I’ve been thinking about the Alpha 9500 a lot lately, given that I have one in my shack.
I’m very happy with RF Concepts (just “Alpha” to me, for some reason) and the 9500. I’d like to have something to add to impressions that are already out there. Unfortunately, my impression is pretty consistent with the many good reviews I’ve found, both before and after purchasing. Since I am not trying to be comprehensive, I’d also recommend you check out the helpful resources on the Alpha 9500 at dxzone.
I considered alternatives from Expert Amps, THP, Acom, Icom, Ameritron, and a few others. I also have an Ameritron AL-80B. I’m happy with the AL-80B, but wanted full legal power and, more importantly, the ability to operate remotely. I think the 9500 is a clear contender for the best amp on the market. I think the AL80B is a very good value in decent quality watts/dollar and excels in that niche.
Rather than repeat a hundred posts and sites on the features of the amp, I will share some of my decision factors and thinking. The Alpha 9500 Group on Yahoo is also helpful.
My key considerations were:
- Bands: 160-10 (I don’t do 160 now, but if I ever do), and my usage pattern rarely aligns with 6 meter openings, so that’s not a factor for me.
- Auto bandswitch and tuning, allowing me to run QRO remotely, I’ve also found the convenience compared to manual tuning is a nice plus, my usage so far is almost entirely from the shack.
- Robustness and match flexibility. I have mostly resonant/matched antennas. However, I didn’t want to be constrained to near perfect match conditions. Amps that tolerate 3:1 or included a QRO tuner were all that I considered.
- Full legal limit output, with reasonable headroom
- Sound/Size/Form factor/etc were considerations, but not as strong as the above
- Made in America – A nice plus compared to some of the alternatives
I was torn between tube based and transistor finals. The start up time, longevity/availability, signal clarity/efficiency, were all part of this. Transistors win on start time, and maybe longevity, but lose slightly on signal clarity/efficiency. Just to clarify, I think the engineering limits of signal quality and performance are similar, but practical amateur amps have better signal performance (e.g., lower IMD) when tube based. After a lot of thought, I came to the conclusion that transistor devices and availability change almost as fast, or maybe faster, than surviving power tubes. The obsolescence risk wasn’t really that much better with transistors. You run some risk with either choice. The alpha is designed around the 8877 tube, which is still in common use and available from multiple manufacturers. On this front, the fact than an 8877 can dissipate 1500 watts continuously won my mind. The comparable transistor amps I considered run much closer to the device design in terms of power dissipation. I’m not knocking them, but they don’t have anywhere near the headroom.
I do prefer active control/signalling of the band and frequency to the auto-sense behavior of the Alpha 9500. The active signaling approach allows the amp to perform band-switch and frequency adjustments without transmit power present, since frequency and band changes normally occur in receive mode (always for me, not sure about others). In the end, the other benefits of the 9500 outweighed this preference. Of course, my preference is on the margin, as there are benefits to each approach. The auto sensing on the Alpha works 100% for me so far. My preference is more conceptual than practical. Since band changes can be requested from the software interface through the 9500 control application or the documented commands, I might explore supplementing the auto-sensing with pro-active commands to set band in the future. Separately, the integrated 4 port antenna switch is nice to have, though I only use one port at this time. I will be using distinct ports for some bands soon.
I believe both the main cooling fan and the tube chimney fan are two speed. Although they kick up from time to time, clearly the amp just loafs at 1500 watts. I worry about my antenna system handling the power, but never the amp. I’m mostly SSB, so there is even more headroom. The amp has no problem at all with 1500 watts continuous RTTY or any other mode.
As you can see, in the end I chose the 9500 and am happy with it. It’s a high end, high power amp, at a fair, but premium price. In my opinion, its worth it.
73 and Good DX.
Dan Hoogterp, W4LI