LOW PASS FILTER

[Plumber-G]

To test a filter you need a signal generator to put a signal thru it and preferably an oscilloscope to look at the output to see how far down the signal is.

Captain, I assume to test a filter I would induce a signal from the signal generator to the input of the filter and connect the output to a dummy load with a sampler to the oscilloscope ?? then increase / decrease the frequency to see were the filter stops output??
Is a dummy load necessary with a signal generator??

 

[Captain Kilowatt]

Captain, I assume to test a filter I would induce a signal from the signal generator to the input of the filter and connect the output to a dummy load with a sampler to the oscilloscope ?? then increase / decrease the frequency to see were the filter stops output??
Is a dummy load necessary with a signal generator??

The load is not necessary to determine if the load is good to use safely with a TX but it will help determine the actual attenuation since it is designed for a 50 ohm system.

 

[Plumber-G]

I tested the one I have and it started diminish the signal at 33 mhz and completely stopped it at 38 mhz on the low end it never diminished or stopped.
I know I am not using the proper terminology but I think you get the idea<GRIN>

Fun Experiment tonight...... Beats watching TV

 

[Road Squawker]

Well, you could get a cardboard tube and stuff it full of steel wool, and....

 

[OldTech03]

The following 3 images are of the BUD filter I redid this morning


Here is a quick rundown on some of the filters I have laying around. I read this post at 3: AM this morning because I was not able to sleep and ended up restoring an old BUD 601 and then decided to test all of the filters I have laying around on the Spectrum Analyzer. So below are the results of all three. The Blue one which is a CHANNEL GUARD XL-1000 was very touchy to get aligned but that could speak to cheaper construction and parts the BUD was very smooth and easy to tune after it was serviced and the DF4000 is one speed so what it is is what it is.

The DF4000 did have a lower cutoff frequency around 30.5 Mhz while the Bud was around 39 Mhz and the Channel Guard was right at 31.5 Mhz. They showed a pretty flat response -79 go -82 dBm from around 45mhz right up to 100Mhz

So this may shed some light on subject hope you enjoy now I must get back to work.

Please feel free to correct any errors as it was a long morning and I didn't bother to check my spelling LOL..

 

[Tallman]

The following 3 images are of the BUD filter I redid this morning

Now that's a test bench any body could be proud of!

 

[Low_Boy]

Nice job VT

 

[Eldorado828]

Reviving an old thread



So as to the df3000, any of you fellas use one of them before? There's a few for sale on the fleebay and wondered if they're a decent lpf.

 

[Shadetree Mechanic]

Reviving an old thread

View attachment 62111

So as to the df3000, any of you fellas use one of them before? There's a few for sale on the fleebay and wondered if they're a decent lpf.

I run one in my shack, seems to work ok. Although I have no real way to measure it's performance.

 

[Eldorado828]

I run one in my shack, seems to work ok. Although I have no real way to measure it's performance.

With it getting rough and tough going into this cycle, I'm thinking a 503hd behind either the original 5555N or one of my other lower power radios. The radio's are all clean but sure don't want any problems with neighbors and the reason asking about the df3000.