Hardrock-500 LPF

[Maurizio Brameri]

Hi, I was able to measure the LPF filter response and on my knowledge it seems they are ok.

I put images of my scans.

160 m

80 m

60 m

40 and 30 m

20 and 17 m

15, 13 and 10 m

You see that the difference between 20 m (about -1 dB) and 10 m (1.2 dB) is low, but on 20 m I have 160 W out and in 10 m I have 225 W out, similar to 13, 15, 17, 10 and 7 MHz.

Any suggestion?

Best 73s,

Maurizio I2NOY

[jcve...@gmail.com]

Hi Maurizio,

Thanks for posting the filter plots and it look like everything is OK with the filters. The amp has different gain at different frequencies and can depend on many factors. I need more information to make recomendations.

With 5-6W of drive how much power do you get on 20M? 

What kind of radio are you driving the amp with?

What are you using to measure the output power?

What kind of load are you using?

73,

Jim WA2EUJ

[Maurizio Brameri]

Hi Jim, here my replies.

I am driving the amplifier with an Elecraft K4

The power is measured with a Smorf wattmeter 2 years old. It is made by MicroHam

I tested with a MFJ-264 dummy load, declared from 0 to 650 MHz and 1.5 kW.

I tested also with my antennas (max SWR 1:1.3) without any tuner and I obtained the same results.

Best 73s,

Maurizio I2NOY

[jcve...@gmail.com]

Hi Maurizio,

I am a little confused as to the problem you are having. With up to 6W drive, does the amp generate at least 300W on 160, 400W on 80-12M and 350 on 10M? If so the amp is working fine. If not I would recommend winding T3 with the correct coax cable instead of the smaller RG316-25.

If you are concerned that the amp has different gain on different bands, that's normal and could be made worse by changing the output transformer. Transformers are part of the secret-sauce of an amplifier; any changes can have a large effect on the characteristics of the amp.

73,

Jim WA2EUJ

[Maurizio Brameri]

here my measures of few minutes ago:

160 m       300 W with 2.5 W in         (OK)

80 m         480 W with 4 W in            (OK)

60 m         385 W with 6 W in            (near to be OK)

40 m         396 W with 6 W in            (rather OK)

30 m         415 W with 5.5 W in         (OK)

20 m         300 W with 6 W in            (NOT OK)

17 m         410 W with 5.5 W in         (OK)

15 m         410 W with 6 W in            (OK)

12 m         425 W with 6 W in            (OK)

10 m         312 W with 6 W in            (not OK)

Probably the RG-316 25 ohm is not the right cable.

73

Maurizio I2NOY