Discussion in 'Amateur Radio Amplifiers' started by KM6VVW, Mar 5, 2019.
And I lived in the East Bay Area for three years before moving to Vermont. Parallel paths...
No, that portion of 75M is still consider RTTY territory by DX stations, even though USA hams don't have access to it for data. You can hear Europeans there during RTTY contests.
75m "DX window" has been 3790-3800 as long as I can remember, and I think it still is.
The Ameritron AL-811H is all the amp you need and will operate off of 15 amps @ 120 volts. Produces 600 watts PEP out. Enough 120 volt current left for your radio shack power supply too.
At around 50% efficiency in Class AB at 30 MHz...
600 / 0.5 = 1200W PEP input.
The HV PS is probably 90% efficient (mostly magnetic losses). That puts us at 1200 / 0.9 = 1333W.
Add filament power (6.3V @ 4A each or ≈ 25W): 1333 + 100 = 1433W.
Then, I = P / E = 1433/120 = 12A
Keep in mind that human speech ≈ 25% duty cycle, and Morse ≈ 33%. The AVERAGE current is much less than the peak value. Anode efficiency improves at lower frequencies, to as good as about 60%, further reducing the AC current.
If you keep your tune ups (full power) short the AL-80B will work fine on 120V. I have run one through a power strip with a built in 15A breaker (20A circuit, which actually has 12 AWG copper wiring) and only ever tripped the breaker in the power strip after mutiple tune ups (like chasing DX around the band).
Of course it is much easier to extinguish a fire in a power strip than one in your wall. So if your wiring can really only handle 15A this may not be a good approach.
However, the AL-80B is a much better amp than those 811 jobbies. The 3-500Z is much more rugged and better for someone new to amps. 811A tubes and sweep tubes are a poor choice for someone new to amps.
I agree, there's a rather huge difference.
Plus, the AL-80B has a built-in true PEP wattmeter/SWR meter which the 811 models don't have. And the single tube (not 3 or 4) generally lasts about 10 years in frequent service, but if it should fail, it's "just one" throat to choke.
I've never had one "fail," but have seen them degrade with age -- in any kind of amp.
House was built in 78, I believe the wire is 12G copper wire on the 15A upstairs circuit.
Not saying you have reservations using a 15 amp CB. But, reason I know the AL-811, a 60 watt table lamp (not LED) and an Astron RS-20 running a HF transceiver and 2 meter FM transceiver works on 15 amps is that is what I have and never tripped the circuit breaker. My AL-811, not H model has 3x 572B and produces 800 PEP out. The extra 811A tube using 25 watts RMS filament is still likely a little less 120 volt current draw compared to my amp at 800 watts PEP out vs an AL-811H with 600 watts PEP out. The suggested AL-811H with 811A tubes was mentioned to be used at 600 watts PEP, not the factory exaggerated higher rating at 800 watts PEP out due to the fragile 811A tubes,
Transformer and HV rectifier losses are about 5% IMO. I would also think the AL-811H amp average current is about 10 amps with speech processor on and using SSB. The 15 amp circuit breaker monitors average current vs peak current and amp use is about 50% duty cycle, less in a round table.
As for the AL-80B, it should not draw more power at 600 watts PEP out vs the AL-811H. But, I heard the AL-80B can run close to 1K PEP out and that may trip the 15 amp circuit breaker with an Astron power supply.
A used AL-811 ($450 average cost) with three new 572B replacement tubes at a cost around $200 is less expensive vs a used AL-80B amplifier ($900 average cost).