600 watt hf amplifier

600 watt hf amplifier DEFAULT

This project is meant to demonstrate the capabilities of the MRF300 transistors as linear broadband devices in the 2-50MHz range and to be used by radio amateurs as a starting point for a medium-high power amplifier. This is also my entry to the NXP Homebrew RF Design Challenge 2019.

A600 Broadband 600W linear amplifier with MRF300 transistors

To achieve the target of 600W output while also minimizing the level of even-number harmonics, a “push-pull” configuration of two transistors is used. Luckily, the manufacturer made it easy to design the PCB layout for such a thing by offering two versions (the MRF300AN & MRF300BN) that have mirrored pinout. The common TO-247 package is used, with the source connected to the tab.

Each individual MRF300 LDMOS transistor is specified at 330W output over a 1.8-250MHz working frequency range, a maximum 28dB of gain and over 70% efficiency. The recommended supply range is 30-50Vdc. By studying the specifications, it looks like with correct broadband matching and some operational safety margin we can get close to 600W output at a voltage of around 45V across a resonably large bandwidth; the aim is to cover 1.8 to 54MHz.

Main challenges when designing this amplifier are related to achieving good input and output matching over the entire frequency range as well as maintaining high and flat gain. Good linearity and a low level of harmonic products are mandatory. As the TO-247 is not a package specifically designed for high-power RF, there are some challenges with thermal design and PCB layout as well.

Circuit Description

The circuit schematic can be seen below. For input a 4:1 transformer is used, along with a 33ohm resistor (R1) that partially dampens the reactive response and improves input matching.

A600 Broadband 600W linear amplifier with MRF300 transistors

The idle currentfor the MRF300 LDMOS transistors is set at 300mA each, with a bias gate voltage of around 2.7V. To achieve this value, a LM317HV high voltage linear regulator takes the supply voltage and adjusts it down to a value around 8-10V, which is further divided down to the exact value via individual adjustable multi-turn potentiometers.

A negative-coefficient thermistor is present in the regulator’s feedback loop so when the heatsink temperature increases the MRF300 gate bias voltage decreases slightly in order to maintain the same idle current. An external signal can cut off this voltage in order to reduce power consumption when the amplifier is not used.

The 560 ohm resistors (R2 and R3) provide negative feedback, making the amplifier more predictible in response and improving IMD performance. For a small increase in overall gain, it is worth investigating increasing their value.

Matching the output to 50ohm is where the real challenge is. For maximum efficiency across a large bandwidth, transmission line transformers (TLT) are the best option and the closest transformation ratios possible are 1:4 or 1:9. With 50V supply and a 1:4 transformer, the maximum output power that can be obtained is around 400W as the theoretical load impedance for each transistor is too high. With a 1:9 transformer higher power can be achieved but the matching becomes more critical; the supply voltage can be reduced below 50V in order to improve efficiency, but current needs to be actively monitored and kept in the safe area (below 20A in total).

For minimal losses, the coaxial cable used in the TLT has to have a characteristic impedance that is the geometric mean of the input and output impedances. As this is a 1:9 transformer and the output has to be 50ohm, the input impendance works out as 50/9 = 5.56ohm and the coax characteristic impedance is sqrt(50*5.56) = 16.67ohm. I chose TC-18 coaxial cable specifically designed for this purpose, that has 17ohm impedance and uses high quality materials so it can handle high power and temperature. 3 lengths of RG-316 in paralel can be used as well in order to achieve the 17ohm impedance, but RG-316 is harder to work with and it might be a challenge to fit it 9 times within usual ferrite cores.

The length of coaxial is best kept short in order to maintain efficiency at high frequencies, ideally below 1/10 of a wavelength at the maximum frequency. 30cm is enough for 3 turns through the popular 26xx540002 bead ferrite cores from Fair-Rite and taking the ~0.7 velocity factor into account, it stays below that.

Choosing the ferrite core for the output transformer is key to achieve the best performance. The first prototype used Fair-Rite 2667540002 ferrite beads (material 67) in an attempt to achieve the widest working range possible with best efficiency; this sacrifices performance in the lower amateur radio bands, as below 10MHz there is a significant drop in efficiency. Laird 28B1020-100 cores have been tested as well, with relatively similar performance to the material 67 Fair-Rite cores.

View full project

NXP Homebrew RF Design Challenge 2019

Categories NEWSSours: https://radioaficion.com/news/600w-hf-amplifier/

A low cost 600 watt ultra-linear amplifier

A low cost 600 watt ultra-linear amplifier for 40, 20, 17, 15, 12, and 10m

This compact little amplifier is the brain-child of Pat Murdoch, ZL1AXB, in Auckland, New Zealand. It is only 11″ wide, 4″ high, and 9″ deep. In most respects it is a typical grounded grid linear amplifier, with the exception of a rather unique tuned cathode input circuit that was developed by Pat over 10 years ago.

To best describe this unique circuit; the 813’s directly heated cathode (filament) becomes an integral part of the resonant cathode tuning circuit by the use of a coaxial coil (L2). The coil is made of 3/16″ copper tubing which is connected directly to one of the tube’s filament terminals, and an insulated #12 wire passing through the interior of the coil’s tubing is connected to the other. The filament voltage is then applied to the “cold” end of the coil, as well as its interior wire, as shown in the schematic drawing below.

The coaxial input coil is resonated in parallel by a 1000 pf variable capacitor (C3), which is mounted above ground and tuned with an insulated shaft. The LC circuit is shunted by a 2.5K ohm resistor to reduce its Q, and tunes from 7 mHz to 30 mHz, thus eliminating the need for an input band-switch. For this reason it is necessary that C3 have off-center rotor plates for ease of tuning the higher frequencies. With the input tap position on L2 set properly, a near-perfect 50 ohm input impedance will be realized on all bands.

Aside from its broad-band input tuning advantage, Pat’s unique input circuit stands apart in two other significant ways: it eliminates virtually all input mismatch distortion, and it increases the efficiency and stability of the 813 dramatically.

The maximum output power of a single 813 would normally be around 300w PEP below 21 mHz. With approximately 50w input, this amplifier produces 600w PEP output nominally, and around 500w PEP output at 29 mHz. Its intermodulation and harmonic distortion products are well below 40 dB down from its maximum power output, and its tendency toward parasitic oscillations is so low that a parasitic plate choke is unnecessary.

To operate the 813 at these output power levels, a sufficient volume of air moving over the tube’s glass envelope is required to dissipate the increased heat. In this case, the tube is mounted horizontally, about ½” above the case bottom and about 1″ from the rear of the case, directly in front of a 3″ exhaust fan that is mounted on the rear panel which draws cooling air around the envelope, from the air holes in the top and bottom of the case (see photo of case below). The air holes in the bottom of the case are located below the rear of the plate coil (L1). A low value 10w resistor can be placed in series with the Fan’s AC supply to slightly reduce the fan speed, thus reduce noise.

A 3kv @ 350ma continuous duty rated power supply is required for the 813 to achieve its maximum output power. A schematic for a suitable HV power supply is shown at the bottom of this page.

L1 consists of two 2″ ID coils in series that are: 8 turns of 3/16″ copper tubing with the windings spaced about 3/32″, followed by 8 turns of #8 copper wire with the windings spaced similarly. Counting from the C1 end, the following taps are placed at: 2 turn for 10m, 2½ turns for 12m, 4 turns for 15m, 5 turns for 17m, 7½ turns for 20m, and the full coil for 40m. If one wants 30m, the tap is at 11 turns.

Since Pat winds his own transformers, the 12v relay winding is integrated in T1 thus a similar transformer may be unavailable. A small 12v transformer suitable for supplying the relay voltage (T2) may be placed below C3’s tuning shaft extension, near the front panel.

The following schematics should provide enough details to construct a similar amplifier. 813 tubes can be found via the internet from around $5.00 used, to up to $30.00 new. 813’s that have gone soft can usually be rejuvenated by applying 10½ volts to the filaments for an hour or two.

It is important to note, this supply is not adequate for the 1kw version of the amplifier. For this, the current rating of T-3 must be increased to 1.5 amps.

Article originally available at http://www.raibeam.co m/ zl1axb / 813_amp.html

Sours: http://www.iw5edi.com/technical-articles/a-low-cost-600-watt-ultra-linear-amplifier
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Ameritron ALS-600SX
600 Watt Solid State Amplifier with Switching Power Supply, 220 VAC

No tuning, no fuss, no worries - just turn on and operate ... includes AC power supply, 600 Watts output, continuous 1.5-22 MHz coverage, instant bandswitching, no warm up, no tubes to baby, fully SWR protected, extremely quiet, very compact

-Ameritrons revolutionary ALS-600 is amateur radios ONLY linear amplifier that uses four rugged TMOS RF power FETs - gives unequaled no tune solid state performance.

-Includes Ameritrons no tune FET Amplifier and a 120/220 VAC, 50/60 Hz AC power supply for home operation.

-Instant bandswitching, no tuning, no warm up

-Output Power - 600 Watts PEP, 500 Watts CW

-SWR Protection - prevents amplifier damage if you switch to wrong band, use wrong antenna or have high SWR

-Over Power Protection - if output forward power or reflected power exceeds safe level, output power is automatically reduced to prevent amplifier damage by controlling ALC to exciter.

-Extremely quiet - low speed, low volume fan is so quiet youll hardly know its there, unlike noisy blowers used in other amps.

-Very Compact - 6 x 9 1/2 x 12 inch amplifier takes up less desktop space than your transceiver and weighs 12 1/2 pounds.

-Illuminated Cross-Needle SWR/Wattmeter - lets you read SWR, forward and reflected peak power simultaneously

-Operate/Standby Switch - lets you run "barefoot", but you can instantly switch to full power if you need it.

-Front Panel ALC Control - exclusive Ameritron feature - convenient front panel control lets you adjust your output power.

-Transmit, ALC SWR LED indicators - keeps you informed.

-12 VDC output jack - lets you power low current accessories.

-Separate ALS-600PS power supply (included) can be placed conveniently out of the way and plugged into your nearest 120 VAC outlet - no special wiring needed. Made in USA.

-enjoy 600 Watts of no tune solid state power. Call your favorite dealer for your best price, order ALS-600 with power supply.

-Massive choke input filter greatly improves voltage regulations nd reduces peak AC line current.

-Ameritrons exclusive Multi-Voltage Power Transformer lets you compensate for stressful high line voltage and performance robbing low line voltage.

-Step Start Inrush Protection stops damaging inrush currents and extends life of power supply components.

-Illuminated Cross-Needle Meter monitors voltage and current of 50 VDC line.

-Extremely quiet fan.

-Very Compact 6" x 9 ½" x 12" - can be placed conveniently out-of-way.

-Wired for 120 VAC, supplies 50 VDC at 25 amps to ALS-600 amplifier.

-Also use on 100-130 VAC and 220-250 VAC, 50/60 Hz.

-Draws less than 12 amps at 100 VAC and less than 6 amps at 230 VAC.

Made in the USA

user manual button





Sours: https://www.gpscentral.ca/products/ameritron/als-600sx.html

Hf amplifier watt 600

Reviews For: GBHS HAL 600 solid state linear amplifier

IK2QBARating: 2020-11-11
Fantastic !!Time Owned: more than 12 months.
I am really very happy with this amplifier, it is small, light, it works very well, it has all the protections that have saved me several times, it comes out so much power on all bands and the modulation is always beautiful, it is completely automatic. Bravo Giordano I would buy it back another 1,000 times great product!


Sono davvero molto contento di questo amplificatore, è piccolo, leggero, funziona molto bene, ha tutte le protezioni che mi hanno salvato varie volte, esce tanta potenza su tutte le bande e la modulazione è bellissima sempre, è completamente automatico. Bravo Giordano lo ricomprerei altre 1.000 volte grande prodotto !

HZ1FIRating: 2018-02-19
GBHS weak supportTime Owned: more than 12 months.
Review of the HF amplifier HAL1200 Atlantic from GBHS Italy

Features of the PA:
All Amateur Bands, 160m – 6m, Automatic Band Change, Output Power : 1000W CW of HF, 500 W CW on 6 meters, 4 x SD2933 as final Transistors

I am really disappointed about this kind of PA and the manufacturer.

Weak temperature concept:
The temperature concept is weak. If you start transmitting, the temperature of the PA will increasing fast and fans are starting to run. After about 30 seconds transmitting with full power, all fans are on with maximum speed. Because of the noise, you need a headphone. It is very loud. I cannot recommend this PA for contests or DX expeditions. If you have only 1 contest QSO per minute and do not call CQ, the PA will be OK, but if you transmit 50% or more of your time (like CQ or more QSO per minute), the PA will be very hot and will switch off automatically.

Noise from the power supply or display:
If you switch the PA on, you will hear a noise (QRN) on the higher bands. I was not measuring it, but definitely you will hear it, maybe 1 or 2 S-steps noise is coming from the PA. When you work weak stations is not nice when this noise comes into the DX-Stations.

Weak automatic Band switching:
In CW and RTTY the automatic band switching is working well. In SSB sometimes the PA is switching to another band if you transmit. If this happens, the PA will switch of immediately, because of bad SWR. The unexpected band switching happens often, so I decided to switch the bands manually, automatic band switching in SSB is impossible. When I connected the PA to my TRX, I got a CAT Error, but I do not exactly is it my station or the PA itself and I was not trying to find where the problem is.

Difficult to reduce output power to low levels:
You can switch to maximum power (1200 watts) or to the half of power (600 watts). If you would have less, for this PA it works not well. With less input power, the output will be 0 watts till a certain level of input power. At this point the PA will start to send with a power close to the maximum power. So, if you try to send with 250W or 700W, this will not be possible.

Protection Circuits:
The documentation of the PA shows, there are a lot of protection circuits included (bad SWR, Overload, Temperature etc.) In real it is not properly working. I was not working hard with the PA, but the final transistors damaged after a half year of use because of temperature.

Very bad service from the manufacturer (GBHS):
After my final transistors damaged (within the guarantee time) I sent my PA in August 2017 to the manufacturer. He wants to repair the PA only when I pay the repair. After 5 months of sharing a lot of e-mails the manufacturer had every time another excuse, why this case will not be his fault. To my questions about the protection circuits, never he was answering. After 5 months (December 2017) he asked me again to pay the repair, because of a mechanical damage, like transportation harm, what is not part of the guarantee. Before, in all the other e-mails never he mentioned harm like this.

I cannot recommend this PA and this manufacturer. In my active time I made more than 250000 QSO. In 2017 I made about 30000 QSO (5Z4/DL2RMC, HZ1FI, ZA/DL2RMC and QSOs from home). My plan was to use this PA for my expeditions, what never was possible. Maybe I did 20 or 30 QSO with the HAL1200.

Best 73
DK6MPRating: 2016-07-03
Good for Jumping between the Bands , Poor for Waeak Signals !Time Owned: more than 12 months.
i had this Very Quick , Small and Easy to Use Amplifier .

I Love it to Jump from Station to Station , from Band to Band.

But the PowerSuplay or the Display makes Noise on 10-20m Band
( i have Videos were you can see the Wandering Noise on Waterfall )
When you work VERY Weak Stations is not real Cool when this noise comes into the DX-Stations when you think they call you in Pile UP

Also i get a CAT Error with the TS590SG .
( my Mail with the Cat Error i write in the Time of Warranty to the Manufacturer GBHS )
I Wait more than a Half Year for an Update
( then the PA was not longer in Warranty )

The Manufacturer will only fix that Cat issue only when i pay Porto around 40-50€ € to the Manufacturer and 44€ back , also Around 80-95€

Thant's not good Support for a PA with 600 Watts for 1800€

i run the PA in Automode but in this mode you can`t fine adjust the Output Power !!!

i Sell it an buy y Better Product !
What not generate Noise on the Bands !!!
Sours: https://www.eham.net/reviews/view-product?id=11688


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Seller:dxworld.e2✉️(62)96.9%, Location:thessaloniki, Ships to: Worldwide, Item:233127345056HF LINEAR AMPLIFIER 600W 1.5-30MHz SD2943. DX WORLD ELECTRONICS HF LINEAR AMPLIFIER BOARD 600W RF INPUT: 15WRF OUTPUT: 600WFREQ:1.5-30MHz BROADBANDPOWER SUPPLY: 48-55V/25AAUTO BIAS SUPPLY:12-13.8VIN/OUT IMPEND. 50 OHMMOSFETS:2x SD2943 PUSH PULLIdq 700mA each mosfet ,total 1.4ABOARD SIZE: 100x150mm PACKAGE INCLUDE SCHEMATIC AND INFORMATION GUIDE. AUTO BIAS MEANS THAT WHEN TRANSMIT (TX) THE BIAS AUTOMATIC GOES ON AND WHEN IN RECEIVE MODE (RX) GOES OFF SO THE MOSFETS ARE OFF AND THERE IS NO CURRENT FLOW THIS WAY THE AMPLIFIER RUNS COOLER. A temperature regulated bias circuit and a high power low loss wide band transmissionline type transformers are used in this device. HEATSINK NOT INCLUDED YOU CAN WATCH VIDEO TEST ON YOU TUBETITTLE: HF LINEAR AMPLIFIER 600W SD2943CHANNEL: DX WORLD ELECTRONICS ANY MORE INFORMATION PLEASE CONTACT ME73sCondition:Open box, Condition:Handmade, All returns accepted:ReturnsNotAccepted, Supported Modes:AM, Band:HF, Amplifier Class:AB

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  Amplifier Description

  • There's an old axiom in amateur radio which states "Life's too short for QRP." While I generally disagree, it certainly appears to be true for 75m AM operation here in central North America, where a one watt carrier can quickly become buried in QRN & QRM. This amplifier is a mate for the QRP 75m AM Transceiver described elsewhere at this site.
  • The amplifier uses four Motorola MRF150 50 volt TMOS power FETs configured in push - pull/parallel and biased for class AB linear operation. This scheme yields a power gain of 20db. The 1 watt drive from the "Wheat Box" will produce a 100 watt carrier (400 watts PEP @100% modulation) with headroom to spare.
  • There's little original design here. The basic 2  30MHz PA brick is straight from Motorola's application note EB104. The power supply, low-pass output filter, control circuitry and instrumentation are mine. Still, I would describe this project as mostly an exercise in packaging.

  Some Amplifier Highlights

eb104  The EB104 Circuit Board


  Data Sheets

  •   View or download the Motorola EB104 Engineering Bulletin (191K)  
  •   View or download the MRF150 Data Sheet (189K)
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Sours: https://www.qsl.net/k9gdt/radio/600w/600w.htm

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