DP-AMP Sixty One Amplifier

DP-AMP Sixty One Amplifier

Now it's getting COLD!

After the HVF-1k2 power amplifier had been successfully reproduced so many times worldwide, it was time to take a fresh look at the concept. There were no faults that could have been eliminated because the HFV-1k2 had long been technically mature.

Nevertheless, my fingers were itching to do something again and so I looked at what could be improved, after all, the HVF-1k2 had been running smoothly for so many years.

Once the ideas started flowing!
A housing made of anodized aluminium and laser marking, it should be beautiful and stable, affordable and of course it should be stylish. One point that always posed a challenge for the OM's in all the replicas was the mechanics.
Now there is a completely prefabricated housing with all cut-outs, holes and threads.

The air cooling worked well and the Fischer cooling fin with two fans had proved its worth.
However, a water cooling system like this would be great, but not as clumsy as in many other power amplifiers!
No, something new had to be found here, something that didn't even exist yet.

I developed a copper plate with screwed connections for the hoses. This meant that safe and proven fittings could be used. The water channels were not simply clumsily milled recesses or soldered-on tubes.
The heat is generated under the LDMOS and has to be dissipated.
So the solution is to flush this area under the LDMOS even better and insert additional “fins” under the LDMOS to increase the contact surface between the water and the copper.

This in turn required many simulations in order to achieve the best possible result. The flow rate, turbulence at the fins, water pressure and temperatures were simulated.
Of course, this is time-consuming, you learn a lot and it was great fun, especially when the result is completely convincing.

The modules have also been revised.
The PA module was given a new input transformer, which is easier to manufacture and also covers the range from 1.8 MHz (160m) to 70 MHz (4m) without any problems. A change to the output transformer was also necessary to go beyond 50 MHz (6m).

The LPF module has been completely redeveloped.
A 7th order Chebyshev filter for 14 bands, including possible new bands such as the 8m band. The RX/TX switching is done as always on the LPF board.

A new module for switching 3 antennas incl. bypass function for the ATU.

Changes to the controller module, conversion to PWM, additional connection for the water pump and connection for the new display.

Measuring is also an important point
In order to be able to measure correctly and reliably and, above all, linearly from 1.8 MHz to 70 MHz, a separate directional coupler module was added with two AD 8307 from Analog Devices.

The new supply module switches the 230V voltages to the consumers, the 50V are switched and also measured with a HAL sensor. This has made the wiring much simpler.

New display and elimination of the Raspberry PI!
Yes, the Raspberry Pi and the HDMI display used to be modern and this combination worked without any problems.
The disadvantage was booting the Amplifier, maintaining and updating the Raspberry PI.
Now it is much faster with new high-performance HMI (Human Mashine Interface) displays. No maintenance on the operating system, no waiting time, just switch on and get started!

The software has been completely rewritten, the GUI is now even clearer and also fills the hearts of technicians with joy. The ATU has become even faster, errors are logged, an antenna matrix is available and much more!

The ATU module was only slightly revised, mainly the wired capacitors were replaced by SMD.

All in all, it was a lot of effort, but once again it was worth it.

Of course, many hobbyists will get “suggestions” and it will be copied again.
That used to annoy me, especially with the German “professionals” who came to me for information and then made a name for themselves as experts, published my knowledge in magazines or lined their pockets with companies.
Now I don't care, because I don't need to make a name for myself, that should be done by others who seem to need it and have nothing else in life.