[TowerTalk] Power-meters

José de Sá ct1eeb@mail.telepac.pt
Mon, 9 Nov 1998 11:55:13 -0000

Sometime ago I have send a question out in this
Mailing list about Power-Meters.
Several of you asked me to post a resumee of my 
findings (replies) again in Towertalk, so here they are:

My question was:
> Hello,
> I have been using a Yaesu YS-60 Power-meter but recently
> when transmitting on RTTY high-power with the Ameritron AL-1500
> the Power-meter went crazy in its measures and never returned
> to normal....
> Will any of you in the list advice me of a good Power-meter that
> can stand at least 1500 watt RMS in RTTY !!!!
> I will probably have to purchase a better meter rather than the YS-60.
> Best regards,
José  CT1EEB

The answers:

Bird 43 with a 2500 watt slug.  $$$$ but they work.

You could try the P-3000 digital watt meter manufactured by RF
Applications.  HRO and AES carry it but the price at HRO is MUCH
cheaper.   73  Reggie (AA3LR)


I haven't got an amp that puts out 1500 w for very long on RTTY but it
does put out 1500+ watts on tune.  I have an Autek WM-1.  It has a 2000
watt full scale and hasn't failed yet during tune ups at the 1500 watt
level.  Dunno what a 1500W RTTY  contest would do to it though.

Contest season is almost here.

Good luck.

73 de Brian/K3KO

By the way all wattmeters I've recently seen (excluding Bird) use a
current sense transformer and depend upon some kind of calibration to
get the readings to be OK.
In reality, the readings can vary a lot from reality depending upon the
band and impedance the wattmeter sees.  I find that I only believe the
wattmeter reading when it agrees with a calculation of ouput done from

Power out = plate current x plate current x amp efficiency

I've seen readings from the "wattmeter" in my amplifier imply an
efficiency >100% under certain conditions!
If the wattmeter is implying an efficiency >70% it is reading too high.
Vance Net Inc
End Of Message 


I beleive one of the best compromises between tolerances, functionality
and power ratings is the Daiwa CN-660PA model. This model is handling
30-300-3000W ) with very acceptable tolerances on AVG & PEP and has a
head option with extended frequency range. Bird is more accurate but his
functionality is problematic and is much expensive.

73 de Morel, 4X1AD 


ask for Drake Or Collins directional couplers.

73 de oa4cvt

Hi José:

I have several different wattmeters. Some cheaper ones and one (RF
Applications)is possibly the most expensive around $300 U.S. I

For the money I think the Autek WM-1 "computing" two meter, peak or
average, 20/200/2000 scales, is the best value. Plus it has a remote pickup
so you can place the meter where you want. The only downside is that it
requires AC power. $199 U.S. I think.

Otherwise, most of the single meter analog wattmeters are somewhat
alike. I think the ARRL did a wattmeter comparison sometime ago. None
seemed to have a clear advantage. They may be cheaper than the two
meter or cross needle units. I personally think the two meter
or cross needle units are the only ones worth getting.

Don't buy the Radio Shack digital unit (probably not available
anymore anyway).

Good Luck,

Aloha, 73

Kimo Chun,  KH7U

Daiwa CN-660a No longer available and they do not make
              any for over 1500 watts that are offered here.

Diamond FX100 - 3000 watts is  $129.95

Bird 43 P - Peak reading   $359.95
     43   - no peak reading  $249.95
  2500 W slug - $119.95

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