6ag7 transmitter


Back to Contents A Home-made "Agent Radio". The author used a 'junker' T transmitter to build an experimental agent radio. A case officer could use such a transmitter to communicate with nearby agents, without the need to equip the agents with a shortwave radio. A BCB radio can be kept in an agent's apartment without arousing any suspicions, and without the agent needing to hide a clandestine radio. It can be operated from the standard RP-1 or RP-2 power supplies.

Since the signal is within the standard broadcast band, it would be easy for an adversary to overlook the signal, especially at night when many DX signals may be present. Or, the frequency can be chosen to be very close to a strong local station this is called "snuggling". The transmitter operates with crystal control from about KC, with a CW power input of about 8 watts.

The construction of the transmitter uses many components of the T The important changes are as follows:. The RF portion of the transmitter is a single tube. A 6AG7 is used instead of the 6AC7, to allow greater power input. The oscillator configuration is the same as the original, except that there is no longer a cathode resistor, and the plate load resistor is reduced.

The 2E26 is now used as a plate modulator for the 6AG7. The modulator tube is configured as a 'series voltage regulator', like a DC power supply regulator, except that it's output voltage is controlled by an audio signal.

This approach is simple and effective at relatively low power levels, and avoids the weight and expense of a modulation transformer. The oscillator tank was modified to operate in the upper portion of the AM band. A new tank coil was wound by hand, and an extra 47pf added to the tuning cap.

The antenna current indicator was modified to be more sensitive at lower power levels. A microphone and speech amplifier was added to drive the modulator. The microphone is a hearing-aid type earphone element. Click here to view the schematic of the transmitter. The front panel of the BCB transmitter. The toggle switch on the right selects AM or CW. The mic is permanently attached.

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A view of the chassis. In the foreground is the tank coil and the pi-net tuning cap. The 6AG7 is under the tank coil. At the top is the speech amp sub-chassis, with 3 unused tube sockets. Another view of the chassis. The 2E26 is visible in the foreground.

Next sectionVFO schematics. Kits are available for 16 bands,80, 60, 40, 30, 20, 17, 15, 12, 10, 6, 4, 2m and MHz. Satish Chandorkar 4 years ago Permalink. Readers have seen in recent posts how I developed a multi-mode beacon using the Arduino - but that was only a waypoint on the journey towards a full ham radio transceiver. Published September 30, Sprat My receiver VFO tunes from 5.

For the 7 Mhz. This hack replaces my original hack that used the AD and Pro-Mini I initially installed with a A stable VFO is one of those homebrew projects that always seems to give the most trouble. Part 1 Topband: Good valve homebrew rig. Speech amp is PP 45's. The receiver is a high dynamic range design inspired by Rick Campbell's R2. Topband: Good valve homebrew rig. Re-calibrate if the bottom of the 80m CW band falls out of range, if needed i.

Frequency Reference. It's something that might be integrated into any number of different devices. What is Homebrew Pto Vfo. It has pi network output for easy matching instead of link coupling. The article has charts and calculations to derive component values for The circuit for the new dual range VFO Not shown on the VFO diagram is a 14 db attenuator to reduce the output to dBm, the required input into the HFO mixer.

The kit uses a high-quality double-sided PCB with silk-screen, solder-mask and through-hole plating. Power supply missing. We would like to thank our customers for a great year and wish everyone a happy, healthy and With the 10 meter band starting to open, all those with the Atlas X might try this.

In a happy accident, I had ordered one of these kits several weeks ago before I found out about this mod. I have no idea how stable it is at 6 meters. I built one up and found a few minotr errors I had made in some dimensions, but the boards still worked fine.

The workmanship is very nice and I hope to have it up and running soon. A pair of thick brass washers are soldered onto the front and rear panels. June Battery Monitor project updated and finalised. This simple Hartley circuit ex- hibits less than Hz warm-up drift, with about half of that within one minute after turn-on.The tri-tet triode-tetrode, also commonly spelled tritet oscillator circuit Figure 1 was announced in James Lamb, W1CEI, "A More Stable Crystal Oscillator of High Harmonic Output," QSTJunepages 30—32, as an improved means of generating radiofrequency RF power steven dux reddit harmonics multiples of the frequency of an oscillating piezoelectric frequency-control crystal.

Misunderstood and misused, it went on to be reviled as a temperamental crystal destroyer. This page discusses the tri-tet's genesis, characteristics, and adjustment, and shows how the tri-tet, properly used, is nonetheless an excellent means of achieving good keying and high power output in a one-stage radio transmitter. Many amateurs who wish to use crystal control on the 7- and mc. In the course of experimenting with many types of doubling equipment I have arrived at the circuit arrangement of Figure 1, which gives very good results with a minimum of parts.

Either a 46 or 47 can be used in this circuit. The oscillator tank is placed in the screen grid of the '47 or outer grid of the 46, and this much of the circuit performs just like any other crystal oscillator.

The tank in the plate circuit is tuned to twice the crystal frequency, and is adjusted for the dip in plate current in just the same way as the ordinary amplifier or doubler. The values are not critical. At the voltages shown an output of about 5 watts is obtainable on 7 mc. In actual operation the '47 is superior to the With the '47 the plate current is 18 to 20 milliamperes, with an r. The output is the same in both cases.

If the voltage applied to the screen grid is too great the grid will overheat, and when this happens the circuit will not start up again after the power has once been turned off. Using this circuit and a second doubler of the ordinary type with a 46 tube, the output on 14 mc.

This results using the oscillator as a quadrupler have not been so good, since the output is only sufficient to excite a 46 tube to about 5 watts output.

For 3. W9BRD comments: Two factors likely played a role in the superiority of the 47 over the 46 in Durkin's circuit. The tri-tet's genesis as an electron-coupled crystal oscillator. Electron-coupled oscillator basics and value J. Durkin, W2DHM, "Combined Oscillator and Doubler," For the Experimenter, QSTDecemberpages 40—41 [see sidebar] that a prefigured the tri-tet idea accurately by using a tuned-near-the-crystal-frequency tank circuit in the screen of a 47 power pentode or the second grid of a 46 dual-grid power tube with a second tank in the plate circuit tuned to a harmonic, and b Lamb did not explicitly credit in his introductory and any later article.

Multiple forms of the tri-tet. The underlying genius of the electron-coupled oscillator was the discovery that because the screen of a tetrode or pentode tube operates at a positive voltage relative to the tube's control grid and is electronically downstream from the control grid, the screen more accurately called the accelerator grid in an audio power pentode or audio beam-power tube because its intended function is electron acceleration rather than electrostatic grid-plate shielding can serve as an oscillator anode.

This allows the plate of such a tube to be used to couple output from the cathode-grid-screen-triode oscillator through the tube's cathode-to-plate electron stream such that the plate plays or may play, as in many implementations experimentation may reveal that the plate circuit provides more feedback than imagined a relatively small role in providing feedback to start and sustain oscillation.

That early electron-coupled crystal oscillators included a tuned-circuit in the anode return of the cathode-grid-screen-triode oscillator and that Jim Lamb named his particular implementation of that approach tri-tet delayed more general understanding that every oscillator circuit that operates by means of an embedded cathode-grid-screen-triode oscillator is a tri-tet whether the oscillator anode is tuned or untuned aperiodic.

The classical Lamb tri-tet, and the Durkin tuned-screen oscillator that should rightfully be credited with having introduced the electron-coupled crystal oscillator to radio amateurs, are tuned-anode tri-tets. The later "grid-plate" circuit, the embedded oscillator in which is an aperiodic Colpitts arrangement, and the "modified Pierce" circuit, the embedded oscillator in which is an aperiodic Pierce arrangement, are untuned-anode or aperiodic-anode tri-tet oscillators.

All are triode-tetrode oscillators in the sense that Lamb described for his particular implementation; all, therefore, are "tri-tets". Early tri-tet implementations. This section introduces my theory that the Depression-era trick of bending one plate of the variable cathode-tuning capacitor so the capacitor would double hotunan dinki a switch between the tri-tet and tuned-plate, crystal-grid TPXG configurations, in conjunction with making the cathode tank tunable, was fundamental to the circuit's reputation as a crystal cracker.Right away one can see that a homebrew direct conversion 10 meter receiver is difficult because it needs a stable vfo that will tune 28 to mhz.

Schematic May before refurbishment. Upon investigation, I found that the library of rotary encoders I'm using has been updated. Then in a neat tidy place I added battery case for nicads. VFO voltage regulation that is an issue in itself as the lack of adequate voltage regulation results in frequency drift. Write-up of that project to follow as it progresses.

Thanks to you it is working fine and of great use to me as a general purpose VFO. O VFO Colpitts.

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Built-in Mic Compressor. Their inspiration has given me the courage to begin and successfully complete several projects. An exploration of all things HAM radio - homebrew transceivers, antennas, test equipment, projects, on the air and more.

I like to be able build things up in a weekend and then play with it. Well, I ran into a road block this afternoon that took some time to sort out. Re-calibrate if the bottom of the 80m CW band falls out of range, if needed i. I have hacked the example program below, it sets the Si to a default frequency of Consult the rig circuit diagram to determine the appropriate connections.

However, in a direct- conversion receiver, this dBm of LO power appearing on the RF port equates to a fairly strong signal still! The first app is an Antenna Analyzer. I'm sure there are many more.

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Sub-mini valve VFO. This simple Hartley circuit ex- hibits less than Hz warm-up drift, with about half of that within one minute after turn-on. Kits are available for 16 bands,80, 60, 40, 30, 20, 17, 15, 12, 10, 6, 4, 2m and MHz. VCO cover only khz to 12Mhz. I was surfing the net and found a reference to an unusual low phase. We started the journey with my homebrew version of the Arduino - the "Wotduino" and then wrote code to make the Wotduino work as a Keyer.

Some of the pages are in other languages, particularly German. Weight : 3. Chirp free on xtal or VFO. How to organize a homebrew Only in portuguese. Based on 'theladderline. Performance is a bit more ordinary with unslightly spurious at dBc typical on a wide span of MHz. Part of the radio collection of Emilio Focosi.I'd really like to be able to list two dozen, or perhaps at least 10 completed projects on this page. Unfortunately I rarely seem to complete, or even start, most of what I envisage.

The items detailed on this page are those projects which did get completed to a level where they work well enough to keep them intact. There are features on all I'd like to improve but at least these projects did get to completion, rather than never getting past the thinking or building stages. I have several more thermionic projects on the shelves and even more in my head waiting for some time to develop them. Hopefully this page will be added to over time; that's partly what it's about.

The projects detailed here are described further down the page and linked from the list below. The Hartley transmitter is not enclosed - this approach should be used with caution for obvious safety reasons. Please read the comments on safety and the site disclaimer here if you are tempted to try anything like this.

I have made a number 'lash ups', test set-ups and also projects that did not work well enough to keep. I recycle the parts used in all of these and sometimes write them up for this site. You can see these experiments detailed here.

As a background task I've been building quite an ambitious project from scratch, a 'forty meter' 7. This project has its own dedicated page here. This design, which I called the "TR6C4", switches a single 6C4 triode between transmit and receive duty to make a complete transceiver. The fourth pole switches the hot side of the tank circuit as required. The receiver configuration is a DC controlled "Hartley" regenerative detector using a cathode tap on the inductor with Hi-Z phones for the anode load.

The transmitter is crystal controlled "grid-plate" I'd call it a Colpitts configuration with the tank circuit in parallel with the valve shunt fed and an RFC in the triode's anode circuit. These are pretty much the same figures I got whilst breadboarding. The tuning range is [into a 50 Ohm attenuator and sig gen] is which is ideal.

On my antenna it is affected by the resonance or lack of it of the antenna but seems to be able to cover a similar range, perhaps offset by some amount depending on where the antenna is tuned. The unit requires 6. The transmit output is approx mW.

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There is no slow motion drive but the tuning rate seems ok. A trimmer capacitor is switched in during receive and has been set so the "dip" in anode current at resonance when transmitting corresponds to the corresponding receive frequency more or less. After calling the tuning knob is moved a little either side of the best dip position during reception to check for callers.

I can hear people on and aroundthe QRP calling frequency here. I don't doubt this rig is capable of some contacts but it's going to need some patience :. I have not yet produced a combined schematic showing the switching but the transmitter and receiver circuits used are shown individually: receiver and transmitter.

This amplifier uses a single beam tetrode in the "Single Ended" Class A audio amplifier configuration. Up to 4 watts of audio can be produced before distortion becomes evident. The output stage uses a switch adjustable self bias arrangement where a cathode decoupling capacitor can be switched in or out of the circuit together with a choice of two resistors giving either 35 or 45 mA standing current. I was hoping for an undistorted 5 watt RMS output with a 15 or 20 watt power dissipation by the but I initially struggled to get more than a couple of watts without distortion from my chosen HT voltage of around volts.

I suspect this voltage is too low compared with the V screen voltage for the tube to operate linearly.The Collins PTO permeability tuned oscillator exciters give you not only the flexibility and convenience of variable frequency, but also the accurate calibration and high stability inherent in the Collins 70E-8A PTO.

These units provide a precision frequency control usually found only in laboratory instruments. Yet they are built for continous operation under all normal fluctuations in operating conditions.

The slide rule dial roughly indicates operating frequency, while the vernier dial provides a direct reading in kilocycles. There are no reference charts or curves to interpolate. Accuracy and stability are so high as to be surprising to one who has not previously operated Collins PTO equipment.

Actual coverage of the PTO is from kc to kc. Sixteen complete turns of the vernier dial are required to cover this kc range.

The B was first designed as a veratile, band-switching, self-powered exciter unit. The result of repeated tests was so gratifying that it was decided to offer the B in two forms. The first, the B-1, has a link circuit output to work into a final of higher power. Except for their output circuits, the B-1 and the B-3 are indentical. The extraordinarily accurate and stable B-3 low power transmitter will find many uses around any shack. It makes a highly satisfying standby transmitter, is a natural for spot frequency network, and is the answer for emergency work due to its low power source requirements.

Also, it is unexcelled for the beginner in ham radio. At a later date, when more power is called for, he has only to add the final amplifier stage. The multipliers are gang tuned and imploy bandswitching. Plug-in coils are utilized in the 2E26 plate circuit.

Output coupling is by means of a link on the plate tank coil. Keying is accomplished by applying blocking bias to the grid circuit of multiplier stages.

A keying filter is included, to remove any clicks. Protective bias is provided for keying purposes. Voltage regualtion is applied to the oscillator in order to maintain the excellent characteristics at higher frequencies. The keyer circuit also includes a side tone oscillator which is used as a CW keying monitor. The key jack is on the rear of the chassis. Condenser tuning is utilized in the multiplier stages. Trimming is accomplished by varying the position of a powdered iron core in each coil, and by adjusting ceramic padder condensers.

All trimmers are adjusted from the top of the chassis. OFF — M. In the M. TEST position plate voltage is applied to the oscillator and buffer stages. Thus, with the meter switch in the GRID position, the frequency can be set and the multipliers tuned. The SEND position applies plate voltage to all tubes. The receiver disabling circuit operates on the SEND position. The receiver muting circuit allows fast, quiet CW break-in operation with the 75A-1 receiver, provided separate antennas are used.

Power circuits in both the transmitter and the exciter can be interconnected so that the exciter power ON-OFF switch will control the entire equipment. In the SEND position, the exciter function switch connects the ground circuits of the exciter power supplies. This method has the advantage that the exciter function switch can be set to the SEND position for tuning purposes, yet only a single control is needed for sending and receiving.We previously featured his steam powered transmitterwhich appeared in Popular Electronics in A number of his projects appeared in PE and other magazines, and the one showed here appeared in Popular Electronics 50 years ago this month, October It was a transmitter for the novice which put out a very respectable 65 watts on 80 and 40 meters.

The version had used a 6W6 tube to put out about 25 watts, along with a 5Y3 rectifier in the power supply. Tuning was accomplished by the simple expedient of tuning the pi network for maximum brightness of the pilot delete kiya hua number kaise wapas laye. Another pilot lamp was provided for monitoring the current to the crystal, since too much current could fracture it.

Cathode keying was used, but since the would mean as much as volts across the key, a 6 volt relay was used for safety. The built-in power supply used a semiconductor bridge rectifier. Smith recommended a full-size dipole antenna for the transmitter, rather than trying to use it with a random wire or multi-band antenna.

He notes that the pi network should be adequate for keeping harmonics to a minimum. However, he also advises that if TVI is a problem, a low-pass filter in line with the antenna is in order. He reported that on the air, he worked numerous stations throughout the U. In little ranch corgis to writing articles, Hartland Smith was the proprietor of Hart Industries, which produced a number of kits and a few wired setsincluding the Hart The Popular Electronics article included the address for Hart Industries for the kit, which included the pre-punched chassis.

Another Hart Industries kit was the similarly named Hart from Even though the basic circuit was quite different from the PE transmitter it used a 6AG7 oscillator and finalit did have one common design feature, namely, the use of the relay for keying. The model had an interesting twist, in that a DPST relay was used, keying the oscillator and amplifier almost simultaneously.

The result was that chirp was greatly reduced. The Hart does not use cathode keying. To change the circuit to use cathode keying, connect the cathode end of the grid resistor to common. Your email address will not be published. QST photo. Leave a Reply Cancel reply Your email address will not be published.

After using the 6CL6 One Tube Transmitter and the B amplifier on the air for several years, I decided that it would be great to have VFO control. A Brand New JAN (Joint Army Navy) 6AG7 Vacuum Tube If we also want to use the amplifier by itself as a QRP transmitter, more output, say at least 2.

40m 6AG7/6L6 CW Transmitter. This little winner uses a 6AG7 crystal madeline colbert to drive a 6L6 final on 40 meter CW. Power output is 8 Watts. I've built many transmitters over the years, but this one was definitely the most fun! It uses a 6AG7 crystal oscillator to drive an final. It's a nice little transmitter and will be a good companion to a 6SNSNV6 regenerative receiver that I plan to build into a very nice Bud Box containing a.

6AG7 Osc/Driver? (1/3) > >>. wb6kwt: I'm working to re-create a transmitter I first build in the mid 60's, it's from the ARRL handbook. The 6AG7 was, in my opinion, the best crystal oscillator tube ever made!

Using it in the Colpitts circuit, which the ARRL kept referring to as. bedenica.eu › qst-model-atship-wtlbs-specifications-ranee. construction. Here Is a major Heathkit addition to the Ham radio field, theAT-1 Transmitter Kit, Incorporarlng many desirable designfeatures at the lowest. VK1SV 6AG7/ transmitter for kHz ( m).

A new band is about to be released to amateur radio operators around the world: kHz to kHz. Here is a General Electric 6AG7, a classic! Many hams used these after World War 2 for small transmitter projects. New in the box! Don found it quite challenging to build radio transmitters from scratch; experience building a watt transmitter using five 6AG7's mounted to the. In a 6AG7 - transmitter I posted, the 6AG7 can provide more drive than Many homebrew and manufactured transmitters used this idea.

It was an updated version of the author's “Hart 25” transmitter which from the PE transmitter (it used a 6AG7 oscillator and final). A Home-made "Agent Radio · The RF portion of the transmitter is a single tube. · The 2E26 is now used as a plate modulator for the 6AG7. · The oscillator tank was. I was waiting for someone to mention the best oscillator tube ever made!

Thanks Tom. Long live the 6AG7! And of course Norm knew exactly what tube I was. KNIGHT T50 Transmitter Complete Primo Tube Set 6AGU4 Amplifier/Receiver plate current) power amp tubes + all other transmitter tubes Remember to. Many times the beginner or novice transmitter of the early 50s was some sort of single tube crystal oscillator running 5 to 10 watts. I chose a 6AG7 crystal. A return to yesteryear with a 5 W AM transmitter.

and the transmitter. 6AG7. Due to the “electron-coupling,” any changes in the load have very lit. Transmitter / Receiver Schematics and Parts Lists ARRL Handbook (34th A One-Tube Two-Band Transmitter for the Novice (6AG7) Page ; Schematic.