ProStick + , external amp + filter combination?

Hi all, proud owner of a ProStick+, astounding performance over my other equipment, I am well satisfied.
However, I was wondering if it would be worth installing an Uptronics Amp/filter Combo, along with a FA filter inline with the antenna. The antenna is an 8 ele CoCo that also performs quite well.

I don’t want to overload the front end of the ProStick+ but would like to know if it would make any difference or is the PS+ good enough.



How are you doing in comparison to your ‘neighbors’? There is a point where more equipment won’t do anything worthwhile.

No need for so many filters. I think you can ‘drop’ the FA one.

Adding an amp may be a good thing, but may also cause overload. The PS+ has a built-in amp. Be prepared to tweak the PS+ gain, very likely lower.

Amps will not discriminate between signal and noise. It’s an equal opportunity device.

Back to the beginning. If you are doing OK compared to others in your area, move slowly.

He said he’s using the FA blue stick with a FA filter and a CoCo.

The CoCo probably filters better on it’s own than the FA filter. I’m sure he tested without it?

One of the saw filters for 16 pounds sounds like it would be worth a try.
If you go for an amp you will need to supply it with power. And because you can overload the amp in teh FA blue stick going with an rtl-sdr dongle combined with an amp might work better.
But the amp filter combo in the FA blue stick is already quite good.

Anyway all those people with working Cocos what’s going at the moment? :slight_smile:

Did you build the Coco yourself and if yes according to which specs / which cable?

I thought he was thinking of adding the Uptronics and the FA filter to the PS+ and CoCo.

That has a filter and preamp inside.

It’s pretty good as is, I have a preamp with filtering in front of it but truthfully… didn’t do that much good, I had to lower the gain on the receiver. Maybe if I had a longer cable and install the amp at the antenna…

I am also interested to know these details, though after making a dozen or so cocos, ALL failed, I have come to conclusion that DIY Coco is a dark art. Only few lucky ones endup with a good coco.

I think that the velocity correction factors might have been applied wrongly :wink:

The “active” part of the antenna elements is actually the outside shield. The shield is covered in PVC, that has a different coefficient than the core insulator.
I don’t know the velocity for PVC, I think is pretty high, around 0.9. However the PVC should be tested in microwave oven - it should remain cold after 30 seconds of microwaving.

Core foam-teflon is 0.82, polyethelene is 0.66. So those segments (transmission trough internal core) should be corrected differently, for that core material.

Starting from top is: antenna (outside shield), delay line, antenna, delay line…

“The VF for most common insulating materials is between 0.95 – 0.98 (PVC, Polyethylene, Teflon) so be sure to take that into account as well.”

Another page says:

“I see some engineering textbooks use 0.99 or 0.98 for various popular materials like polyethylene, PVC and Teflon.”

I knew is high, but not sure how high. However some might have metallic paint in the mix, and the PVC tubes the same. Those should be avoided and that’s why the microwave test.

The core material is given in specification of that cable, if is from a serious manufacturer.

It’s about the constructive interference of radio waves so the different antennas in one run in sync. Therefore it is indeed the Vf of the coax which is of interest.

True the antennas on each own are not perfect but the phase alignment is the critical thing.

@abcd567 did you try different measurements for the same coax cable?

115 and 117 mm for example?

also abcd567 if you feel like trying something try my dump fork :wink: (just for contributing to upstream)
(adjustable history size/interval so when you call up the page the tracks are not as edgy. also has nicer track changes as in less edges. still should be much quicker cpu wise if you care.)

Has anyone used this one?

Seems to be good for use with a GENERIC DVB-T

In from Antenna >> LNA1 >> SAW Filter1 >> LNA2 >> SAW Filter2 >> Out to receiver

$17.73 + Free Shipping from China

ADS-B 1090MHz RF low noise Amplifier 38dB

  1. working voltage: 3.3 - 5.0V (DC)

  2. working frequency: 1090MHz (ADS-B receiving special)

  3. amplification gain: 38dB

  4. out of band inhibition: -75dB@±50MHz; -55dB@±1GHz

  5. special design: double filter structure is adopted to ensure enough suppression of out of band signal and effectively improve the signal to noise ratio.


Why does it matter?

The element length is calculated by the wavelength/2 times the Vf because it must be a half wavelength transmission line. The outer sheath does not come into it and the actual length of the antenna elements is determined only by the Vf of the transmission line coax and the frequency.

If the Vf is lower the “active part of the antenna” as you put it will be shorter. The PVC does not change this.

If the Vf is higher the radiating or active part will be longer and therefore closer to a half wavelength which is a good thing.

The reference to a SLEEVE BALUN implies there is a balanced feed somewhere. Could someone please point out where?


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Yes, I built it myself. Originally I had one on the ground at about 10 feet high, without the shorted top, but the building shielded it from the East, so I quickly built another, with a shorted top, mounted it on the chimney stack.

It works pretty well, still not sure whether i should have done the un-shorted design up there, I May put the other one next to it and compare one day.

I built them out of RG58U and mounted them in an old ScanStick Wideband Antenna Shell, it was a rubbish performer so I sacrificed it

I didn’t use a sleeve balun at all, on the diagrams i used there wasn’t one.

I was thinking of it, that’s why I asked if it would overload/be of any use. I am on par with neighbouring sites but, as I have them lying around here I thought i’d put them to use.

So try it out. If you don’t want to overload the stick just put the FA filter between the stick and the amp that’s some attenuation at least :stuck_out_tongue:
Not sure about supplying power though, is the amp fed directly?

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Yes, it’s the Uptronics one with the USB on the side,

This is the antenna that worked at 10 feet , 1/4wave bottom and 1/4wave top, shorted, and a 1/4 whip added.

Mounted in square section conduit.

The rtl-sdr amp has a gain of 27dB as it is double stage. So having the two stages in two different devices should not be a problem. The FA filter won’t do much after the signal has passed the uptronics amp you might still put it in front of it to reduce strong intereference which the LNA might not like.

The uptronics is listed at 16 dB of gain not sure what gain the blue FA dongle has.

Anyway just reduce the gain in software another 15 dB, what is the typical dbFS number your skyview shows for planes 15 miles away?

It could well be that the LNA in the uptronics is better quality and/or better shielded so using it could improve the noise ratio slightly.

And i’m still curious what element length did you use. And do you mean literally shorted at the end or did you put a 50Ohm resistor across it?


Not too bad all round coverage.