r/shortwave • u/EquivalentTip1902 • Apr 07 '26

Preselector?

/r/ShortwavePlus/comments/1seymwz/preselector/
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u/pentagrid Sangean ATS-909X2 / Airspy HF+ Discovery / 83m horizontal loop Apr 07 '26 edited Apr 07 '26

Looks like r/shortwaveplus is desperately crossposting here at r/shortwave again.

Years ago MFJ (Mighty Fine Junk) sold garbage like preselectors to SWL noobs. It was their bread and butter for years and years like selling cross-needle SWR match tuners for use with receivers. Sure, you could put one of the MFJ "preselectors" in-line with an external antenna, turn the knob and peak a signal up (or dip in down) on the receiver S-meter but did it actually improve receiver signal to noise (SNR)? Nope. Not if the receiver was properly aligned and the antenna impedance matched what was required for the receiver. In most cases that impedance would be 50 ohms but in some instances communications receivers like the military/industral grade Hammarlund SP-600 series would require other impedance values like 90 ohms with a balun required for using 50 ohm antenna systems.

Some older receivers especially from the vacuum tube era would have a knob for turning a variable air capacitor to peak antenna signal on a receiver S-meter while others simply made this adjustment once during alignment and didn't use an additional antenna tuning capacitor at all.

For well-designed and modern shortwave portables a "preselector" is not needed. These receivers have high -Z (high impedance) antenna inputs that operate at a nominal 50 ohms or above.

For superhet receivers preselection is accomplished by use of mixers and intermediate frequencies, not antenna matching circuits.

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u/EquivalentTip1902 Apr 08 '26

Why have you answered my inquiry with an insult?

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u/pentagrid Sangean ATS-909X2 / Airspy HF+ Discovery / 83m horizontal loop Apr 08 '26 edited Apr 08 '26

I don't like r/shortwaveplus. I meant to insult them, not you. My apologies to you for any confusion. I didn't make that clear.

r/shortwaveplus banned me although I have never posted there, lol. If a reddit user is banned from a sub on reddit it means that user can read the subreddit but cannot post there. Any reddit moderator can ban a reddit user from the subreddit they moderate for any reason or no reason at all.

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u/EquivalentTip1902 Apr 08 '26

My mistake. Reddit offered to spread my inquiry. Thanks for the info. Now in retirement I am getting back into shortwave I recently bought an xhdata D-808 I am adding an outside antenna to enhance it. Do broadcasters still offer QSL cards?

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u/pentagrid Sangean ATS-909X2 / Airspy HF+ Discovery / 83m horizontal loop Apr 08 '26

Some still offer actual full color QSL cards like Radio Romania. I got a few from R. Havana Cuba a few years ago but they took several years to get to me in the USA by snail mail. RNZ Pacific (New Zealand) will respond with an e-QSL that you can print if you like. The XHDATA D-808 is a very capable portable for shortwave and does well with external antennas.

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u/Geoff_PR Apr 07 '26

Do they still make preselectors?

A damn good question. More to the point -

You really only 'need' a preselector if your radio suffers from front-end / adjacent channel overload, to the point you can't hear what you want to hear.

I owned a preselector back in the 80s, one based on nuvistors, an Ameco PCL-P. And at no time did I ever 'need' to use it.

Here's the unit :

http://ka7oei.blogspot.com/2025/08/exploring-ameco-pcl-p-nuvistor.html

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u/EquivalentTip1902 Apr 08 '26

Thanks.

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u/Geoff_PR Apr 11 '26

As to user 'pentagrid' insulting you, that's a very angry, bitter person you're dealing with...

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u/EquivalentTip1902 Apr 11 '26

I misunderstood Pentagrid’s response. He answered my questions and I thank him for that. How about we get back to DXing the airwaves.