Gs35b amplifier schematic

The Ameritron AL Amplifier is in current production. Some of the nice features of this amplifier include. Re-tubing of an amplifier can be a good choice and fun tooif a tube of similar plate dissipation and operating characteristics can be found.

Considerations need to be given to filament voltage, input signal feed, biasing, tube cooling and tube mounting. Besides the cooling and mechanical issues, the following needed to be done:.

This particular AL is one of the earlier ones manufactured— The owner from whom I purchased it Jan KX2B was the original; the tube suffered some catastrophic failure many years ago, and the amplifier had been sitting around since. The original AL fan is good for 55cfm according to Ameritronso that had to go, but that left even less room.

Looking in the Grainger catalog, the Dayton 2C Blower has the motor partially set into the squirrel cage area; the CFM seems about right with about 80cfm at 0. This seemed like the right blower, but it was too big to pressurize any kind of sub-chassis.

The only orientation that worked was blowing directly towards the front panel. The challenge then became to get the air to actually blow through the tube cooler. Everything then fell into place. The single-gang box, with a metal cover plate, holds the plate choke. The rubber sheeting material was fashioned to snugly fit the tube, and slip inside the collar, and marked with a line.

I made sure that the bias was being applied to the cathode ring through the new bias choke fabricated with wire scramble wound on a ferrite rod. Note in the picture the large blue capacitor to bypass any RF making it back to the bias board. The new filament transformer was located just ahead of the plate transformer, and above the location of the original filament transformer.

Electrolytic capacitors, if not used for long periods of time, can lose their voltage rating. I left it there for about an hour, sniffing to make sure nothing was amiss the bleeder resistors are still too cold to make any smell at that voltage. Nothing unusual happened, but the bleeder resistors started to burn off whatever dust they had on them — just like turning on the furnace for the first time in a heating season.

After leaving the unit on at maximum voltage for about 15 minutes, I turned it off, removed the variac, replace the cover on the amplifier. After letting the amplifier turn on a warm up for 2 minutes, I keyed it.

Emboldened, I slowly brought drive up to and through watts — the amplifier continued to be well behaved into the dummy load, easily yielding watts with a little more than watts input. The 12v keying voltage is cut-off to the keying relay until the power on delay has elapsed. To be fancy, I replaced the often-burning-out meter lamps with white LEDs, and cemented a red LED to illuminate the grid meter during the warm up interval.

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About Home. Besides the cooling and mechanical issues, the following needed to be done: New Having been successful with my amplifier I have now decided to take things up a gear and build something even more powerful.

The GS35b is a Russian triode that is relatively cheap and easy to get hold of. Originally designed as power triode for UHF Radar applications it has a plate dissipation of about W.

Many radio amateurs have used this beast as a power triode in HF linear amplifiers in typical grounded grid configuration.

gs35b amplifier schematic

It is similar to the triode in many respects. On our last trip to GB Airspares I picked up this lovely chassis from some sort of aircraft test rig. I have no idea what it was used for but it is about the right size for an amp and had loads of useful bits in it including those fantastic vintage meters. This linear is going to look brilliant and will pack a punch of up to a kilowatt if not more!!

The first job up is to strip down the chassis and get down to the basic framework. The coil on the side is the tank coil for the 80 and m bands.

The total inductance of this coil is 15uH. This used to be available as a kit but I think he got fed up and now just sells the board. This has various safety features built in and will control the biasing.

Next up is to wind the main tank coil. This will cover the 15,20 and 40m bands. The manual that you can download is very easy to follow without any ambiguity. The GS35b is one of the few valves where you have to make up your own base. Next job is to mount all the boards on the RF deck.

The chassis front panel has been modified to cover up the spaces left by two meters that were not required. The wiring has now been completed so before I can switch on I will need to condition the valve. This involves running it for about a day with just the heater on. Anyone considering building one of these amps must appreciate that the GS35 requires a significant amount of cooling air that has to forced up from the bottom and through the heatsink.

Initially I thought that obtaining a blower that could pump 92 cfm of air would not be an issue and that blowers being blowers would not be that expensive. How wrong that proved to be!! I managed to eventually find a blower but had to get a new one and it cost more than the valve!!! After that period I felt confident to connect up the HT and see what happened, luckily no bangs or sparks and so far so good.

This shows the valve in situ on top of the cathode box.

gs35b amplifier schematic

Note the silicone tube used for the chimney. Most people use PTFE but finding a piece of suitable diameter was impossible. Silicone pipe is good as it is temperature resistant to about degrees C and also has good dielectric properties.Your safety is YOUR responsibility. The information provided here is for information purposes only.

No liability is assumed by providing you with this information. This page was started February 11, and the last update was on July 6, Latest update done on July 6, This project uses dangerous high voltages. These voltages will not just shock you, they will kill you.

Use extreme caution while building, working on and testing. Only YOU can prevent accidents. GSB Medium mu triode vacuum tube. Please work safely. If you don't feel safe, step back and avoid the danger. Don't work on this kind of project while you are tired.

Don't work alone. Don't work with the power on! Remember, capacitors store energy and they can deliver a dangerous shock long after the primary power source has been removed. Keep one hand in your pocket. Mail Archive. Parts Lists. Tube Data.

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Tony's first rule for tubes: Tubes are like women If you feel that you must have two, keep them in separate houses, and don't let them know about each other. If one isn't good enough for you, get a better one. In other words, if one tube isn't enough for you, don't run two, get a bigger tube! The next logical step above a single GSB isn't two of them It virtually eliminates the stray inductance in the grid circuit. Click on the picture to see the details of the construction.

Tube Tester and Filament Burn In Jig - Here's my answer to cooking the tubes for days and then testing them before inserting them in an amp. Note - I have learned an important lesson with this jig. The filament alone heats the entire bottom of this tube and even with the fan blowing air into the box, the bottom of the tube will get too hot to hold in your hand. This is an important lesson regarding cooling of the tube, particularly the grid ring and filament seals. Do NOT run this tube without air, lots of air, blowing around its base and through the anode cooler.

There is 38 watts of heat from the filament alone. Do yours glow? My bet is that they do. What color are they? Want to share your pictures?Power Supply Schematic. Each pole of the relay carries a VAC leg of the mains. A solid-state TDR would also work if you have one. In the interim, as soon as the DPST high current relay trips, R2 an Ohmite 25w 50ohm wire-wound shorts the 28V relay contacts and provides a limited mains load to the filter capacitors for the length of the delay. The transformer feeds the full-wave bridge diode configuration on a large PC board mounted above the capacitor bank.

The ETO supply is from the early 80s and uses one large diode for each leg of the bridge.

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I have been unable to find a spec sheet or otherwise cross-reference the part number, but given the overall engineering of the supply I am certain they far exceed the necessary specs of the PS as proved already during a tube flashover in the opening stages of working out the "kinks"- it took out meter protection diodes and a Z inductor I had in the tank circuit at the time but never bothered the bridge diodes at all.

Legged strings of 1N diodes or large bridge diode "blocks" could just as easily work, just be sure the components used on each leg of the bridge match the other legs. The whole assembly is mounted on its own PC board and the capacitors are staggered to allow ample airflow.

On the positive side of the diode bridge a string of four 1 MEG precision resistors supply a reference voltage for a Hoyt kv voltmeter. The B- side of the board is fed thru a amp Hoyt ammeter in series. A ohm 10 watt ceramic resisitor, 1N diode and a 3kv.

This float scheme is identical to that used in the Lunar-Link LA amp series. Glitch resistance is provided by 2 paralleled 25 ohm 50 watt vitreous enamel power resistors mounted directly in front of the HV supply fan. This is overkill, but I had them so I used them. In some cases a VAC neutral wire has been routed back to the power supply deck- this is probably overkill as there is a large chassis to chassis common ground, but redundancy can't hurt.

Remember, when selecting connector plugs, be sure to consider the "idiot" factor- never use plugs which, in the event of an "unconnected" powerup, allow direct contact to an unshielded live voltage source. This means, in my case, a female connector in the HV Supply chassis and a male connector in the RF deck chassis. In this fashion it is more difficult to contact the control voltages in the event the PS is turned on with an unpluged molex.

Finally, both the DC voltmeter and the ammeter have a pair of 1N diodes and a 1kv.

gs35b amplifier schematic

RF Deck Schematic.Schematic Diagram. The jumper J on the board should be cut only if you need to increase the bias voltage over 39 Volts. Be sure you do not cut the jumper unless you need the increased bias Voltage. Typical bias circuits using a power Zener diode to bias the cathode of a triode. Typical connection diagram for the bias board. Mount the bias board as shown here. The screw, nut and lock washer may be reversed.

The thermo pad and shoulder washer must remain as shown. This bias board is an easy two wire replacement for the zener diode used in many Grounded Grid amplifiers as well as the ideal bias board to use for Grounded Grid amplifier retrofits. The circuit is a very common one using the TL precision variable voltage reference with a TIP PNP power darlington transistor as the active element that is used to regulate the bias voltage.

You have the option of adjusting your bias over the range of approximately 3. The advantage of adjustable bias is being able to adjust the idling current on your tube s. The 10K potentiometer, R1, provides a bias adjustment range of approximately 3.

For initial installation the potentiometer should be set for maximum bias to insure you start your adjustment at the lowest plate current. Fuse the circuit just above the maximum expected plate current.

GS35b-2 Twin GS35b Mule With Specials

The TIP tab mount transistor, Q1, MUST be securely mounted to a heat sink or aluminum chassis with the thermo pad, shoulder washer and screw provided. Parts layout The jumper J on the board should be cut only if you need to increase the bias voltage over 39 Volts.I was finish in December I like to show you here the steps from this project. I got the tube from cheap eBay. Nobody liked to buy this tube because the cooler was a little bit deformed. I repaired the cooler and clean the tube.

I collect the parts for this linear over one year on flee-markets. The case will be a 19 inch 6 inch high server case. I will modify it. I take all the stuff out and i made some new sheets for the holes. The front is a 2 mm thick aluminium sheet. I made a double bottom sheet, so the cables can be under the bottom.

I start with the tube socket. A fried of me, DF2PY, made me this socket. I coat it with silver. That was the first time I tried the tube in the socket. The finish socket with the input circuit from under side. From upper side it looks like this.

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The air can flow trough the socket. Over the tube comes a chimney. Under the socket is the air flow sheet. All the air must trough the tube socket.

This are the power supple circuit boards. I made all by my self. This is the self made adapter for the big load capacitor.

gs35b amplifier schematic

Here he is build in, with the adapter. The UHF trap for the tube. The first version of the anode coil, everything is self made. This is POM plastic. The plate side of the PI-Filter. A overview of the work, so far. Now is everything finish inside.

The underside is finish too.Power Supply. Conecting Cable. Tuned Input. J Box. Oil System. The advantage of a pdf file is that you can zoom as much as you want and it does not get fuzzy. This fan was also taken from a junk computer. F3 line 3 is a box fan 18 inches square or so with a automotive transmission oil cooler attached.

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P1 line2 is a little giant model pump to circulate the transformer cooling oil. Power On: Power switches S1 and S2 line 3S2 is normally the power switch as S1 is normally left in the on position as K1 main contactor line 4 is energized via S2.

The K2 relay is not energized until the TDR timing relay in the control circuit chassis provides a second delay for filament heating. As this is a capacitor input DC supply it appears as a dead short to T1 initially and the voltage across the K3 coil line 5 remains very low due to the voltage drop across R12, as the filter capacitors charge up the voltage across the K3 coil rises and after about a second K3 energizes shorting out R Also power supplies 1 and 2, inside control chassis have been energized, and fans F1 line 6F2 line 8F3 line 3and Pump P1 line2 have been energized.

My newest selfmade linear with one GS35B

Switching Supply 1, 12 VDC filament supply, has in-rush current protection built in. The GS35B is rated at This arrangement allows the filament to attain full voltage before the TDR begins its filament heating time delay. The filament supply is adjusted to supply When the TDR relay times out NO contacts 8 and 6 of TDR line 11 close energizing RL1 relay, and the other set of NO contacts close allowing the K2 relay to energize, this arrangement allows the tube to reach full heating of the filament before applying the high voltage.

They do not have pin numbers, on the ladder diagram everything is shown in standby, power off conditions.

GS35b HF Linear Amplifier

When RL1 energizes its NO contacts close, RL2 will be energized providing there is not a grid overload present and that the flow switch is closed. Line 12 of ladder diagram. A note about relay RL4, this relay is normally energized via the NC contacts 9 and 3 line 18 of the OL relay opening the NC contacts of RL4 in line 19 of the ladder diagram and thereby not lighting the red overload light until the OL relay energizes and de-energizing the RL4 relay causing the RL4 NC contacts to close.

The bias is provided by the W4ZT bias board, the adjustment is made via R2 a 10K ohm wire wound pot from the front panel, it is adjusted to obtain ma idling grid current. This amplifier works extremely well, I get between to watts out on all bands driving it with my TSS.

It makes almost no noise, the two small cooling fans are whisper fans and if you don't listen very close with no receiver noise you really do not even hear them. In the summer you can operate for long durations like in a contest, the amp just idles along and your area does not heat up from extra heat.


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