Amp and SWR issues

[cecil]

Ok, so I am experiencing some high swr readings with the amp in place. Here is what I have for a base setup:
Grant LT dead key 1w, swings 12 or so.
RM Italy 203P, new
Max 2000 antenna, new this year.
RG213 coax, new this year.
(2) 3' RG8x jumpers, checked continuity, ok.
Dosy meter, works fine as I know it.
With setup without amp, I get swr of 1.1 on Chan. 1 and 1.05 on Chan. 40
With amp in place, I get swr of 2.3 on Chan. 1 and 1.7 on Chan. 40
I checked this twice, maybe more. All connections are tight. I have got good reports on the Grant without the amp, so wondering what is going on here. I do not have a antenna analyser. Hesitant to use amp with reading this high.
Would a low pass filter inline with amp to meter help lower swr?

[jessejamesdallas]

Could be power supply not strong enough to run everything at once...or something just needs a better ground...I would suspect the amp...Might try just running a ground wire off a screw on the side of the amp somewhere to a good grounding point and see if there's any change.

Try running to the screw that holds the cover onto the electrical socket...If there's any change, then maybe run the ground wire to a better grounding point.

[cecil]

Appreciate your input...something to try for sure with grounding wire.
There should be plenty of amps to power everything. Last month I bought a Mega Watts supply here from a sponsor. The 50 amp one! Room to grow

[Bozo]

Appreciate your input...something to try for sure with grounding wire.
There should be plenty of amps to power everything. Last month I bought a Mega Watts supply here from a sponsor. The 50 amp one! Room to grow

Congrats, [mention]cecil[/mention]! Always room to grow and pump it up more... Put some more fire in the wire! LOL

[cecil]

Appreciate your input...something to try for sure with grounding wire.
There should be plenty of amps to power everything. Last month I bought a Mega Watts supply here from a sponsor. The 50 amp one! Room to grow

Congrats, @cecil! Always room to grow and pump it up more... Put some more fire in the wire! LOL

!!

[MDYoungblood]

Ok, so I am experiencing some high swr readings with the amp in place. Here is what I have for a base setup:
Grant LT dead key 1w, swings 12 or so.
RM Italy 203P, new
Max 2000 antenna, new this year.
RG213 coax, new this year.
(2) 3' RG8x jumpers, checked continuity, ok.
Dosy meter, works fine as I know it.
With setup without amp, I get swr of 1.1 on Chan. 1 and 1.05 on Chan. 40
With amp in place, I get swr of 2.3 on Chan. 1 and 1.7 on Chan. 40
I checked this twice, maybe more. All connections are tight. I have got good reports on the Grant without the amp, so wondering what is going on here. I do not have a antenna analyser. Hesitant to use amp with reading this high.
Would a low pass filter inline with amp to meter help lower swr?

Hmm, could be a couple things, first would be to check that the amp is hooked up right. Next check both jumpers without the amp inline. Last is the Grant's output is too low to get a proper reading going through the amp.

3's

Greg

[Bluerunner]

Is your SWR meter before or after the amp?

If it is after the amp, are you re calibrating the SWR meter with the amp on?

[cecil]

Is your SWR meter before or after the amp?

If it is after the amp, are you re calibrating the SWR meter with the amp on?

SWR meter is after amp. Calibrating with amp on.
Hooked up this way: radio to amp to meter to antenna.

[KOA4705]

Ok, so I am experiencing some high swr readings with the amp in place. Here is what I have for a base setup:
Grant LT dead key 1w, swings 12 or so.
RM Italy 203P, new
Max 2000 antenna, new this year.
RG213 coax, new this year.
(2) 3' RG8x jumpers, checked continuity, ok.
Dosy meter, works fine as I know it.
With setup without amp, I get swr of 1.1 on Chan. 1 and 1.05 on Chan. 40
With amp in place, I get swr of 2.3 on Chan. 1 and 1.7 on Chan. 40
I checked this twice, maybe more. All connections are tight. I have got good reports on the Grant without the amp, so wondering what is going on here. I do not have a antenna analyser. Hesitant to use amp with reading this high.
Would a low pass filter inline with amp to meter help lower swr?

Cecil your radio output is looking into two different loads. Without the amp the output of the radio is looking into the impedance of your antenna system. With the amplifier on the radio is looking into the input impedance of the amplifier. So the swr will change unless both impedances are identical. What is the output power on channel 20 with the amp on ?

[KOA4705]

Ok, so I am experiencing some high swr readings with the amp in place. Here is what I have for a base setup:
Grant LT dead key 1w, swings 12 or so.
RM Italy 203P, new
Max 2000 antenna, new this year.
RG213 coax, new this year.
(2) 3' RG8x jumpers, checked continuity, ok.
Dosy meter, works fine as I know it.
With setup without amp, I get swr of 1.1 on Chan. 1 and 1.05 on Chan. 40
With amp in place, I get swr of 2.3 on Chan. 1 and 1.7 on Chan. 40
I checked this twice, maybe more. All connections are tight. I have got good reports on the Grant without the amp, so wondering what is going on here. I do not have a antenna analyser. Hesitant to use amp with reading this high.
Would a low pass filter inline with amp to meter help lower swr?

Cecil your radio output is looking into two different loads. Without the amp the output of the radio is looking into the impedance of your antenna system. With the amplifier on the radio is looking into the input impedance of the amplifier. So the swr will change unless the reflection coefficient(P) is identical. The swr meter needs to be at the output of the radio for this measurement. What is the output power with the amp on ?

swr.jpg

[cecil]

Ok, so I am experiencing some high swr readings with the amp in place. Here is what I have for a base setup:
Grant LT dead key 1w, swings 12 or so.
RM Italy 203P, new
Max 2000 antenna, new this year.
RG213 coax, new this year.
(2) 3' RG8x jumpers, checked continuity, ok.
Dosy meter, works fine as I know it.
With setup without amp, I get swr of 1.1 on Chan. 1 and 1.05 on Chan. 40
With amp in place, I get swr of 2.3 on Chan. 1 and 1.7 on Chan. 40
I checked this twice, maybe more. All connections are tight. I have got good reports on the Grant without the amp, so wondering what is going on here. I do not have a antenna analyser. Hesitant to use amp with reading this high.
Would a low pass filter inline with amp to meter help lower swr?

Cecil your radio output is looking into two different loads. Without the amp the output of the radio is looking into the impedance of your antenna system. With the amplifier on the radio is looking into the input impedance of the amplifier. So the swr will change unless both impedances are identical. What is the output power on channel 20 with the amp on ?

The output power on ch. 20 with amp on roughly 20w dead key to 180w when modulating. This is where the power rating makes sense to me, as the PEP is listed at 200w. Still my swr is too high here.
On channel 1: 15w dead to 125w
On channel 40 38w dead to 240w.
Please note:
I reversed the swr readings by mistake on the original post.
Amp on:
ch. 1 1.7
Ch. 20 1.9
ch. 40 2.3

Now my head is spinning!

[MDYoungblood]

The wattage level you are stating is making me think the meter is the problem, on a good day in a perfect world, a 203P is not going to yield that output. I'd take those exaggerated manufacturer wattage claims with a grain of salt. I would stop with trying to get the amp right and work on getting the SWR better or you'll be buying another amp soon.

3's

Greg

[cecil]

The wattage level you are stating is making me think the meter is the problem, on a good day in a perfect world, a 203P is not going to yield that output. I'd take those exaggerated manufacturer wattage claims with a grain of salt. I would stop with trying to get the amp right and work on getting the SWR better or you'll be buying another amp soon.

3's

Greg

How do I get the swr down? Without the amp in place, I’m 1.1. This is true for both my radios. Add this little box of hell and it throws a wrench in.
I’m going to go off the meter in the radio for a swr check, I haven’t done that yet. Disconnecting the Dosy meter and we’ll see. Roll the dice!

[cecil]

Well, I might have fixed the issue. I received a low pass filter (27/586) in the mail today. I put it inline between the amp and the Dosy meter. Here is what I got:
Ch. 1 swr is 1.3 and 10w dead to almost 100w.
Ch. 40 swr is 1.32 and 12w dead to 100w.
SSB is close to 110 PEP.
I can definitely live with these numbers.
Maybe I have some secondary harmonics or RF interference here. Computer, printer, wifi, etc.
Hopefully this problem is solved.
Appreciate all the help from everyone!

[KOA4705]

Ok, so I am experiencing some high swr readings with the amp in place. Here is what I have for a base setup:
Grant LT dead key 1w, swings 12 or so.
RM Italy 203P, new
Max 2000 antenna, new this year.
RG213 coax, new this year.
(2) 3' RG8x jumpers, checked continuity, ok.
Dosy meter, works fine as I know it.
With setup without amp, I get swr of 1.1 on Chan. 1 and 1.05 on Chan. 40
With amp in place, I get swr of 2.3 on Chan. 1 and 1.7 on Chan. 40
I checked this twice, maybe more. All connections are tight. I have got good reports on the Grant without the amp, so wondering what is going on here. I do not have a antenna analyser. Hesitant to use amp with reading this high.
Would a low pass filter inline with amp to meter help lower swr?

Cecil your radio output is looking into two different loads. Without the amp the output of the radio is looking into the impedance of your antenna system. With the amplifier on the radio is looking into the input impedance of the amplifier. So the swr will change unless both impedances are identical. What is the output power on channel 20 with the amp on ?

The output power on ch. 20 with amp on roughly 20w dead key to 180w when modulating. This is where the power rating makes sense to me, as the PEP is listed at 200w. Still my swr is too high here.
On channel 1: 15w dead to 125w
On channel 40 38w dead to 240w.
Please note:
I reversed the swr readings by mistake on the original post.
Amp on:
ch. 1 1.7
Ch. 20 1.9
ch. 40 2.3

Now my head is spinning!

Cecil when the amplifier is disabled the transmitter output go directly to
the antenna system via a relay in the amplifier. If the amplifier is enabled the relay is energize the transmitter output is redirected to the input of the amplifier. Also in this state the relay connects the output of the amplifier to your antenna system. My conclusion is swr issue is due to the input impedance of your amplifier. Even with a worse case swr of 2.3 : 1, 84.5-% of your transmitter power is being delivered to the input of the amplifier. What is the amplifier operation frequency range specified by the manufacturer?

[KOA4705]

Is your SWR meter before or after the amp?

If it is after the amp, are you re calibrating the SWR meter with the amp on?

SWR meter is after amp. Calibrating with amp on.
Hooked up this way: radio to amp to meter to antenna.

So what your saying the swr meter is on the output of the amplifier?

[cecil]

Is your SWR meter before or after the amp?

If it is after the amp, are you re calibrating the SWR meter with the amp on?

SWR meter is after amp. Calibrating with amp on.
Hooked up this way: radio to amp to meter to antenna.

So what your saying the swr meter is on the output of the amplifier?

Yes, that is correct. The RM Italy 203p is for use on 11 meter. Now that I have the low pass filter inline between the amp and meter, my swr has dropped to 1.3 or less across channels 1-40. It’s working ok. A 1 to 1 match would be great, but I can live with what I’ve got. Thanks

[KOA4705]

Is your SWR meter before or after the amp?

If it is after the amp, are you re calibrating the SWR meter with the amp on?

SWR meter is after amp. Calibrating with amp on.
Hooked up this way: radio to amp to meter to antenna.

So what your saying the swr meter is on the output of the amplifier?

Yes, that is correct. The RM Italy 203p is for use on 11 meter. Now that I have the low pass filter inline between the amp and meter, my swr has dropped to 1.3 or less across channels 1-40. It’s working ok. A 1 to 1 match would be great, but I can live with what I’ve got. Thanks

Cecil congratulations Impressive! How did you evaluate this problem to realize the cause was the amplifier output harmonic content?

[MDYoungblood]

Just out of curiosity I would remove the filter and place a barrel connector there instead just to see if the added length of coax helped the problem.

3's

Greg

[cecil]

Is your SWR meter before or after the amp?

If it is after the amp, are you re calibrating the SWR meter with the amp on?

SWR meter is after amp. Calibrating with amp on.
Hooked up this way: radio to amp to meter to antenna.

So what your saying the swr meter is on the output of the amplifier?

Yes, that is correct. The RM Italy 203p is for use on 11 meter. Now that I have the low pass filter inline between the amp and meter, my swr has dropped to 1.3 or less across channels 1-40. It’s working ok. A 1 to 1 match would be great, but I can live with what I’ve got. Thanks

Cecil congratulations Impressive! How did you evaluate this problem to realize the cause was the amplifier output harmonic content?

Just by luck! I researched others having this problem and decided to purchase a low pass filter. I have 3' jumpers in between.

[cecil]

Just out of curiosity I would remove the filter and place a barrel connector there instead just to see if the added length of coax helped the problem.

3's

Greg

Ill have to pick up a barrel connector and try...probably a elbow type as its a tight fit. I would also like to try a 1' jumper in lieu of the 3' one. Still learning! Thanks Greg

[KOA4705]

Is your SWR meter before or after the amp?

If it is after the amp, are you re calibrating the SWR meter with the amp on?

SWR meter is after amp. Calibrating with amp on.
Hooked up this way: radio to amp to meter to antenna.

So what your saying the swr meter is on the output of the amplifier?

Yes, that is correct. The RM Italy 203p is for use on 11 meter. Now that I have the low pass filter inline between the amp and meter, my swr has dropped to 1.3 or less across channels 1-40. It’s working ok. A 1 to 1 match would be great, but I can live with what I’ve got. Thanks

Cecil congratulations Impressive! How did you evaluate this problem to realize the cause was the amplifier output harmonic content?

Just by luck! I researched others having this problem and decided to purchase a low pass filter. I have 3' jumpers in between.

No not luck you did the research to resolve the problem. Others will benefit from this post.

[KOA4705]

Just out of curiosity I would remove the filter and place a barrel connector there instead just to see if the added length of coax helped the problem.

3's

Greg

What is the purpose of adding or reducing coax length?

Ill have to pick up a barrel connector and try...probably a elbow type as its a tight fit. I would also like to try a 1' jumper in lieu of the 3' one. Still learning! Thanks Greg