[AMPS] AL-1500, poor efficiency

[Chartec Laboratories A/S]

I have an new AL-1500 amplifier which doesn't perform very good on 14 and 21MHz.
Especially on 14MHz the efficiency is low.
I have already asked Ameritron to get their opinion, but they just say that
the plate should be minimum 3,2KV at full load and there should be 2KW out.
How I can obtain 3,2KV at full load without changing the transformer I don't
know!

Do anyone else have the same phenomenon with poor efficiency. Maybe Ameritron
have made a tradeoff in the tank-circuit between WARC-bands and traditional
bands which could compromise the performance.

Below I have listed all values I acheived in a test setup.

I would be greatful if anyone know what the problem is or could tell me if this
is "normal". My expectations went much further.....

73 de Soeren, OZ1FTU (OZ5W)

mailto:soeren_pedersen@chartec.dk

Measurement on Ameritron AL-1500						

The amplifier is tested on a dummyload and output power (CW) is measured
with a Bird 43 and 1000H slug.
Plate voltage and current are measured with built-in meters in AL-1500.

Freq.	Ua	Ia	Igrid	Pout	Drive	Load	Input	Eff.
MHz	Volt	Amp.	mA	Watt	Watt	dial	Watt	%

1.83	3000	0.630	10	1000	32	2.6	1890	52.9
1.83	2900	0.900	115	1500	75	4	2610	57.5

3.65	3050	0.500	15	1000	30	3	1525	65.6
3.65	2850	0.925	65	1750	75	6.5	2636	66.4

7.05	3000	0.600	10	1000		1	1800	55.6
7.05	2850	0.950	65	1700	75	3.2	2708	62.8

10.13	2950	0.725	10	1000		0	2139	46.8
10.13	2800	0.975	65	1700	80	1	2730	62.3

14.20	2950	0.675	20	1000		4.8	1991	50.2
14.20	2750	1.040	75	1400	55	5.5	2860	49.0
14.20	2750	1+	80	1700	75	6	3438	49.5

18.13	2950	0.675	15	1000		3.8	1991	50.2
18.13	2850	1.000	35	1250	65	5	2850	43.9
18.13	2800	1+	60	1500	80	5	3360	44.6

21.22	3000	0.625	30	1000		5.6	1875	53.3
21.22	2850	1.000	50	1500	60	5	2850	52.6

24.90	3000	0.630	15	1000		6.4	1890	52.9
24.90	2850	1.000	90	1300	75	7	2850	45.6

28.50	3000	0.630	20	1000		7.4	1890	52.9
28.50	2850	1.000	75	1600	80	8	2850	56.1

--
FAQ on WWW:               http://www.contesting.com/ampfaq.html
Submissions:              amps@contesting.com
Administrative requests:  amps-REQUEST@contesting.com
Problems:                 owner-amps@contesting.com
Search:                   http://www.contesting.com/km9p/search.htm