[Test-Equipment] Crystal Marker Boards for HP 675A Sweeping Signal Generator

[Dale H. Cook]

At 09:31 PM 5/22/2014, Pete Lancashire wrote:

>The help I was thinking was getting boards made, if can do it with two
>layers it is not that much.

They are ca. 1968 two-sided boards, and I can fabricate those easily enough - the layout is simple and the parts count is low.

>Did you check the xtals yet

Not yet - I pulled them out of my boxes of unused crystals, but haven't yet had a chance to test them. First I need to finish building a test bed for the RF power amp boards for a series of low-power AM broadcast transmitters. I have a bad board that I need to repair, adjust, burn in and test for a customer.

> .. wish I had the room to put the thing on the bench

Mine sits on top of the older, larger, heavier, and definitely more brutal General Radio Type 605-C standard signal generator:

http://plymouthcolony.net/starcity/radios/pages/compact.html#bench3

While I had the 675A open this morning I did a repair/mod that I've intended to do for a while. The power switch was occasionally flaky, so I wanted to replace it, but I turned the repair into a modification. The oven runs whenever the line cord has power, but there are times when I may go 2-3 weeks without using the 675A, and there are times when the bench is powered up for an extended period for a burn-in, and I dislike leaving something on which is not needed. It is a nuisance getting to either end of the 675A power cord in my shop.

I replaced the SPST power switch with a DPDT center-off switch. The oven power comes from the power switch, so I split that off. When the new switch is in the center position everything in the 675A is off and the on and standby indicators are both off. With the switch in the down position the oven is on and so is the standby indicator. With the switch in the up position everything is powered up and both indicators are on. I can stand the 20 minute oven warmup time. I don't really need the 8 hour warmup for maximum CW stability.

>BTW if you know some that has a junker, I'm looking for one of the plastic bezels that go where the Veeder-Root counters are.

I don't know of one but will keep my eyes peeled.

Dale H. Cook, GR / HP Collector, Roanoke/Lynchburg, VA
http://plymouthcolony.net/starcity/radios/index.html