Uniden 980 SSB Watts Lower on Higher Channels?

[CenTex519]

I have the Uniden Bearcat 980 and have been talking on the sideband. I have tuned my antenna and get an SWR of 1.75 on both AM 1 and 40. I'm dialed in to an SWR of almost a perfect 1 on AM 20. I can hit 4 watts on all AM frequencies. I have done nothing to the radio.

I got into hanging around 38 LSB and decided to check the power output across the Sideband. I peg at a strong 12 watts on channels 1-30 but loose output on 31-40. It's only holding 2-4 watts while audio checking and swinging to maybe 8 when I initially key up and audio check.

Does anyone have any experience or insight that could help me get better output in the high channels? I'm not looking to do a hack job on the radio, I just want it to give me my legal output on SSB.

Thanks!

 

[kc4jgc]

Keep in mind that sideband emission is 100% modulation driven. When you key up with little or no audio there will be little PEP. Maximum audio will produce maximum PEP.

As far as your output on SSB, I too find it odd that your unable to transmit 12w PEP if you can transmit 4w AM. May be a an issue specific the the SSB transmitter.

 

[prcguy]

I would always use a 50 ohm dummy load because even though your antenna shows a good match it can make the internal meter read wrong. I would also check the power with a known accurate external meter and load and you will probably find the power is just fine across the band.
prcguy

 

[CenTex519]

Thanks

Thank you for the input so far. I should mention that I have been using the Astatic external PDC1 meter to check SWR and Wattage.

I have a K-30 magnetic base antenna.

 

[Retroradio]

Stock or power mic?

 

[CenTex519]

Power Mic. Astatic Road Devil RD104E

 

[SCPD]

You can't measure power correctly with an antenna. You need a 50 ohm dummy load and a decent VSWR meter. The meter you have now is not very good. I would venture to say if you place it on a dummy load it will read the same power across the 40 channels. JMO. Also how are you checking the output on SSB? Hopefully with a 1000hz sine wave tone. Your phone should have an app for this. But like I said, using the antenna to perform this won't work correctly. And also a 1.75:1 VSWR is going to end up blowing that final at some point. The finals used in most if not all CB radios are not true RF type Mosfets. They can be made to work, but aren't truly made for that purpose. Now an HF or ham radio does use RF type Mosfets for the PA. And the K30 is a POS antenna. Sorry not trying to be rude, but a 3ft antenna is about like placing a coat hanger on a magnet mount. The bandwidth is very narrow and they usually don't tune very well. Just my experience with these type of antennas. Get an antenna that is at least 6ft or longer. You'll notice a big difference in your RX and TX distance and most likely a better match or VSWR reading. Remember that all these antennas will tune to only 1 frequency at resonance. You might see a good VSWR on channels 1 and 20, but there is more to antennas and how they work then just VSWR.
prcguy is totally correct with what he stated as well. Get rid of the truck stop VSWR (SWR) meter and find a better one. Diawa makes a good meter, or even find a radio shack meter off eBay or check around at your local radio shack, some still carry the VSWR/watt meters.
Do some research on how mono band antennas work. Also the connector that is on the end of that mag mount you have is a problem area as well. If it's the 2 piece sma to PL259 adapter. They are a known failure point. But IMO, with the VSWR as high as it is (1.75:1), your radio isn't going to last very long. Those finals are already a known weak point and don't like VSWR above 1.3:1. They create a lot of heat and will show you readings just like what you are seeing. Again, these are just my experiences with antennas using an antenna analyzer. Like I said, read up some about your antenna (k30 magnet mount), and you'll find that what you are experiencing is quite normal for these type antennas. Hope this helps and don't get discouraged. It's not your radio. JMHO's. And again, hope this helps. Have a good day sir.

 

[SCPD]

Also read up on what reactance, resistance, impedance and VSWR, not SWR, all mean and how they affect things.

 

[prcguy]

At one time I worked for the largest CB mfr in the world and had my hands inside more CBs than most people. I can tell you the final RF transistors in any CB made since the early 1970s through today are purpose designed and made for CB service. They may be found in a few other radios but they were all made with CB in mind because its the largest customer for the product. Mosfets are relatively new to the CB market with plain old bipolar devices being the most prevalent.

I've also tried to destroy countless CBs over the years by disconnecting the antenna and transmitting for long periods of time. I was never able to hurt one and that includes the cheapest bottom of the line and some high end radios. Even today I will take any of the CBs laying around here and will transmit with no antenna all day long to make a point and I'm confident nothing bad will happen to it. With that said I don't think a 1.75:1 VSWR will hurt any radio.
prcguy

You can't measure power correctly with an antenna. You need a 50 ohm dummy load and a decent VSWR meter. The meter you have now is not very good. I would venture to say if you place it on a dummy load it will read the same power across the 40 channels. JMO. Also how are you checking the output on SSB? Hopefully with a 1000hz sine wave tone. Your phone should have an app for this. But like I said, using the antenna to perform this won't work correctly. And also a 1.75:1 VSWR is going to end up blowing that final at some point. The finals used in most if not all CB radios are not true RF type Mosfets. They can be made to work, but aren't truly made for that purpose. Now an HF or ham radio does use RF type Mosfets for the PA. And the K30 is a POS antenna. Sorry not trying to be rude, but a 3ft antenna is about like placing a coat hanger on a magnet mount. The bandwidth is very narrow and they usually don't tune very well. Just my experience with these type of antennas. Get an antenna that is at least 6ft or longer. You'll notice a big difference in your RX and TX distance and most likely a better match or VSWR reading. Remember that all these antennas will tune to only 1 frequency at resonance. You might see a good VSWR on channels 1 and 20, but there is more to antennas and how they work then just VSWR.
prcguy is totally correct with what he stated as well. Get rid of the truck stop VSWR (SWR) meter and find a better one. Diawa makes a good meter, or even find a radio shack meter off eBay or check around at your local radio shack, some still carry the VSWR/watt meters.
Do some research on how mono band antennas work. Also the connector that is on the end of that mag mount you have is a problem area as well. If it's the 2 piece sma to PL259 adapter. They are a known failure point. But IMO, with the VSWR as high as it is (1.75:1), your radio isn't going to last very long. Those finals are already a known weak point and don't like VSWR above 1.3:1. They create a lot of heat and will show you readings just like what you are seeing. Again, these are just my experiences with antennas using an antenna analyzer. Like I said, read up some about your antenna (k30 magnet mount), and you'll find that what you are experiencing is quite normal for these type antennas. Hope this helps and don't get discouraged. It's not your radio. JMHO's. And again, hope this helps. Have a good day sir.

 

[CenTex519]

A Big Thanks

Thank you everyone for the great input. It's awesome that you all took the time to get me moving in the right direction.

 

[SCPD]

Yes I understand bipolar transistors, but the devices being used in today's radios, which are Mosfets not made for RF will indeed take a crap with a bad match or VSWR. I've been there and done that.
Read this and maybe it will clear things up.

And I am not a CB tech. Just one that has had experience with these type devices. And VSWR does matter.
We are speaking of CB RADIOS and not HF RADIOS here so let's not forget this. Don't want to argue, so I won't post anymore about the subject. But read the article please before you go flaming me!!!