Frequently Asked Questions

Many customers asked us:

- Why is my new ACOM solid-state amplifier noisier than my old ACOM tube-based amplifier?
- Is there something wrong with my new amp?

First, we want to note that ACOM is highly focused on minimizing the noise level of our products, as this is an important characteristic for our customers.
Therefore, ACOM uses fans from the Japanese company NMB as the most suitable for our products. This choice is the result of long and extensive in-house testing of many fan models from different manufacturers.

Answer | The short answer is: NO, everything is absolutely normal with your new amplifier.
We understand that this answer requires more in-depth information, and therefore, here is the technical explanation of this situation.

Technical explanation | We must be very clear that the comparison of noise levels of 2 amplifiers - solid-state and tube-based, with approximately the same output power - and the ham's expectation for equal noise levels is not technically correct due to the totally different electronic and mechanical design of these devices.
The solid-state amplifiers require much more airflow for cooling than tube amplifiers (and more airflow always results in more noise). There are 2 main reasons for that:

• Metal-ceramic radio lamps withstand even up to more than 200 degrees Celsius (392 degrees F), and transistor ones withstand many times less;
• Different mechanical designs of cooling (airflow path for effective cooling).

Lets, for example, see the ACOM 1000 tube-based and ACOM 1200 solid-state amplifiers, which have a similar dissipated thermal power. Even though ACOM uses in its products the most silent model fans and extremely effective heatsinks, the generated noise by ACOM 1200S is higher than the noise from ACOM 1000. And this is normal, as we explained.

As we often have questions about Standing Wave Radio in connection with the usage of our amplifiers and tuners we recommend reading the article written by Darrin Walraven (K5DVW) and published in ARRL QST in November 2006 (the article is available at www.arrl.org also).

Download article | PDF file

ACOM products are mainly designed for the amateur (HAM radio) market.

Due to FCC regulations in the USA, EU regulations, and similar government regulations worldwide, ACOM can not legally modify the transmitting frequency range of its HF amplifiers. By reason of that, ACOM does not disclose or distribute information on how to modify the frequency range of its amplifiers.

The MARS (Military Auxiliary Radio System in the USA) used frequencies outside legal amateur bands. Generally, all HAM users must adhere to the applicable regional band plans and laws regarding specific allocations and limitations. I.e., making any kind of modifications to our amplifiers that you own is solely at your own risk and your responsibility.

For detailed information and possible solutions, please contact your local dealer.
The USA customers can contact our local Service & Repair Partners.

In specific business cases, extensions or changes of the frequency coverage can be discussed, but this must be agreed upon before ordering. In any case, this is not the producer's obligation and can not go against local rules and laws. However, the purchase of an unrestricted HF amplifier must be made by a Government agency directly from some of our authorized dealers or by us.

The most used codes, terms, and abbreviations in amateur radio practice can be found in this guide.

Download article | PDF file