Some equipment changes – I’ve got a new amplifier

Long term readers will remember that in November 2011 I bought myself an Acom 1000 amplifier and that really was a super piece of equipment. It served me faultlessly and worked without any issues whatsoever. It alerted me a few times to aerial faults but just soldiered on and on and on.

Over time, there were three things I liked less about it. The first one was the three minute warm up time after switching it on and having to retune when I changed bands, or even when I QSYd around in the same band. I marked the dials and managed to get the retune down to just a few seconds but I still had to do it. Times have moved on, I don’t want to have to do that any more. Finally, when I first got the Acom, I had one HF aerials. Now I have three HF aerials and the Acom only has one aerial connector.

A few months ago I started looking at alternatives. While operating DXPeditions and Special Event Stations, I’ve used a handful of different amplifiers but most recently, the SPE Expert 1K-FA. This is a solid state amplifier, capable of delivering 1KW, weighing 44lb and with a built in ATU. They’ve always worked relatively well for the Martello Tower Group both in Herm and onboard Ross Revenge. I borrowed one earlier this year but one thing struck me. The fans. They run from the moment it’s switched on and after a few overs of FT8 or CQs during a RTTY contest, they reached ear bleeding level very quickly. Apart from anything else, the Expert 1K-FA is no longer in production.

SPE currently produce three amplifiers, the Expert 1.3K-FA, the Expert 1.5K-FA and the Expert 2K-FA. I asked a few questions on an SPE Amplifiers email group and based on the answers, I decided to go with the Expert 1.5K-FA with full CAT control from my radio. I kept an eye on stock for many months as they simply weren’t available and then suddenly they were showing in stock. I called and paid my deposit instantly and then a few weeks later collected not just a new amplifier but a new headset as well. There’s nothing wrong with my old Heil Pro Set Plus except that it’s a bit tight over my head. I bought a Radiosport RS60CF headset which is more comfortable to use for extended periods of time.

I’ve only briefly used the headset to listen so far and therefore I’ve not set up the audio levels on the wireless yet but I’m happy to report that it’s more comfortable than the Heil. It has a larger range of adjustment and because the headband is metal, it’s possible to bend it slightly to make it tighter or looser, depending on what’s needed.

Going back to the amplifier, it’s not completely quiet and anyone who says that it’s ‘whisper quiet’ is telling porkies. The fans have multiple levels and the 1.5K-FA is significantly quieter than the 1.5K-FA. When the amp is in standby, if the temperature is below a certain level, the fans aren’t even spinning. Take it out of standby and they come on a level that really is almost inaudible and they just kick in while transmitting. I’m running it at a similar power level to the 1K I borrowed and it’s definitely quieter. At around 23lb, it’s a lot lighter than the older model as well.

The Expert 1.5K-FA has three power levels, these are Low, Mid and High and when the amplifier is connected via a digital interface cable from the wireless, those power levels are controlled by the amplifier to be 500W, 1.0KW and 1.5KW. I bought the appropriate cable from Billy at Hamcables and his service was impeccable. Super quick and really well made. I can’t recommend him highly enough. He also sent me the extra cable I needed for the foot switch for my new headset. Thanks Billy!

With this cable between the amplifier and the radio, there’s no need to adjust the output power on the amp, it’s all dealt with automatically via the ALC line. The amplifier effectively tells the radio to reduce the output power down to the correct level to give the correct amount of output power. Band changes are handled automatically as well, no need to blip the transmitter to change band, it knows the band and frequency the radio is tuned to and sets itself up appropriately.

When I first got my Acom, I worked out how much power I needed to run on each HF band in order to get 400W at the aerial and taking into account coax length, coax loss and connectors, it was around 500W and so the Low power setting on the Expert is exactly the correct level for me to give out full legal limit. I’ll be running this amplifier the same way I used the Acom, with the correct input to give me legal output. That way I won’t be stressing the output device and will make it last as long as possible. I have tried it briefly on medium and high power into a dummy load and it’s a little scary for a UK radio amateur to see 1.0KW and 1.5KW on the display.

I can’t stress how easy this amp is to use, switch it on, switch it to operate and transmit. It’s as simple as that. It has a built in ATU and although all my aerials are resonant, I went through the process of teaching the amp about the aerials that are connected so that it always knows what setting the tuner should be at. As far as amplifiers go, this has to be one of the most simple to set up and use. It even sends 73 in Morse when you switch it off.

SPE Expert 1.5K-FA at G6NHU

I made a post in 2017 describing the effects of increasing output power which is well worth a read and will demonstrate why I’m happy to tick along at the full UK output with no desire to run this amp at full output.

When I wear the headset, I feel like I’m standing on the pit wall, watching an F1 race.

Radiosport RS60CF headset

It’s always nice to add new equipment to the shack and these two items will be well used. I may only use the headset a few times of the year but if it makes contesting more comfortable then it can only be a big thing. I’m already benefitting from the additional features that the Expert is giving me over the Acom, apart from instant-on and no-tune, I can now operate over the whole of 40m due to the built in ATU and even better, I can have all my aerials connected at the same time with no need to switch anything when wanting to use 30m or 40m.

I have nothing against the Acom and was seriously considering replacing the Acom 1000 with an Acom 1500 but the additional features of the Expert just tipped me in that direction. I just hope it works as well for me as the Acom.

Leave a Reply

This site uses Akismet to reduce spam. Learn how your comment data is processed.