Many because of SWLing Submit contributor, Bob Colegrove, who shares the next visitor publish:
As requested by Bob Colegrove
Let’s suppose you’ve been listening to radio for some time. Consciously or not, you’ve most likely favored a variety of AM, SW, or FM frequencies. These are areas the place you go to DX or simply hearken to your favourite stations. One space I appear to maintain returning to is the very backside of the medium wave band, roughly 530 kHz to 600 kHz. With the comfort of in the present day’s digital radios, I’ve consciously pushed the envelope considerably decrease.
The primary motive for specializing in that frequency vary is the problem. Within the very starting there didn’t appear to be a lot on the excessive decrease finish of the AM broadcast band. Rising up in Indianapolis within the ‘50s, the native stations have been all on the higher finish of the mediumwave dial. WXLW held down 950 kHz – decrease than that nothing. I might say the stator plates on the variable capacitor obtained very dusty, by no means being closed any additional than that on many radios.
One other problem was sensitivity. In analog instances, the sensitivity of a tuned circuit had some falloff because the inductance/capacitance (L/C) ratio decreased. Sensitivity is highest with the variable cap open on the excessive finish of the band. As you tune decrease by growing capacitance (inductance remaining fixed), the Q and consequently sensitivity drop off – not dramatically, however considerably.
Lastly, not all previous analog radios tuned to 530 kHz; some have been even challenged to tune 540 kHz. By performing slightly mischief with the alignment, I may typically enterprise into unknown territory.
This was all a part of the problem. So, what may I do to coax some exercise out of the underside of the band? I spent many hours poring over Invoice Orr’s Higher Shortwave Reception (Radio Publications, Inc., Wilton, CT, First Version, 1957) and tweaking caps and coils making an attempt to squeeze the previous few kilohertz and microvolts out of my radios. This train fascinated me and have become a pastime inside a pastime. If I could also be allowed a self-deprecating apart right here, the primary time I took a radio out of the cupboard, I simply assumed that each one these alignment screws have been free, and dutifully torqued them down. The alignment drawback will not be comparatively complicated with in the present day’s digital receivers. Word, I didn’t say it was unimportant.
I nonetheless are likely to favor the underside of the medium wave band. Under is an inventory of my catches over the previous couple of years. It’s only a pattern of what one may hear by informal listening over time. Highlighted stations are heard throughout daylight. That is NOT supposed to impress anybody, fairly it’s hopefully a stimulus on your personal efforts.
As one other attraction of the decrease mediumwave band, you will discover a potpourri of stations. Apart from common North American broadcasting stations, one may presumably hear an occasional high-powered trans-Atlantic station which isn’t synchronized with the ten kHz spacing. 530 kHz is attention-grabbing. It’s not used within the US by business broadcast stations. As a substitute, stations from Canada and Cuba at roughly orthogonal instructions from me are recurrently audible at evening on this frequency. Thus, the radio is tuned by merely rotating the antenna. 530 kHz can also be dwelling to a number of Vacationers’ Data Stations (TIS) all through the nation. Query: How will this long-time service fare if vacationers don’t have AM radios of their new vehicles? Lastly, the very backside of the frequency vary nonetheless incorporates a couple of holdouts of non-directional beacons.
Frequencies under 530 kHz most likely put a pressure on the medium wave bands of previous radios, however they’re possible no drawback on most digital radios having each LW and MW protection. As talked about, there are a couple of non-directional beacons down there. They’re Morse coded utilizing amplitude modulation. I’ve discovered inserting the receiver in SSB mode makes detection a lot simpler, because the heterodyne from the provider might be heard nicely earlier than the sign is robust sufficient to provide any audio. These beacons usually fade in for temporary intervals of time after which fade out like passing comets.
My most up-to-date catch was experimental station WI2XLQ, 486 kHz, throughout its annual Fessenden Occasion on Christmas Day and once more on New Yr’s Day. See https://swling.com/weblog/?s=Fessenden+ . The expertise was not the armchair listening high quality one may count on from FM or the Web. As a substitute, it was weak and fraught with atmospheric noise. The station got here in periodically, then disappeared, briefly, DXing to its highest diploma of satisfaction.
The antenna is the important thing to good reception, and there’s no exception to this rule on the decrease finish of the AM band. A few years in the past, I switched to an indoor, resonant loop antenna. The selectivity, directional properties, and noise rejection of a loop antenna on this frequency vary are very good. The determine under reveals my 40-year-old loop antenna, which remains to be utilized in its authentic kind. It tunes from ~485 kHz by means of ~1710 kHz in two bands. The antenna can rotate 360 levels horizontally and 90 levels vertically. Additional, it’s mechanically balanced to stay in any place with out locking. For these not inclined to building initiatives, the Tecsun AN-100, AN-200, and Terk Benefit will carry out fairly nicely by means of inductive coupling with a transportable radio’s ferrite bar antenna.
As all skilled medium wave DXers know, for achievement it’s essential to have endurance, “set a spell,” and let the radio do its factor. Radios live organisms, form of like cats, very unbiased at instances, and can allow you to hear solely what they need you to listen to. On many channels, stations will come and go over time. When you’re fortunate, you may catch an ID; missing that, you may have the ability to establish it by the format or community. You may attempt to examine the contents you hear on the radio with what you possibly can hear on-line both over the station’s web site or through streaming websites corresponding to TuneIn, iHeart, or Radio Backyard. There could also be a delay between the Web stream and the reside sign.
While you really feel you’ve exhausted the probabilities, there’s nonetheless extra. Flip the antenna 90 levels and begin over. You’re solely half completed with that frequency. Don’t neglect a headset or earbuds.
What’s the subsequent difficult rung on the limbo bar? Nicely, presumably the 633-meter ham band, 472 to 479 kHz. I’ll need to pad the previous loop with a small capacitor to tune down there.
What’s your favourite nook of the dial? Why?
