23 Dec 2012

FT817 "power blobs" question

Having owned my FT817 (original version, not ND) for nearly 12 years I am almost too embarrassed to ask this question now.
http://upload.wikimedia.org/wikipedia/commons/5/55/Yaesu_FT-817_(1).jpg
When checking an old Bird RF power meter today I measured the power of my FT817 on and off a PSU at all power level settings. All these years I had assumed that "3 blobs" on the screen (when on a PSU) meant that I was putting out 5W. What I measured was closer to 2.5W. This did not change when the PSU was disconnected: still 2.5W. Then I pressed the button to "no blobs" and the power went up several dB, to I assume a nominal 5W. When on batteries it was "blinking 3 blobs". having re-read the FT817 (original) manual I was none the wiser: it does not mention a "no blobs" setting.

I think all these years when I had assumed my DX was being worked with 5W I was actually using just 2.5W. It looks like I should have gone to the "no blobs" setting with a PSU to get the full 5W.

So, can someone please clarify what power the FT817 should produce at all the different "blob" settings on batteries and on a 13.8V PSU?

UPDATE: I have the answer from Pete M3KXZ

Hi Roger.

On PSU:
- no blobs, output is 5W
- 3 blobs, 2.5W
- 2 blobs, 1W
- 1 blob, 0.5W

On internal batteries, the radio will default to "L///" and output 2.5W. If you
select high power, you will get 5W with "///" blinking. The other blobs are same
as for PSU.

I always run off external battery pack and the max power setting shows no blobs,
until the voltage starts to drop a bit when it automatically goes to "///"
blinking.


Well I'll be damned!  So for 12 years nearly I've been running 3dB less than I thought.

6 comments:

Dick said...

Those little vertical lines at the bottom of the display are difficult to read.

You have really been doing better than you thought all these years. Nice compliment to your operating skills and antenna effectiveness.

Bert, PA1B said...

Hello Roger, it also means that the QSO's with 2.5 watts to the USA are all good for 1000 Miles per Watt

Roger G3XBM said...

It also means I worked the USA on 6m CW with just over 1W ERP a few years back. I am still dumbfounded that I had the power wrong all these years. At least the FT817 PAs have never been stressed at full power!

aa7ee said...

As the others said - you have been doing better than you thought! I had the same problem with my FT-817 - was regularly checking the manual to remind myself what the power bars meant. I guess it's one of those things on that little rig that isn't intuitive.

Dave
AA7EE

W7DTG said...

So does that mean if you had NO blob's you could have worked twice the DX...lol
Great site, look forward to more from you.
be sure to take a look at my Blog over at w7dtg.blogspot.com and feel free to share it.
thanks and 73 Don

Jspiker said...

I wonder how accurate the readings are on my IC 703 internal meter. I've never hooked up a "good" power meter but according to my external tuner, the output always shows much less. At times, I'm only running 2 1/2 watts into a random wire? I continue to be amazed the distance very low power can work.