This is from fmtunerinfo.com
Yamaha CT-810 (1975, $285, photo) search eBay
The CT-810, the older and lesser sibling of the CT-1010, is apparently not as good a tuner as the CT-800. Our contributor Marc reports that the CT-810 is less sensitive than his top tuners but is easy to modify for better sound quality: "Stock, the sound is not bad but it is not high definition. I bypassed the volume control, replaced the power supply diodes with Schottkys and changed the lytic caps at the output with polypropylenes. These simple mods gave surprising results. The sound quality blows away a lot of tuners. The front-end first stage is made with a FET. The output stage is made with transistors, which is probably why the CT-810 has a relaxed, natural sound." Our contributor John H. says his CT-810 has "fairly nice and warm bass and good overall range. After removing the 300-ohm balun and replacing the third filter with a narrower (110 kHz) filter, the sensitivity comes much closer to my T-85 and the selectivity is also improved. The stock filters were Taiyos, and when I replaced them with newer ones I got a jump in signal strength, so they must have had pretty high insertion loss or were out of spec."
Here are some excerpts from the CT-810’s owner’s manual, courtesy of our contributor John P.:
"SPECIAL FEATURES of the CT-810 TUNER:
1. Stable and Sensitive Front End--MOS FET, four-gang wide air-gap frequency linear variable capacitor, and special transistor local oscillator give great station-getting ability, free from drift.
2. Direct Assessment of Differential Gain--This sophisticated technique, with the six low-loss, low-spurious content ceramic filters used, and a special impedance-matching phase compensation circuit, gives the CT-810 a combination of low distortion and high selectivity hitherto impossible.
3. NFB PLL MPX Section with Pilot Cancellation--Pioneered by Yamaha, this unique MPX circuit gives the full advantages of stability (from phase-locked PLL circuitry) with ultra low distortion (from full application of NFB-negative feedback), and wide flat frequency response (by completely cancelling out the 19 kHz pilot signal).
4. Optimum Tuning System (OTS)--The OTS system will take over from you the fine-tuning needed to maintain minimum distortion and maximum stereo separation, so that all FM stereo programs are heard at their best.
5. Twin-Meter FM Tuning with Signal Quality Reading--Both signal strength and center-zero FM tuning meters are provided on the CT-810, with the signal strength meter doubling as a signal quality meter on FM.
6. Standard 333 Hz Signal for Level Setting--The REC CAL setting provides a signal ideal for recording-level calibration. Like the normal tuner output, it is fully variable.
7. Twin-Level Muting--Inter-station noise and distant stations can be silenced at either of two levels of sensitivity.
8. High Blend and Provision for Dolby Adaptor--The Noise Reduction switch has a high blend position to reduce hiss noise on stereo FM stations, and a Dolby adaptor can be fitted for use with stations broadcasting Dolby-ised programs.
9. High Performance AM Section--Untuned RF stage, differential mixer, and peak detector assure the best possible reception of the crowded AM band."
Despite all these features, the CT-810 usually sells for just $40-90 on eBay, and one even went for $15 in 7/05. The high was $162 in 5/10 when two guys ran it up from $52.
