Preselector and/or tuner?

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majoco

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IMHO a "tuner" is connected at the end of a longwire antenna and changes the impedance of the antenna to the input impedance of the radio - the only bit of coax is that between the tuner and the radio. Some radios had a built in tuner - sometimes called "Ant Tune" and sometimes called "Preselector" - FRG7 for instance - but the longwire end must go directly to the radio which leaves it open to interference generated from inside your house. You can't use coax as it just looks like a capacitor and shunts some of the signal to ground.
Now that you have fitted a (probably 9:1) transformer up at the end of the longwire and bought the coax down to the receiver, your "tuner" has become a "preselector" - it will pick out (but not enhance) the signal you want and reject the others. It can't change the input impedance as you have already changed that up at the transformer.
I do exactly that, except my transformer is a home built 9:1 from the John Bryant articles (Google for "A Second Look at Fabricating Impedance Transformers for Receiving Antennas") and a Yaesu FRT-7700 "tuner" at the radio. Works well at rejecting unwanted BC band signals but does nothing to improve the signal strength - the "S" meter doesn't move when switched in or out.
But anyway, give it a try and experiment - that's half the fun!
 

SCPD

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I currently have wire anttna up using a WiNRADiO Long Wire Adapter and am unsure if i should add a preselector and/or tuner to my setup? Oh and the reciever I'm using is a satellit 750.
Honestly, with that kind of receiver, it's not worth the extra cost.

Eventually, if you decided to invest in a higher-grade receiver then it might make more sense. A lot of newer receivers (and SDRs) do not need this extra option. A medium to high-end SDR usually provides this extra hardware built-in. Most true "HF Receivers" already have a "high-pass filter" built in. This is not a pre-selector but it's good enough since the receiver circuitry is usually good enough to not need it.

The Longwire adapter you have is an un-un -- which is similar to a balun -- but it's unbalanced to unbalanced. In this case, the wire end is just a random wire. The un-un probably uses a 9:1 ratio but it may be something custom.

This combination is fine for what you have now.

You didn't say if you live in the city or in a rural location. The biggest question is noise. How much RFI do you put up with, etc. If you're overall noise is low then you probably won't need to change anything.

If you are in the city and are hearing a bunch of buzzing or repeating signals (that seem to show up every few khz) then you likely need to solve your noise problems.

Depending on your noise level, your antenna is probably OK. If you are in a quiet location, then you may want to invest in an alternate antenna. A amplified loop is a good choice. They are not cheap so there's an initial investment involved but it can really change your listening experience.

Again, it just depends on how serious you are about the hobby and how much money you're willing to spend.

Since you asked, here's a cheap option if you're willing to spend the extra cash. The only downside is that you'll need a couple of custom coax cables or use adapters to convert the BNC to PL259.

This is a pretty simple device to use and fairly straight-forward.

http://universal-radio.com/catalog/preamps/2964.html
 

ka3jjz

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Let's clarify a couple of things here.

There are really 2 different types of 'preselectors' - passive and active. Passive preselectors are good for creating a 'gate' that will help eliminate out of band signals without adding additional amplification. McKay Dymek (a company that i think is long gone) used to sell these, and if memory serves, MFJ also has one of these.

An active preselector adds additional gain in addition to creating a 'gate'. Palomar sells one, I think (I have one in storage...) and it works well. However these take some practice to use properlty. Most people when they start off think that louder is better - however they don't realize that they are often adding noise, as well as signal. One needs to learn how to add just enough amplification without increasing the noise - and that takes practice, as that level can and often does vary from band to band.

I agree with the other posters who say that you probably don't need either a preselector (regardless of type) or tuner. Improve your antenna - you won't hurt your wallet nearly as much. There are numerous designs linked in our wiki, and a simple Google search will undoubtedly turn up many more. Don't shy away from 'amateur radio' designs, either - with the application of a little math, many will work just fine for SWBC and utility listening. I wouldn't make the antenna too long, though. You may end up with overloading - if you start hearing stations where they don't belong, this is one possible cause. Many of the top DXers use more than one antenna, and switch between them. Propagation can be fickle - what doesn't come in well on one antenna may come in just fine on another of a different type. We discuss such antennas here

Mike
 
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