That aside here's some more pics....

Andy.

13th Apr 2017, 3:55 pm	#161
Diabolical Artificer Dekatron Join Date: Jul 2009 Location: Sleaford, Lincs. UK. Posts: 7,667	Re: 807 (maybe) amplifier build. A bit more done but a few mistakes made. The amp chassis is 7 1/2" by 12 1/2" and sits between two end pieces like the cross bar on a H. I mounted this 2" above the amp case floor, but this meant that the OPT hit the amp case top cross bar, so therefore wouldn't be able to slide in. So had to lower it. Lowering it to 1 and 13/16" maent that the CCS heatsink was too "high" ( see pic 1) and would hit the bottom of the case. So off with the old HS but I didn't have one suitable so I had to cut one off an old car stereo HS that I've had in the junk box for years but was too weird to be used. This meant bodging the CCS board a bit, but not too badly. I've also hit a potential snag with the chassis power connector (see pic 2) which came off the old Tek scope. It's a McMurdo red series RSD16, which ITW still make. I wasn't going to butcher the Tek plugin so had to buy the male connector. These ain't cheap at £21.83 each, but I found some in Oz at £4.50 each so got 6 which makes the postage cost ok. However reading the datasheet - see attached - it says contacts = 5A "All contacts (simultaneously)" which may mean each pin/contact is rated at 312mA each. This means that I'll need to double up the pins for the HT and ground and use eight (or would it?) for one 18.9v 1.5A heater supply. Each pin is 19 thou thick by 1/8" wide. The McMurdo octal socket pins are 15 thou thick by 3/16" roughly and I presume they were designed with the idea that valves like the 5U4G which has a htr current of 3A, could be used. looking at similar/suitable type connector's, the Amphenol blue ribbon connector which is similar has a pin rating of 5A. Looking at the Tek plug ins I have two that use 15 small valves like the 12AT7/6AU6. At a rough estimate that would be 15 x 300mA = 4.5A. As far as I can see Tek used only two pins for the htr wiring loom, so maybe I have it wrong and am talking bo*****s. Feedback most welcome. The amp chassis bolts will be counter sunk and the front plate will have a thin plate on top, as per Tek scope and plug in. That aside here's some more pics.... Andy. Attached Thumbnails __________________ Curiosity hasn't killed this cat...so far.