Submitted by Skywave, Nov. 5, 2012
Collins 75S-3B: top of chassis view.

I've used several Collins radios over the years but the 75S-3B isn't one of them! What follows is a summary of my researches - and is therefore provisional: i.e., read as "e.and o.e."
You may add corrections or amendments as another Comment. If you do, please notify me via the main forum. Thank you. [Skywave, Nov. 2012]

Collins 75S-3B: Dates from mid-1960s. Prices: 1964: $620; 1977: $2500.
General description: double-conversion s/het. with tunable 1st. I.F: 2955 - 3155 kHz; 2nd. I.F. 455 kHz.
Will resolve AM / SSB / CW / RTTY.
Optional filters for AM and CW / SSB.

Freq. coverage is in 200 kHz 'chunks':
3.4 - 3.6; 3.6 - 3.8; 3.8 - 4.0 MHz
7.0 - 7.2; 7.2 - 7.4 MHz
14.0 - 14.2, 14.2 - 14.4 MHz
14.8 - 15.0 MHz (WWV)
21.0 - 21.2; 21.2 - 21.4; 21.4 - 21.6 MHz
28.5 - 28.7 MHz
Any 200 kHz segment in the range 3.4 MHz - 30 MHz can be covered by inserting appropriate optional crystals (except 5.0 - 6.5 MHz). Hence the whole of the AmRad 10m. band can thus be covered.

Crystal calibrator 100 kHz
Selectable AGC time-constant.
Tuning dial resolution: 200 Hz on all bands.
Weight: 20 lbs.
Valves: 6AT6, 6AU6, 6BA6, 6BA6, 6BF5, 6DC6, 6EA8, 12AX7.
Operation from a.c. mains (230v. / 115v, 50 - 400 Hz) or external d.c. PSU.

A very popular Amateur Radio amongst the better-off AmRad fraternity! There is much written about this receiver on the Internet, including detailed restorations that have been done.

Photo. submitted by Al. (Skywave) on Nov. 4, 2012.

Another photo. of the RCA AR77E

Submitted by Al. (Skywave) on Nov. 4, 2012.

Hewlett-Packard 1741A: 100 MHz storage oscilloscope.

HP made several 'scopes in this range, so they all look very similar at a casual glance. This particular model is quite rare since it is the CRT storage version. What is unusual in this respect are the controls which are brought out as 'operator adjustables' and the slide-switch at the case rear whereby the entire 'storage function' can be disabled, thus producing a 'normal' 'scope.
One unusual and useful feature of this range of 'scopes is that the input sockets for the vertical amplifiers can be configured for an internal 50-ohm load to be switched in. (But be careful that you don't overload it!)

Maintenance issues.
By-and-large, this range of 'scopes from HP are quite reliable, but they do have a few short-comings.
1. The feet, mounted at the rear of the item: they are fabricated from some type of hard plastic (they look just like Tektronix feet, but Tek's are made of hard rubber). With time, that plastic becomes very brittle. The first you usually know about this is when you rock the 'scope back onto two feet at the rear - whilst trying to pick it up - and crack!: two feet shear off.
2. The time-base switches. With time, the internal rotary selectors become very stiff. The usual consequence is for the delayed time-base rotary knob to split internally where it meets the brass milled annulus that couples that knob to the shaft. On account of the age of this range of 'scopes, obtaining a replacement knob will be very difficult. So, prevention is better than cure: before trying the controls for rotation, take the top cover off the 'scope and squirt the switch contacts with switch cleaner: you should feel a gradual 'easing-up' of the switch knob rotation as the cleaner takes effect.
3. General construction. The internal construction does not permit for easy maintenance, but no worse than the Tek. 455 / 465 / 475 / 485 series (could anything be worse?).

Availability.
They appear on e-bay now and again. Typical prices (for a 'declared no-faults' model) is in the range £80 - £130 at time of writing, with the 200 MHz version fetching a bit more.

Marconi TF 975 Absorption Wavemeter.
A closer view.

Lawrence 07/07/2012.