Collins 55G-1 LF Tuner ( Advanced Optics Kit) Fully Built, in Excellent Condition

This Collins 55G-1 LF Tuner ( Advanced Optics Kit) Fully is Built, and in Excellent Condition.

The 55G-1 Low Frequency Tuner Reproduction is actually a Kit that was sold by Advanced Optics Ltd in England, in collaboration with the Collins Radio Association.

My Friend David Curry who is renown for his work making Mechanical Filters for the Collins 75A-4,  purchased this 55G-1 as a kit on Ebay for $1,200.00.

 He assembled and aligned the kit and this unit performers better than the original in part because there is no AC power supply to introduce noise, just a standard 9 volt battery that lasts a long time. Dave does extensive work in the low frequency bands so he is very familiar with pre selector performance.

He assembled the unit and aligned it using a network analyzer so the proper upper and lower frequency limits were accurate and the double-tuned  band pass response on the AM broadcast band were at the narrowest 8Kc at 600kHz and 10kHz at 2 MHz.

The skirts are steep and provide excellent rejection of nearby AM stations. 

The LF section is a single peak response and works properly. Average bandwidth is +/- 3dB: 1.5 kHz. 

This product uses a 9 Volt battery for power which provide noise free power to a one-stage JFET amplifier that only draws 4mA.  Additionally, the battery provides no AC hum or noise to the LF/MF preamplifier. I would prefer this for any serious NDB or LF listening over a AC related circuit.

 Talking with Dave about this unit, he told me he improved the wiring over the original 55G-1s by using coax for some of the crucial runs which also help performance.

 It appears to be in an original Collins Cabinet which is the same as a 312B-3 speaker cabinet.

 From the front it look just like the original 55G-1 as it has the correct front panel and controls.

 I tested the 55G-1 with the 51S-1 offered, and it appears to be working even better than the original 55G-1 which only works on the two low frequency bands, it does not switch in on all the other bands.

 An original 55G-1 sells for over $2000.00 these days so this is a great price.

The Collins 55G-1 LF/MF pre selector was designed for the 51S-1.

It provides enhanced reception in the 200 kHz to 2 MHz range and features a 4 ohm 5x7 inch speaker.

It features a three position band switch:  200-600, 600-2000 kHz and by-pass.