Discussion in 'General Announcements' started by K1KP, Apr 17, 2019.
per the previous post and doing a little math, 750W/120 VAC = 6.25 A (RMS ) for peak output...
Assuming Power Factor = 1.0
Which it rarely is with switching power supplies.
Also, per that previous post:
"A conservative estimate of power line consumption would be <750W in transmit, and probably <20W in standby." (Red, underlined text for emphasis)
It's safe to assume these easily measured values haven't been measured. Why not?
In the real world we would put an amp meter on it. Please do that and let us know.
Yes, we know it is a transmitter not just an amplifier, but we do want to know the total amp draw at 500W output key down.
So, I'm very focused on the efficiency of the PA, and I have literally thousands of measurements of DC power in vs RF power out. The transmitter is my area of contribution; the power supplies, not so much.
The Polar Explorer uses two 350W off-the-shelf switching supplies to supply the DC for the PA. They are spec'ed at 89% efficiency, and of course being switchers the power factor is not wonderful. But with 89% efficiency their real input power should be in the range of the 750W number I listed.
I have a TEK 2645B scope and an HP 3585A Spectrum Analyzer, but do not own the instrumentation needed to accurately measure real AC power...
Why is that such a concern? It's significantly less than the Elecraft KPA500, or the AL-811...
A $75 clamp on amp meter will get you in the ballpark.
How do you know it is significantly less than a KPA500 or AL-811 if you haven't measured yours?
WN1MB asked a very on point question about why very easily measured values haven't been and why. Please address that question also. Please, please, please convince us that this is not just wishful thinking and smoke and mirrors.
By whom? The manufacturer? (we all know manufacturers don't fudge or lie...) Has that efficiency figure been confirmed?
If 89% efficiency has been confirmed, then yes, it should be - but is it?
And what range of the 750W number? +20%/-5%?
...without measurement. mkay...
I'm not trying to beat anyone up here. Though it may appear as picking nits, words do matter. Weakly substantiated claims draw a discerning eye and arouse suspicion.
Why do I want a transmitter only nowadays???? I want everything in one box and it's called a "Tansceiver". Miss spell!
No it isn't. It's call a "Transceiver".
That's a great question!
The Polar Explorer project is intended to bring high efficiency transmitter design to the HF amateur market. My contribution is in the area of transmit technology, not receiver or user interface design. This means that the quickest and most efficient path for me was to design this as a 'companion transmitter' that works with existing transceivers. I could have spent another year or two adding a receiver and full front panel, but that's not where my value added lies.
If you want 500W in a single box, there is no such solution in today's market. But there could be, if a future implementation of Polar Explorer technology was combined with a receiver to make a one-box, 500W Transceiver!
Any ham that already has a transceiver (and that includes low power QRP rigs that can't drive a linear to 500W output) with a computer interface can move to the 500W power level by adding the Polar Explorer. The existing transceiver is used for control and receive functions. The audio from the transceiver is routed through the Polar Explorer so the usual transmit related audio functions can be handled, such as CW Sidetone, TX monitor, and Tx muting.
The price point for a product version would therefore need to be competitive with a commercially available 500W amplifier. The Elecraft KPA500 is a very popular 500W amplifier and is priced at $2300 so that leaves room to be competitive.