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Topic: Tuned radio frequency receiver

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	History of Radio
		V1 is a tetrode amplifier that amplifies the tuned signal from the aerial.
		When a station is tuned in, the oscillator frequency is also adjusted so that the difference in frequency between it and the tuned frequency is always the same.
		V1a is the mixer, its output is tuned to the I.F. frequency by L2 and C3.
	www.localhistory.scit.wlv.ac.uk /Museum/Engineering/Electronics/history/valvedetails.htm (1895 words)

	5
		The Tuned Radio-Frequency Receiver was in use in the 1920’s after several years of frustration with the crystal radio set, and before Armstrong and others developed the superhetrodyne radio in the mid 1930’s.
		The basic principle of TRF receivers was that all RF stages needed to be simultaneously tuned to the received frequency before detection and subsequent amplification of the audio signal.
		As the tuning dials are moved towards higher frequencies, it is necessary to reduce the reaction setting to maintain stability.
	komar.cs.stthomas.edu /qm425/02f/Seeger1.htm (1235 words)

	radio. The Columbia Encyclopedia, Sixth Edition. 2001-05
		A radio wave acts as a carrier of information-bearing signals; the information may be encoded directly on the wave by periodically interrupting its transmission (as in dot-and-dash telegraphy) or impressed on it by a process called modulation.
		In an AM transmission the carrier wave is constant in frequency and varies in amplitude (strength) according to the sounds present at the microphone; in FM the carrier is constant in amplitude and varies in frequency.
		In both radio and television receivers, once the basic signals have been separated from the carrier wave they are fed to a loudspeaker or a display device (usually a cathode-ray tube), where they are converted into sound and visual images, respectively.
	www.bartleby.com /65/ra/radio.html (1173 words)

	Tuned radio frequency receiver - Wikipedia, the free encyclopedia
		A radio receiver comprised of several tuned radio-frequency amplifiers followed by circuits to detect and amplify the audio signal.
		It was replaced by the Superheterodyne receiver invented by Edwin Armstrong.
		The TRF receiver was patented in 1916 by Ernst Alexanderson.
	en.wikipedia.org /wiki/Tuned_radio_frequency_receiver (255 words)

	Audio Ideas Guide: High End Audio Articles and Columns - Analog Radio's Swan Song
		Radio was born, if only as a method of communication that consisted of dots and dashes.
		Before super regeneration, a local radio station was restricted to a small geographic audience, and the format had practical limits which made it a nighttime hobby for the few listeners that were starting to embrace the format.
		The enthusiast had to tune each stage, but skilled operators enjoyed zeroing in on a given frequency, and it can't be disputed that a properly set up TRF (tuned radio frequency) receiver had a wider bandwidth potential than Armstrong's system.
	www.audio-ideas.com /techupdate/radio.html (1491 words)

	TSCM Handbook - Chapter 5
		Perhaps the simplest way to study receiver technology is to keep this in mind: whatever is done to change the modulating signal at the transmitter, it must be undone at the receiver.
		In mixing an incoming radio signal with the local oscillator signal, there will be present at the output the original two signals plus the sum and the difference signals of the two, plus harmonics of these sum and difference signals.
		Some receivers are "double-superhetrodyne", and this means that the output from the first I.F. of 10.7 MHz is hetrodyned with a second (fixed) local oscillator to produce a second I.F. for further amplification.
	www.dbugman.com /handbook/tscmh5.html (2275 words)

	Chapter 4: Radio
		The heart of the radio is a special 10 transistor integrated circuit in a tiny three-legged bit of plastic.
		The bowl is the positive wire, and connects to the radio where the red wire from the battery holder went.
		The tuning knob is a plastic soda straw glued to the brass shaft of the variable capacitor, and exitting out of a hole drilled in the back of the box.
	www.scitoys.com /scitoys/scitoys/radio/three_penny/three_penny.html (2772 words)

	Radio receiver design - Wikipedia, the free encyclopedia
		In the Direct conversion receiver the signals from the aerial pass through a band pass filter, and an amplifier before reaching a non-linear mixer where they are mixed with a signal from a local oscillator which is tuned to the carrier wave frequency of an AM or SSB transmitter.
		For CW morse the local oscillator is tuned to a frequency slightly different to that of the transmitter to make the received signal audible.
		To make a good FM receiver a large number of RF amps which are driven into limiting are required to create a receiver which can take advantage of the capture effect, one of the biggest advantages of FM.
	en.wikipedia.org /wiki/Radio_receiver_design (597 words)

	Transmitter & Receiver Architectures:
		whose frequency is well suited to the propagation environment, conforms to the licensed operating bands, and is sufficiently stable to allow detection by a tuned receiver in the presence of interference.
		The simplest of all receivers is the tuned radio frequency (TRF) receiver.
		Because the input of the receiver is exposed to strong adjacent and out-of-band signals, linearity and intermodulation performance of the front-end amplifier and mixer stages must be carefully considered.
	www.avren.com /Courses/TX_RX_Architectures_plain.htm (5128 words)

	Radio Receiver design basics
		It is a complete electronic tutorial ranging from the very basics of radio design to the more sophisticated configurations used in short wave radio, ham radio or hobby electronics as a general purpose radio receiver.
		The T.R.F. (tuned radio frequency) receiver was among the first designs available in the early days when means of amplification by valves became available.
		A superhetrodyne receiver works on the principle the receiver has a local oscillator called a variable frequency oscillator or V.F.O. This is a bit like having a little transmitter located within the receiver.
	my.integritynet.com.au /purdic/am_rec.htm (1390 words)

	United States Patent: 6,469,582 (Site not responding. Last check: 2007-11-03)
		The frequency selection circuit includes a first phase shifter that, in one aspect, is formed by a first capacitor coupled between the first port and a reference voltage.
		The frequency selection circuit further includes a second phase shifter, which may be formed from a capacitor coupled between the output of the second amplifier and a reference voltage.
		The radio frequency signals are typically amplified in a radio frequency amplifier RF AMP 156 and are routed to the antenna 122 for transmission.
	web.engr.oregonstate.edu /~flf/6469582.html (4361 words)

	Introduction to Radio Equipment - Chapter 18
		You TUNE your receiver by adjusting the variable condensers until the RESONANT FREQUENCY of tank circuits in the receiver is the same as the FREQUENCY of the station you wish to hear.
		The condenser that tunes the oscillator is connected, or ganged, to the SAME shaft that tunes the r.f.
		This is done by opening the TUNING condensers to their widest mesh at the high end of the frequency band, and then adjusting the trimmer controls until the noise level is maximum.
	www.hnsa.org /doc/radio/chap18.htm (3699 words)

	Old Radio (Site not responding. Last check: 2007-11-03)
		The set is a four-tube, tuned-radio-frequency receiver with an untuned stage of radio-frequency coupled to a tuned detector stage with regeneration.
		Only one coil and one tuning condenser are required, instead of a ganged condenser and a matched pair of antenna and radio frequency coils.
		The radio frequency portion of the set remains the same as in the previous article, except that an audio stage is resistance-coupled.
	home.gwi.net /~jdebell/oldradio/orarticle.htm (148 words)

	Arnie Coro's Dxers Unlimited, shortwave radio, science and technology news (Site not responding. Last check: 2007-11-03)
		The TRF or Tuned Radio Frequency receiver was one of the very first circuits used during the early years of radio, but today you won't find many TRF radios except perhaps in some very specific short range applications like garage door openers and electronic lock systems for cars.
		Radio experimenters still homebrew TRF receivers, and let me tell you that they can deliver excellent audio quality, but their main drawback is lack of selectivity.
		In the old days, TRF or tuned radio frequency receivers used several vacuum tube stages of amplification, each with its own tuned circuit, and those who used those radios had to peak each individual stage by carefully moving the variable capacitors back and forth until they obtained the maximum signal output.
	www.radiohc.org /Distributions/Dxers/scripts/00-1024.html (1517 words)

	Communications Trainers
		Varactor (voltage controlled diode) tuning is used and all but one tuning coil are a fixed etched patterns on the reverse side of the printed circuit board.
		All incidental circuit components of the FM receiver are mounted on the underside of the board.
		Single-sideband communication with reduced frequency band width requirements and greater efficiency are being put into increasing use, in an effort to provide more effective use of the available radio communication frequency spectrum.
	home.att.net /~cat1/cat36.htm (595 words)

	MW REFLEX RECEIVER by SM0VPO
		The receiver may also be extended into the HF band and used with a converter to receive air traffic between 115 and 125MHz.
		The 1mH RF choke prevents the amplified radio frequency signal from passing to the output circuit, the RF is only passed through the 1nf capacitor to the two germanium diodes, where it is rectified to recover the audio signal.
		It is unusual for a TRF receiver to have sufficient sensitivity to do-away with an external antenna.
	web.telia.com /~u85920178/rx/reflex_rx.htm (1127 words)

	Radio Receivers (Site not responding. Last check: 2007-11-03)
		their tuning condensers are connected/ganged mechanically in such a way that when we tune the variable capacitor in the RF section, the variable capacitor in the local oscillator also changes its value, it 'tracks' the frequency to which the 'Aerial Circuit' is tuned and remain seperated from the tuned frequency by 455 kHz up.
		Similarly, when a receiver is tuned to particular signal the output level can vary widely if the input signal strength fluctuates as a result of fading and adjustments of the volume control has to be done.
		The pocket radio set should also be tuned to a frequency near to the frequency in which the ham transmission is received.
	www.qsl.net /vu2msy/receiver.htm (2227 words)

	Crystal Radios "Stay Tuned" Crystal Sets
		By loosely coupling the output of a small signal generator and tuning it to the frequency of the LW crystal set, many more LW beacons were heard.
		Tuning a BFO to the carrier of a weak DX signal raises the voltage of the signal to a region of
		Tune to a known station and 'count channels' to either side by noting the ascending/descending pitch squeal to the next zero beat.
	www.crystalradio.net /crystalsets/bfo/index.shtml (1879 words)

	Antique Phonographs & Radios
		It was a "Tuned Radio Frequency" (T.R.F.) type, typical for the era and a very simple design.
		The radio used "01A" tubes and because they were low-amplification triodes, several stages were normally required.
		When the station is tuned in, increase or decrease both Detector and Amplifier until you have obtained the desired volume.
	gvtc.com /~k4oce/antique_phonographs__radios.htm (1028 words)

	Electronics and Radio Today: Radio
		Radio broadcasting is one of the most obvious forms of radio transmission.
		Today radio is used for many forms of communication from long distance satellite communications to the personal cell phones that are widely used.
		The radio antenna is an essential element for any radio system be it a broadcast receiver, a long distance radio transmitter or a small Wi-Fi module.
	www.electronics-radio.com /articles/radio/index.php (184 words)

	Phase-Locked Loop Tutorial, PLL
		To counteract this frequency drift, the frequency of the local oscillator was compared with the input by a phase detector so that a correction voltage would be generated and fed back to the local oscillator, thus keeping it on frequency.
		For example, radio telemetry data from satellites used narrow-band, phase-locked loop receivers to recover low-level signals in the presence of noise.
		The phase detector is a device that compares two input frequencies, generating an output that is a measure of their phase difference (if, for example, they differ in frequency, it gives a periodic output at the difference frequency).
	www.uoguelph.ca /~antoon/gadgets/pll/pll.html (3369 words)

	eEngineer -- Radio Frequency Interference (RFI)
		This is defined as undesired signals with frequency components which fall within or near the receiver’s RF passband and are translated outside of the IF passband via the mixer stage.
		The undesired emissions which are translated outside of the IF passband may still pass through the remaining receiver stages, if at high enough levels to survive the out-of-passband attenuation.
		This is defined as undesired signals with frequency components that are significantly removed from the receiver’s RF passband.
	www.radioing.com /eengineer/rfi.html (931 words)

	Regenerative TRF Receiver (Site not responding. Last check: 2007-11-03)
		The A.F. output from the receiver is connected to the Mic.
		Tune in the AM station with the main tuning control.
		In the valve (tube) era, regenerative receivers were notorious for causing interference.
	homepage.eircom.net /~ei9gq/regen.html (374 words)

	Dialogue on Radio Telescope Receivers
		I'm somewhat familiar with TRF receivers from the past "good old days" and I guess I was expecting to see a picture of a box somewhere with a dial, volume control, and tuning knob on it.
		Once the detector and low-pass filter in the post-detection part of the receiver have removed the modulated signal from the composites waveform (consisting of RF carrier plus audio modulation) the audio modulation is then passed to an (audio) amplfier and then to a speaker.
		In fact, a receiver with a label "I am a TPR" with a bandwidth of 10 or 15 kHz or so, is tuned to your favorite AM station, it would produce exactly the same output at its detector as does the AM receiver at its detector.
	www.ap.stmarys.ca /~lonc/talk.html (3271 words)

	Antique Radio Classified
		The idea for this radio design came to Benjamin Abrams, president of Emerson, while looking at a clock or rather a clock case, handsomely styled, as style was understood in those days.
		For some reason the midget sets -- in those days, cathedral and tombstone receivers were considered midget sets -- had failed to hold their own on the market and had lost public favor.
		The idea of squeezing a radio chassis, along with the tubes, speaker and everything else into a case this small was preposterous, to say the least.
	www.antiqueradio.com /Dec06_Arnold_Emerson25.html (1247 words)

	[No title]
		One way to construct a radio is to use a series of tube amplifiers, each with a tuned circuit in its plate lead.
		A radio using these amplifiers would have to have several of them connected one after the other and to receive a particular station all of the tuned circuits would have to be set to the frequency of that station.
		The reason the 1920 radio had 7 tuners was because the tubes of that time had very low gain and it took a lot of them to get enough gain to bring the radio signal up to a high enough level for a crystal or tube detector to recover the audio.
	www.angelfire.com /electronic/funwithtubes/TRF.html (1061 words)

	[No title]
		Finally, the Radio Act of 1927 gave the FRC necessary power to regulate the technical operations of stations.
		Early radio broadcasting technology was primitive but gradually improved with radio's commercial success.
		With a tuned radio frequency receiver, each stage of amplification had to be tuned, then retuned to the desired station.
	ieee.cincinnati.fuse.net /reiman/02_1994.html (470 words)

	[No title]
		\par {\listtext\pard\plain\ltrpar \rtlch\fcs1 \af0 \ltrch\fcs0 \insrsid12796759\charrsid12796759 \hich\af0\dbch\af0\loch\f0 B. \tab}Compare and contrast the super heterodyne receiver to the tuned radio frequency receiver.
		One is the desired reception frequency; the other is called the }{\rtlch\fcs1 \af0 \ltrch\fcs0 \b\fs24\ul\insrsid5194289 image frequency}{\rtlch\fcs1 \af0 \ltrch\fcs0 \fs24\insrsid5194289 and must be eliminated before mixing with the local oscillator.
		If this latter specification cannot be met, the input radio frequency [RF] stage must filter/suppress the undesired image frequency.
	www.usna.edu /EE/ee334/Lessons/LESSON11.doc (1541 words)

	EASY HAM BAND RCVR (Site not responding. Last check: 2007-11-03)
		Amplitude-modulated shortwave stations are tuned in with L2/C2, converted to pulsating dc ("detected") by D1, filtered via bypass capacitor C4 and converted to ac by coupling capacitor C5.
		The sum-signal is beyond the audio frequencies and therefore not usable, but the difference-signal of these is an audio frequency that is detected by D1, filtered, coupled, amplified and heard via common 8-ohm impedance headphones attached to the output end of T1.
		You can experiment with readjusting the coil windings to try receiving bands up to 20-meters, but avoid the 160-meter band: it's too close to the standard AM broadcast band and there is a (small) possibility of interfering with neighbors' reception.
	cs.okanagan.bc.ca /ve7ouc/eng/kc6wdk-mirror/receiver.html (964 words)

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