[ARC5] BC-453 in operation.

[Brian Clarke]

Hello Ken,

I thought I had seen many of your videos before, but not this one. Great
stuff.

I used a BC-453 to demonstrate to tech college students the sub-microvolt
capability possible with careful alignment. The students also picked up on
the high-reliability soldering.

The military version of the HP-8640B you showed in your video clip has an
annoying drift that makes the uninitiated wonder whether they have done
their alignment properly. Instead, when I started teaching these classes, I
used a Marconi TF-144H whose drift was negligible; then the tech college
bought an Element-14 synthesised RF sig gen - also no detectable drift. I
think HP was aware of the drift issue because I have a civilian model of the
HP-8640B that has frequency lock. And when I compare my civilian (freq lock
OFF) and military models, they both drift at the same rate. Design issue?

Dr Drake got around the receiver drift problem with specially-selected
capacitors in the local oscillator. Such sets, as I recall, have a circled S
stencilled on the front - S for stablised? Perhaps Gordon Eliot White can
confirm.

Cheers es 73 de Brian, VK2GCE

On Wednesday, 26 February 2020 4:39 AM, Ken asked:

I assume many of you have seen this?

https://www.youtube.com/watch?v=vlz83QXM66A

Ken W7EKB