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preamp not working right

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cdj85
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preamp not working right

#410283

Post by cdj85 »

I have a 203p that seemed to be working fine. Then one day when I flipped it on, it would not work. I put the radio, amp, filter in a different truck and it works fine. I have a low pass filter between the amp and antenna. I tried a different antenna and did the same thing. When I have the antenna disconnected and the preamp on, the needle increases until I screw down the antenna, then it goes away or screeches. I plugged the antenna directly into the amp bypassing the filter and it works like it should. I had another new filter and put that in and it does the same thing. I'm not sure what the problem is. Maybe the cable between filter and amp, but it works fine in the other truck. Any thoughts to this problem?

Another question, what mount would work for a 5 ft firestik if I wanted to mount it on the roof? I still haven't got a backrack setup yet.
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#410284

Post by 295 antenna »

Silly question but is your radio and antenna grounded
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cdj85
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#410285

Post by cdj85 »

Yes they are, at least normally the radio is. But since you mentioned that, now I'm not so sure I secured the radio ground back up when I transferred the radio. I'll have to look at that. Thank you.


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Added 14 hours 3 minutes 32 seconds after previous.
It is grounded and does the same thing. When it does bump up the signal, it comes in almost screeching or howling. If I turn the volume up loud it goes down a tad. Other times when I have flipped the switch on the signal has gone down. But only in the 1 vehicle.
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#410298

Post by MDYoungblood »

That is a new one on me, most questions about pre-amp’s deal with increased noise level. You said it worked fine in another vehicle so it is probably an antenna problem. Check to make sure the coax where it entered the vehicle isn’t crushed, kinked, or just bad.
As far as a mount goes, look at a tri-magnet, 3/8-24 thread. Ut will work with any antenna after you decide on a headache rack.

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cdj85
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#410304

Post by cdj85 »

Those racks are expensive. Now I'm thinking of putting it on the roof. The preamp works as I believe it should when I bypass the low pass filter.
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#410308

Post by Bozo »

It sounds like the low pass filter is the problem. When you connect the antenna directly to the amp, the signal is not being filtered and is able to pass through to the amp.

However, when you connect the antenna through the filter, the filter is blocking the signal and preventing it from reaching the amp. This is why you are only getting a screeching noise when you have the antenna connected to the filter.

There are a few different things you can try to fix this problem.

First, you can try a different low pass filter. If you have another filter that you can try, it would be worth a shot to see if that one works. If you don't have another filter, you can try contacting the manufacturer of the filter that you are using to see if they have any suggestions.

Another thing you can try is to adjust the settings on the filter. Some filters have adjustable settings that can be used to fine-tune the filter's performance. If your filter has adjustable settings, try adjusting them until you get the best signal.

If you have tried all of these things and you are still having problems, then the filter may be defective. In this case, you will need to contact the manufacturer of the filter to request a replacement.

As for your second question, there are a few different mounts that you can use to mount a 5 foot Firestik antenna on the roof of your truck. One option is to use a roof-mount antenna base. These bases are designed to mount antennas on the roof of vehicles. They come in a variety of sizes and styles, so you should be able to find one that will fit your vehicle.
EZ-17.jpg
Another option is to use a magnetic mount antenna. These mounts use a strong magnet to attach the antenna to the roof of your vehicle. They are a quick and easy way to mount an antenna, but they are not as secure as a roof-mount antenna base.

No matter which type of mount you choose, make sure that you follow the instructions carefully to ensure that the antenna is mounted securely



A puck antenna mount is a type of antenna mount that uses a metal base to attach the antenna to the vehicle. This type of mount is more secure than a magnet mount, which uses a magnet to attach the antenna to the vehicle. Puck antenna mounts are also more durable than magnet mounts, and they can withstand more wear and tear.

Here are some of the reasons why a puck antenna mount would be better than a magnet mount:

*
Puck antenna mounts are more secure.
A puck antenna mount uses a metal base to attach the antenna to the vehicle. This type of mount is more secure than a magnet mount, which uses a magnet to attach the antenna to the vehicle. A magnet mount can easily come loose, especially in windy conditions.
* Puck antenna mounts are more durable.
Puck antenna mounts are made from durable materials, such as stainless steel. This type of mount can withstand more wear and tear than a magnet mount, which is made from a softer material.
* Puck antenna mounts are easier to install.
Puck antenna mounts are easier to install than magnet mounts. A puck antenna mount can be installed with a few simple tools. A magnet mount requires more time and effort to install, and it can be more difficult to get a good seal.

If you are looking for a secure, durable, and easy-to-install antenna mount, then a puck antenna mount is the best option for you.

Here are some additional things to consider when choosing an antenna mount:

* The type of vehicle you have.
Some puck antenna mounts are designed for specific types of vehicles, such as trucks or SUVs. Make sure to choose a mount that is compatible with your vehicle.
* The size of the antenna.
Some puck antenna mounts are designed for specific sizes of antennas. Make sure to choose a mount that is the right size for your antenna.
* The price.
Puck antenna mounts can range in price from a few dollars to several hundred dollars. Choose a mount that fits your budget.
DaveMade_puck_with_plate-2167134 (1).jpg
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cdj85
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#410315

Post by cdj85 »

Thank you for the reply. I have 2 of the same filter and had the same results. It isn't tunable so that isn't an option. I thought it was the filter as well but it does not do it when connected to a different vehicle. I am waiting on a breedlove puck to show up to move the antenna to the roof and I'll see what that does.
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#410339

Post by MDYoungblood »

I would lose the filters, they are a thing of the past since television has gone digital and the broadcast frequencies have changed, plus in a mobile application they aren’t needed anyway.

3’s

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cdj85
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#410347

Post by cdj85 »

I changed out the 4' and put the 5' antenna on. It seemed to work better then. That was on a mount between the fender/hood. I got the breedlove mount in the mail and put it on yesterday. It's working as it should now. Don't think anything was wrong with the filter/amp
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#410348

Post by Deleted User 30222 »

MDYoungblood wrote: Jun 09 2023, 07:34 I would lose the filters, they are a thing of the past since television has gone digital and the broadcast frequencies have changed, plus in a mobile application they aren’t needed anyway.

3’s

Greg
Thanks blood, was wondering about that myself with the new setup. Didn't want to upset the neighbors. But didn't even think of about that aspect.
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cdj85
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#410349

Post by cdj85 »

Another thing I noticed is I cannot get the swr low enough for my liking. The 5' firestik I was able to get to 1.1:1 which was good. I had 16 watts out and about 0.1 reflected (power tested in different location).
The wilson 2000 I can only get to 1.55:1 I had 10 watts out and .7 watts reflected (power was tested in a different location).

I was hoping to run the 2000 as I noticed a little vibration on the roof with the firestik but I'm not sure I want that much reflection with an amp.


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Added 1 minute 29 seconds after previous.
I wonder if I use a 22" shaft instead of the 10" if that would be better.
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