Planning an upgrade to my 70cm EME station and evaluating amplifier options. Currently running 100W from my TS-2000 into a 4x19-element array with a 1KW SSPA amplifier which is driven by a FlexRadio 6600 series radio setup I've seen at remote stations. An 80W 70 cm (432 MHz) setup using about a 12-15 dBi Yagi works well for EME Moonbounce communication using digital modes like the JT65, but I'm looking at serious power upgrades.

Considering either a 1KW SSPA or going with a tube amplifier. The SSPA offers better reliability and cooler operation, but tube amps might be more cost-effective for high power EME work. It is heard that about 1500 Watts of output is needed for an SSB QSO though most of my work will be digital modes. To overcome the losses and enable amateur radio radio communications to be established using Moonbounce, very high radio transmitter powers, directive antennas and very sensitive receivers are required.

Anyone have experience comparing modern SSPA reliability vs tube amps for 432 MHz EME duty cycles?

I've been running a 1.2KW SSPA on 432 for three years now with excellent reliability. The duty cycle advantages are huge for digital modes - no warm-up time, instant on/off, and much better spectral purity than most tube amps. Initial cost is higher but operational costs are lower, especially if you're doing serious contest weekends.

Tube amplifiers still have their place, especially for budget-conscious ops. A well-maintained 3CX800 or 4CX800 can provide reliable 1KW+ output at a fraction of SSPA cost. However, consider the cooling requirements and potential RFI issues. For EME work where you might be transmitting for hours during moonrise/moonset windows, thermal management becomes critical.

Both have merits, but don't underestimate what you can accomplish with your current setup. I've worked over 100 DXCC entities on 432 EME with just 400W and a modest array. Focus on optimizing your receive system first - install a low noise preamplifier with 0.5-0.8 dB NF at the antenna input point if you haven't already. The moon doesn't care about your amplifier brand!