I4FAF Amateur Radio HF "really" linear,
rugged and trusted, Tetrode Tube Linear Amplifier experience.
Our HF TX system philosofy has been, since many years, to
have available an amplifier which needs a drive level (ONLY when necessary)
around 50 to 65 watts MAXIMUM as RF input level (to get the
maximum power available, and legally permitted, from a linear amplifier
accessory), or LOWER, for
even better IMD, lower harmonics levels, and for longer equipment
life and enjoiable use of the system with lower heat from the transceiver-exiter
finals. To achieve our goals we used a tetrode tube with 50 ohm
grid input drive which has also lower High Voltage Anode requirements,
(we used a conservative anode voltage value of about V=2100-2200 under load,
or about V=2500-2600 no load obtained with a power supply
transformer with a secondary ac value of 1850 V x 1,41 with full wave
rectification) strictly well inside the maximum Voltages specifications of the tube
manufacturer for longer tube life, with stabilised-regulated voltages and
overdrive protections. I4FAF started to investigate, along with his friend
Paolo
I4PZP (owner of
HAM
CENTER SRL in Borgo Nuovo di Pontecchio Marconi (BO), professional Philips glass tetrode tube for Amateur Radio in 1974
(after a comparative evaluation of the well famous triode 3-500Z or better
3-500ZG, graphite). Now we use a ceramic-metal rugged tetrode tube. Of course
do not use more RF output power than reasonably needed to achieve a qso!.
Try first low power: often it is more enjoiable to get a qso with a
lower power level than the maximum you have available. The transceiver needs to
be equipped with a good RF output level control, not only in CW or during
tune, but also in SSB to keep always under control the drive level.
Remember to use a good PEP RF Wattmeter to monitor the power output level when
operating in phone SSB mode. A good low pass filter accessory that
attenuates harmonic further above 30 Mhz can be of help. Our
experience proves that we have been able to work all the DX, Expeditions and
Contests as well with the one 4cx800A version, but as in a nice FERRARI car,
if you have a fine drive control you can run lower power also with a strong and
trusted linear ampl. still with benefits and longer equipment life.
Remember that experience in HF amateur radio
operations and improvements in the antenna system can often make the real
difference.
SRC 800 (1998) HF Amateur Radio Linear Amplifier with one 4CX800A |
SRC 2001 (2001) HF Amateur Radio Linear Amplifier with one 4CX800A |
SRC 2000 (2000) HF Amateur Radio Linear Amplifier with two 4CX800A |
OUR LINEAR
AMPLIFIERS WITH TETRODE TUBES PICTURE GALLERY (17 SMALL PICTURES TO
CLICK ON TO ENLARGE) (Homebrew unique model for personal knowledge and amateur radio use only) |
Now let's see the new BLA600 RM - ITALY 500W out 160 to 6m with pin diode fast antenna relay, with LDMOSFET by Freescale (NXP)
official video on youtube by RM Italy here
Now let's see some new Linear Amplifiers with Mosfet
devices at around 48V
BLA1000 by RM Italy
BLA
1000 - RM Italy - early Review by IK4AUY
(.pdf in italiano)
BLA1000 two tones RF
IMD test with a newly low IMD RF coupler design by I4SBX at 410 pep out (with 24Wpep RF in, DFreq=1200Hz) |
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BLA1000 two tones RF
IMD test with a newly low IMD RF coupler design by I4SBX at 550W pep out (with 2x15W CW RF tones coupled or 31Wpep RF in, DFreq=1200Hz) |
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BLA1000 two tones RF
IMD test with a newly low IMD RF coupler design by I4SBX at 700 pep out (with 50Wpep RF in, DFreq=1200Hz) at 14.2MHz |
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BLA1000 two tones RF
IMD test with a newly low IMD RF coupler design by I4SBX |
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above BLA1OOO . same test it looks good: 3° order IMD close to 40dB down at 500W pep out and it improves further out after 5th order |
(48V Mosfets 2x SD2941-10, 10Watts Pin - 300Watts Pout)
ST Microelectronics says about SD2941-10 mosfets: The SD2941-10 is a gold metalized N-channel MOS field-effect RF power transistor, intended for use in 50 V dc large signal applications up to 230 MHz. It offers 25% lower RDS(ON) than the industry standard, with 20% higher PSAT than ST's SD2931-10 device. The SD2941-10 is housed in the low thermal non-pedestal package, offering 25% lower thermal resistance than the industry standard, thus rendering it the "best-in-class" transistor for ISM applications, where reliability and ruggedness are critical factors.
BLA 350 by RM Italy (a very early
unit)
Pin -Pout test in some bands:
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Power In | Power Out | wattmeter N8LP | ||||||||||||||
Band | W-CW tune | W on 50Ohm dummy Load | LP-100A | ||||||||||||||
160M. |
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40M |
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20M |
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15M |
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10M |
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BLA 350 (SN. 130911 - Jan. 2012 - test by
IK4AUY) |
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Think about using any transceivers like KX3 Elecraft or TEN-TEC mod 539 Argonaut VI or any other HF transceivers in which you can adjust output power at max 10-12Watt to drive this linear amplifier and you will get out around 250-300 Watts, or less if you set the driving power lower than maximum, at a very favourable price for each Watt ratio.
,
BLA 350
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HLA 305 V 13.8V 250W HF Linear amplifier
RM -ITALY review on HAMRADIOWEB Forum
KPA500 Elecraft - early review by IK4AUY
(.pdf in italiano)
Some links about Amateur Radio Manufacturer of Linear Amplifiers with Tetrode Tubes |
ACOM | ALPIN100 and 200 by Reimesch Kommunikationssysteme GMBH | Alpha Amplifiers |
Emtron
(Australia) DX1b (one 4cx800A) |
Leitner Elettronica (It.) 4CX800A amateur radio linear ampls | OM Power |
QRO tech (lin ampl with 4CX800A) | Ameritron |
More links: | |
G3SEK Technical site about control boards for tetrode tubes | WA6BOB a lot of links |
ND2X/5 QRO info, links about low cost tube linear ampl. | |
4CX800A Svetlana Data Sheet | |
HAM CENTER SRL (Borgonuovo di Pontecchio Marconi - Bo) air variable capacitors suited for linear amplifiers |
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Some links about Amateur Radio Manufacturer of solid state Mosfets Linear Amplifiers |
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BLA1000 RM Italy (1000W - 50V 2 x MRF 157 Mosfets full automatic HF/6M) BLA600 - 500W with LDMosfet ad pin diode fast ant. relay
BLA350 (300W - 2x SD2941-10 48V
rugged Mosfets) |
ELECRAFT KPA500 (500W mosfet HF/6m) |
SPE EXPERT 1K-FA - 1.3K- 1.5K - 2K-FA | |
YAESU Quadra System |
RF-POWER |
A beautiful "ensemble" view about
HAM CENTER SRL (Bologna - ITALY) variable capacitors specifically designed for HF RF Power amplifiers with TUBES My father I4FAF helped I4PZP to develop these rugged mechanical units. |
your right: close detail of specifically designed split section to better tune 10 meters |
your left: one more detailed view of split section variable capacitors
to improve 10 meters (28 Mhz) amateur band tune (with lower residual capacity). |
Updated April 14 - 2018