Specifications

mode switch to “Operate” and continue with the contact. It is very nice not to have to
worry about tuning the amplifier when I need to transmit. As all of my antennas are
resonant in the band segment I’m interested in (CW end of the HF bands), high SWR
isn’t a problem. For the rare occasions when I move out of the CW bands, I use a MFJ-
994B auto-tuner to instantly trim the SWR. The MFJ-994B also controls a modified
ARB-704 which takes the ALS-600 off-line automatically whenever the MFJ -994B starts
tuning (info in the “Equipment Modifications” section of this website).
And incidentally, I can vouch for the robustness of the amplifier and the operation of the
protection circuitry. I’ve accidentally transmitted into a disconnected antenna or
transmitted with the amplifier band switch in the wrong position more times than I’d care
to admit!
QSK Modification
Unfortunately the ALS-600 is not QSK compatible. This is a problem for me as a CW
operator because I find QSK almost a necessity when working DX pile-ups. The open-
frame T/R relay has a 13ms enable time which relegates you to semi break-in CW or
manual keying of the amplifier using MOX . Of course, this just wouldn’t do. As some
of you know, I am not hesitant about modifying equipment. So it was only a matter of
time before I modified the amplifier for QSK operation. The QSK modification consists
of replacing the existing open-frame T/R relay with a printed-circuit board assembly
containing a pair of high-speed telecom relays. Details of this modification can be found
in the “Equipment Modifications” section of this website.
Conclusion
If you need a little extra oomph to break that pile-up or help combat the poor conditions
due to the current sunspot cycle, you might consider the compact ALS-600M solid-state
amplifier from Ameritron. The price and features make this an amplifier that will fit
many budgets and operating locations.