swr goes up when amp is used

[295]

I am confused now! sorry, I need to key the amp to see the high swr jump that is not there without power. so then the mfj will show the high swr and I can adjust the slug? If the rig is in ssb and mic disconnected then the rig cant key and excite the amp.

Forget the analyser. Do it the way before the MFJ 259 existed. Use you radio to key the amplifier. This is what you want in line. Radio - SWR Meter- Amplifier-Dummy Load.

Put your radio on 10 meter CW, adjust the drive from the radio to about 10 watts. Tune up the amplifier for max output, adjust the slug for lowest SWR, confirm that the amp is in tune, do one last tweak on the slug. Now increase the drive to 35 watts, repeat the proceedure, now increase the drive to 75 watts (or whatever is the max input drive rating of the amp) and repeat the proceedure to obtain the lowest SWR at max drive/output.

73

 

[Beetle]

You will absolutely need a good dummy load for the amplifier. Connect the transceiver and a good SWR meter in the usual way. Tune and adjust the amplifier for the favored part of the band you're working on, using the dummy load.

Key the transmitter using CW (unmodulated signal). Adjust the slug for lowest SWR. Remember that some of the input circuitry is shared by two bands. If you adjust to improve one band, you'll throw the other band off. Your call as to which one you want to favor.

 

[airplane1]

I don`t have a dummy load that high wattage. I think an operator near me does though.

I will let you all know when I get this done. It is funny that swr goes up when amp is running but on standby it is good.

Now can someone please tell me what the Z reading is for on the mfj259? I want to learn how it works. Or should I start a new post else where?

AP

 

[295]

I don`t have a dummy load that high wattage. I think an operator near me does though.

I will let you all know when I get this done. It is funny that swr goes up when amp is running but on standby it is good.

Now can someone please tell me what the Z reading is for on the mfj259? I want to learn how it works. Or should I start a new post else where?

AP

Not funny at all, when the amp is on stand by the input circuit and amplifer is bypassed and your RF is put straight through to the antenna.

73

 

[Beetle]

Now can someone please tell me what the Z reading is for on the mfj259? I want to learn how it works. Or should I start a new post else where?
AP

Z always represents impedance. X=reactance, R=resistance. The vector sum of X and R = Z.

Do you have the operator's manual for the 259B? It should have all that information in there (mine does). If you didn't get a copy of the manual, download it and print it from the MFJ website.

 

[airplane1]

I have the MFJ-259 not the B version. I have the manual but got to look again as I dont remember it saying much.

I know it just shows SWR,Z and gate.

Thanks,
AP

 

[Beetle]

Ah! You have an oldie. But, "Z" is still "impedance". You might find some helpful information with the 259B manual, though.