It is very likely that this is due to the elimination of extraneous circuitry. One tuned stage in the oscillator. The mixer is balanced. In wide mode 5 ceramic filters are the IF path. In narrow mode the first filter is replaced by two new ones and the second and third filter get replaced by two new ones. A second mixer is needed to produce the low IF needed for digital direct decoder chip. I also reported on this demodulator in issue 24 of The Audio Critic. Pressing a button momentarily displays signal strength as a single digit.
AM covers the extended band to kHz. Inside I found what at first appeared to be a basic tuner circuit, with two RF tuned circuits in the signal path, two IF filters and kHz , and a single-tuned quadrature detector. There is no pilot cancellation or supersonic filtering. Enabling it and poking around with a scope, I discovered that the tuner scans the RF-amplifier varactor voltage over a small range whenever the tuned frequency changes.
It then uses the voltage that yielded maximum signal. I intentionally misaligned the front end and found that CCTS very effectively restored proper tuning. In addition to correcting a sloppy factory alignment, CCTS can compensate for temperature variation or component aging.
CCTS is fun to watch as it displays signal strength before and after adjustment. It takes a second or two to operate, so you can disable it when you want to tune across the band more rapidly. You can also leave it off if you don't tune weak signals. The front end has no trimmer caps or inductor slugs, but the coils are easy to deform with a plastic tool. I was surprised to find that sensitivity was dB higher than what I normally measure for most tuners.
With the s installed, HD Radio self-noise was not objectionable. I heard a little background noise on a couple of strong signals, an indication of RF intermod in my high-RF location, but it wasn't all that serious. Some high-end tuners I've tried performed a lot worse.
The kid forced to wait on you will look at you like you have Three Heads! Our contributor Scott reports: "The TX is a well-built unit with a large power supply.
The headphone output and control is very handy. It is reasonably selective for a single-bandwidth tuner and has good to very good DX capabilities for a 4-gang unit.
The AM and FM sections have rich audio. The automatic gain control of the AM section is excellent. There's a page on the TX with photos, specs and brochure excerpts with some typos on the Stereonomono website. Complete with the very latest design components and transistors, the TX provides all the requirements that the audio enthusiast demands in a tuner - and then some.
MOS-type FETs in the front-end, an IF section featuring ultra-sharp crystal filters and ICs with outstanding limiting effect provide unsurpassed capture ratio and selectivity. The wide linear dial scale works with two sensitive tuning meters for pinpoint precision, and is complemented by multipath terminals and other refined features for perfect reception.
Both AM and FM have separate output level controls. And even without an amplifier you can still listen to this unit through headphones plugged into the headphone jack. The Pioneer TX puts it all together for convenience and superb reception. Read on to learn why it's the finest component of its kind for your stereo money. The circuitry employs four gang variable capacitors. Additionally, FETs are also used in the mixing circuit, which complements the stabilized Colpitts-type mixing oscillator.
The result of these components is an image rejection ratio of 90 dB, spurious response of 95 dB and excellent interference rejection characteristics. All of these key front-end features add up to provide outstanding FM reception, even in weak signal areas, with freedom from signal overlap and noise.
The ICs provide an excellent limiting effect for stable performance, while the outstanding selectivity of the crystal filters assures sharp signal reception. The result is a constant performance unaffected by temperature, humidity or age and ideal selectivity characteristics of over 70 dB and a 1. Simply flicking the noise filter to the ON position will correct high-frequency MPX noise which is often created during reception of FM stereo broadcasts.
The large TX dial scale was specially designed to be read at a glance. The linear design is not only easy-to-read, but also brings all stations closer together for easy tuning.
The TX uses two extra-large tuning meters, a signal strength meter and a center tuning meter. This permits precision tuning for minimum noise and maximum stereo separation. Both can be set to compensate for differences in AM and FM signal strengths, so that the amplifier's master volume control does not require readjustment when the selector is switched. The TX is a handsome stereo component with stylish front panel and natural wooden case. Dimensions and styling are matched to complement other Pioneer hi-fi components to let you create an installation of systemized elegance.
The dealer informed me that this is extremely rare and makes this tuner highly sought after for high-end collectors! In the center of the main board, the two adjacent ceramic filters have been placed in sockets. The sockets will eventually hold a pair of Bill Ammons's amplified filter boards.
At the bottom left corner of the main board are new polypropylene de-emphasis caps. Not only are they better than the stock mylars, they correct the de-emphasis time constant from The top board is the audio and power supply circuits.
The supply filter caps are upgraded to Panasonic FMs and the audio couplers are now big polyprops or Panasonic FMs bypassed with. An access hatch was cut from beneath the main board so as not to have to disrupt the dial cord by removing the board for changes.
The hatch was made to be bolt-on replaceable. RFM also did a 'poor man's alignment' to this victim. That worked very successfully and much improved the sensitivity. In an attempt to adjust the centering meter, the upper and lower frequencies at which the stereo beacon would light were noted, the tuner set twixt those points and the meter centered there For anyone still reading this drivel, the TX had the right stuff for good sound.
There's a page on the TX with photos, specs and brochure excerpts on the Stereonomono website. Here's Pioneer's own description: "Pioneer's easy-to-operate high quality tuner. A compact, sensitive, practically-priced tuner. Exclusive FM IC with 5-stage limiter. MPX circuit with high-performance IC for wide separation. Large signal meter and wide linear FM dial scale for easy tuning. MPX noise filter. The TX has one IF gain stage, which gives it good sensitivity. Our contributor Bill Ammons calls it "a great performer in stock form, both in higher RF and rural environments.
The TX's circuit board is easy to access for service or mods, which can turn it into an excellent budget tuner for DXers. In stock form, it's nothing special and is difficult to modify due to its circuit board configuration. When modified with an improved IF stage, the TX is an excellent performer that easily beats my Carver TXa stock in fringe station grabbing power.
An exclusive signal strength meter coupled with the centre tuning meter and wide linear dial scale offers precise easy tuning convenience. Other features include fixed and variable output level controls, multipath output terminals and an MPX noise filter. The TX's single-bandwidth IF stage consists of 3 ceramic filters and one gain stage. The audio output is discrete. The AM section uses an HA chip.
Bill adds, "The higher Q design of the RF front end allows better operation in strong signal environments. The construction of the unit makes it very easy to service and modify. This brought the IF ceramic filter count up to 5, and added two gain stages for a total of 3. The TX has only one IF setting for FM so it's not likely to satisfy the competing desires of an audiophile-DXer as well as a KT for example might, because a filter mod to maximize selectivity in the TX will necessarily affect its audio quality.
In the KT and other dual-IF tuners, a wide-bandwidth ceramic filter may be left in the wide IF mode for great sound on local stations while narrower filters can be installed in the narrow IF mode to improve selectivity for DXing. The TX is one of the very few tuners with wide and narrow bandwidth settings for the AM band.
Our contributor Steve reports: "I replaced all of the electrolytics in a TX that I picked up quite cheap. Panasonic FCs in power supply and in 'non-critical' positions and Black Gates in the rest various series, depending upon value and position.
Also rerouted a lot of the wiring and replaced it with Cat 5e - IMHO, this tuner has been transformed. It had a very 'transistor radio' sound before, and now sounds very good. Featuring a broad range of newly-developed circuit elements, an accomplished front-end and near-perfect performance characteristics, it offers unique value and even more sensitivity and selectivity.
Its front-end section employs dual gate MOS-type FETs in the RF stage and mixing stage, coupled with a frequency linear 4-gang variable capacitor, the entire package adding up to sensitivity rated at 1. Overall, this is a first-rate unit for advanced stereo component applications. Among its features are an FM muting switch that cancels inter-station noise, an MPX noise filter for enhancing tonal quality by suppressing irritating high frequency noise in stereo broadcasts, and multipath output terminals to permit accurate antenna direction.
Output level controls for AM and FM are independently adjustable. And because output terminals of the TX are both fixed and variable, it is possible by utilizing the fixed output to direct-record from the tuner by bypassing your amplifier. Other features are equally significant. The FM dial scale is the wide linear type for precise, easy station tuning. There is a headphone output jack with an adjustable level control so that you can enjoy stereo listening with the tuner only.
And much more. A very important addition to the Pioneer line of quality stereo components. Local oscillator with buffer circuit. New high-performance large scale integrated circuits for FM IF section. Phase-linear ceramic filters in the FM IF section for excellent selectivity characteristics. FM Multipath output terminals.
Double-Action FM Muting circuit with read relay. Precise flexible signal meter. Improved AM tuner performance. Ceramic filters in the AM IF section. Headphone output jack provided. Fixed and variable output level controls.
It has 4 gangs vs. Our contributor Bill Ammons says, "In the wide mode there is one ceramic filter followed by a tuned In narrow, the signal routes through the wide filter and consists of 3 more ceramic filters and one additional tuned LC. In stock form all of the ceramic filters are kHz. The front end in my opinion works great in high-RF signal environments.
Four gangs, single RF amp. The sound is unrated at this point as it needs alignment and switch cleaning. The filters are quite easy to get to. Sensitivity is pretty good. Visit our FMtuners group for good tuner-related conversation. Permission is hereby granted to quote our text so long as proper credit is given. Pioneer Tuners Tuners are listed in alphabetical and numerical sequence by model number. Our contributor Lorne tells us that the TXII, in addition to the extra gang, has wide and narrow IF bandwidth settings, a larger chassis and a bigger circuit board.
The layout of the board is somewhat similar to the TX's, but is about a third again as large. The TXII has a different power supply board with fewer electrolytic caps and one fuse, compared to the TX's bank of four or five.
The TXII has some other interesting features, including a recording level calibration signal. Both units have a variable output option controlled by a pot operated on the faceplate. Lorne adds that the TXII has "a wide-open sound, with bags of detail and impressive bass.
Unfortunately, it can't be modified for optimal selectivity without taking it apart because of the way the circuit board is constructed and wired. The TX uses discrete transistors in its output stage no op-amps and has a smooth, powerful sound that some prefer to that of later Pioneers.
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