[TenTec] Centurian data points.

[Bob D.]

Hi Carter,
I'm more inclined to suspect a resistor, cap, or connection  in the
metering circuit than the load.
I should have a new fan here in a week and will find and fix the other
stuff while the cover is off.
Tubes? I found some new ones for $150/each. Gotta buy 12. Don't need 12. I
may have a pair
of good 3-400Z around here somewhere.
73, -Bob ah7i


On Wed, Feb 24, 2021 at 1:48 PM <W3HKK at roadrunner.com> wrote:

> My Vectronics DL2500 fan cooled DL seems very stable  when tuning up on
> 160-6m.
>
> -----------------------------------------
> From: "CARTER GRABARCZYK"
> To: "ah7i at gatech.edu", "Discussion of Ten-Tec Equipment"
> Cc:
> Sent: Wednesday February 24 2021 10:30:13AM
> Subject: Re: [TenTec] Centurian data points.
>
> What kind of dummy load? An off the wall idea, but when the "dummy load
> gets very warm", is it still 50 ohms - or is the resistance changing?
> 73,Carter   K8VT
>
> On Tuesday, February 23, 2021, 2:00:25 PM EST, Ken Brown <
> kenradiobrown at gmail.com> wrote:
>
> Hi Bob,
>
>     Not sure exactly where your numbers are coming from. Is Pin your
> calculated Plate Power input using Plate Current and Plate Voltage meter
> readings from the amplifier? How are you measuring fwdWatts? The built in
> meter in the amplifier? Are you using any kind of RF wattmeter separate
> from the amplifier, such as a Bird 43 with a 2500H element? You mentioned
> an RF Voltmeter, have you used that yet. What kind of RF Voltmeter is it?
> Do you trust it's accuracy and flat frequency response on all of the HF
> bands? And is it high enough impedance to have negligible effect on the 50
> Ohm  system? If so measuring RF Volts directly at a good 50 Ohm
> non-inductive termination should be a good way to accurately determine RF
> power.
>
> Ken N6KB
>
> On Tue, Feb 23, 2021 at 7:48 AM Bob D. <ajamas.rn at gmail.com> wrote:
>
> > New to me Centurian.
> > I was a bit surprised to find a 15A and a 25A fuse.
> > 20 A x 2 is specified for 230V so I replaced them.
> > Total is the same :-)
> >
> > Here is what I see with a 50 Ohm dummy load and the Centurians meters.
> > The LED peak reading varied from 1.2 * to 2 * the "wd" meter.
> > Drive varies from 50 W to 100 W with lower on the higher bands.
> > Drive is Eagle via 18" coax and a 6' piece of RG213 to the dummy load.
> >
> > Band(CW end) m, Ig mA, Ip mA, fwd Watts?, Pin
> > 10 260 390 600 1100
> > 15 260 430 900 1200
> > 20 230 420 1100 1180
> > 40 200 500 1200 1400
> > 80 230 600 1200 1700
> > 160 250 600 900 1700
> >  Ep 2.8 kV at 600 mA
> >
> > Things don't add up.
> > 10 m 1100 W in 600 W out is not unreasonable
> > 15 m 1200 in and 900 out seems rather good but not impossible.
> > 20 m 1180 in and 1100 out is nonsense
> > 40 m 1400 in and 1200 out is  unbelievable
> > 80 m 1700 in 1200 out is not unreasonable
> > 160 m 1700 in and 900 out is a bit low but how efficient is this amp on
> > 160?
> >
> > Yes, the dummy load gets very warm.
> > Anodes glow nicely on 10 m so the input power is going somewhere :-)
> >
> > I suppose I'm going to have to dig out and check calibration on my RF
> > voltmeter and measure at the dummy load to have a good number for the
> > output. Will also have to study up on the metering circuitry to see why
> the
> > results are so weird.
> >
> > The manual says no more than 800 mA Ip. They must have used a different
> > transformer to get 800 mA!
> >
> > 73, -Bob ah7i
> >
> >
> > -do not look into LASER with remaining eye!
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> > TenTec at contesting.com
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> /> >
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-- 
-do not look into LASER with remaining eye!