Monday, March 25, 2019

The DXer's Light Source

Not a radio but something you might need if you DX at night. The Thrunite Ti3 V2 Keychain Flashlight.

I do a lot of my DXing in the wee hours of the night. With the warm weather of Arizona year-round, most of that is done outside too. Many of the modern digital portable radios have dial lights, but even these don't have lighted buttons. The older portable radios didn't generally have dial lights at all. The nighttime DXer needs a way to illuminate their radio for tuning and settings changes.

Bulky flashlights are out. Who needs 'em. They take up too much room and are too heavy. Penlights were traditionally cheap and fell apart quickly and didn't give much light in any event. And the bulbs constantly failed. Maglites had that weird little bulb that you could never find.

About a year ago I came across a review touting the Thrunite Ti3 V2 Keychain Flashlight. It's tiny and smaller than the palm of your hand. It's also LED, so no bulb to burn out. It takes a single AAA battery. It has three light intensities. And it will light up your backyard on the highest setting. The lower two settings are perfect for radio work in the dark. I bought one.

This guy has a great review of this unit on his backpacking site: backpackinglight.com

There is no cheap Harbor Freight click switch to fail on this light. It works by rotating the barrel to switch the light on. Twist once - dim. Twist twice - medium intensity. Twist three times - high intensity. And a secret setting not documented - twist six times in quick succession and the light flashes on and off in a strobe fashion.

This is the coolest, best penlight I've ever owned, so much so that I've since bought several for Christmas and birthday gifts. It is rock solid machined aluminum and built like a tank. It's priced right at about $14. You will love it and use it daily if you are a nighttime DXer sitting in the dark.

You can see it on Amazon right here:

See it on Amazon

I don't normally push products on this site, but I can't help it on this one. It's the perfect item for the nighttime DXer.







Friday, March 15, 2019

Review Of The Panasonic RF-562DD Receiver

Partly based on Jay Allen's positive review on his Radio Jay Allen web site, and also because it's analog and not DSP-based, I ordered this radio. One of my favorite older radios I no longer have was the Panasonic RF-565, similar in size. It was an good performer. Additionally, the RF-562DD has that sharp retro look from the early 1960s. It's reputed to be pretty hot. Let's see how it stacks up.

This a 3-band radio - MW, FM, and shortwave. The Panasonic RF-562DD claims to be the "new" RF-562D. I can find no obvious differences between it and the RF-562D. It could possibly be engineering changes. The radio seems to be manufactured for a foreign audience, that is, foreign to the western hemisphere.

The radio was purchased from Amazon. Price $48.99. If you order one, be sure to have them repackage it in a second box. The radio itself is packaged in a bare-bones shirt-cardboard type box as shown in the picture below. I know of one gentleman who ordered it and it was shipped in this box. He was surprised it survived the trip. Secondly, you don't want the general public knowing what's inside your shipment.

RF-562DD What's in the box - showing radio in leather case

I'm not sure when this radio was introduced. I've seen references to it as early as 2011. The radio is an analog design, and uses a monolithic CD2003GP IC chip for virtually all superhet stages, similar to the earlier Sony radios like the SRF-59 and ICF-S10MK2. The CD2003GP is an excellent single chip AM/FM radio requiring very few external components. The IC has all the building blocks required for a desirable AM/FM receiver.

QUALITY AND ERGONOMICS

The large, side-to-side slide rule dial extending across the top of the radio only tunes 530 - 1605 KHz on the mediumwave band, so North American buyers beware. I was able to get to 1660 KHz on my unit. The face has a sort of a magnifier bar over it to enlarge the frequency readout, a nice touch. It also has a retro "Log" scale, 0-10, another nice touch. Lacking is a dial light. The FM band covers 88 - 108 MHz. The single shortwave band covers 4.75 - 18 MHz.

The radio is bare bones, black and silver, and all plastic. It's size is 210 x 120 x 65 mm (8.25 in x 4.75 in x 2 in). Panasonic has included a nice faux leather case which fits snugly to the radio. It reminds you of the first transistor radios of the 1950s and 1960s which all came with leather cases allowing their controls to be accessed through cutouts in the cases.

The external antenna is a single telescoping whip at 32 inches long. It does not swivel. The whip is used for FM and shortwave reception.

The radio takes two "D" cell batteries and they will last nearly forever, especially if the radio is used with earphones. Panasonic claims upwards of 280 hours in AM mode. It does not come with an AC-mains power source. You can supply your own if you have a 3.6 VDC wall wart @ 300 ma, positive center pin. Also supplied is a vinyl carrying strap which can be affixed to the top of the radio. There are no other accessories besides the case and carrying strap. There is no manual, though with such a simple radio as this you surely don't need one.

The front-facing speaker is 8 cm (3.15 in) in size. Power output is 800 mw, more than adequate for room-filling volume. Only two controls protrude through the case on the front - a tuning dial and a switched volume control which also powers the radio on. At the back is a 3-position slide switch which selects the band. On the right side of the radio are the 3.6 VDC input jack and a monaural mini earphone connector. If you use stereo earphones or earbuds, you will need to purchase a monaural to stereo adapter. Radio Shack, oh how we miss you.

I will register two dings at the outset, one for the lack of dial light, and one for the monaural earphone jack, even though FM does not receive in stereo. Virtually all earphone and earbuds today are stereo and have stereo connectors. It would have been a simple matter to use a stereo jack and wire the channels in parallel to avoid the use of an adapter. The lack of dial light requires you to carry a small penlight with you if the radio is used in the dark.

Primarily I'm a mediumwave DXer, so we will cover mediumwave observations with this radio in this article. A few comments on its FM and shortwave capabilities are at the end of the article.

Panasonic RF-562DD - sans leather case

SENSITIVITY

The radio comes with a nice 140 mm (5.5 inch) ferrite rod antenna for mediumwave. This is a superhetrodyne, so there are a couple of coil windings on the ferrite. AM I.F. frequency is 455 KHz. FM I.F. frequency is 10.7 MHz. Sensitivity of the RF-562DD is nothing short of amazing for its size and mediocre build quality. I've done both skywave and daytime sensitivity tests from western Arizona, comparing signal strengths with various radios I own. Using a 5-star ranking system, this is where I'd place it among my selected receivers.

Sensitivity Breakdown

Panasonic RF-2200    5.0 *****
CCRadio EP Pro       4.5 **** 1/2
Panasonic RF-562DD   4.0 ****
Sangean ATS-909X     3.5 *** 1/2
Tecsun PL-880        3.0 ***
Tecsun PL-600        3.0 ***
Sony ICF-S10MK2      2.5 ** 1/2
Sony SRF-59          2.0 **

Despite reports of low sensitivity of the Sangean ATS-909X, mine was hot right out of the box, and was my best performer until the Panasonic RF-2200 and CCRadio EP Pro were acquired. Now the RF-562DD bests the '909X by just a little.

RF-562DD circuit board showing ferrite antenna

NULLING ABILITY

The RF-562DD has good nulling ability, better than many. Nulls are sharp and well defined. Very helpful for skywave DXing.

A difficult station to receive here at night is Phoenix's KFYI-550, using 1 KW at a distance of 130 miles. The groundwave signal is weak and of course the skywave at this distance is almost non-existent. Other low-level marginal signals, notably Colorado's low power nighttime KRAI-550 at only 500 watts best it. I sometimes don't even hear KFYI on the CCRadio EP Pro. I can hear KFYI with the RF-562DD, albeit weakly. I believe the difference here is the better nulling ability. I'm able to bring down KRAI-550 at Craig, Colorado just enough for Phoenix to surface. It is equal to or slightly better than the EP Pro in its nulling ability and that makes all the difference.

Nulling Breakdown

Panasonic RF-2200    5.0 *****
Panasonic RF-562DD   4.0 ****
CCRadio EP Pro       3.5 *** 1/2
Tecsun PL-600        3.0 ***
Tecsun PL-880        3.0 ***
Sangean ATS-909X     3.0 ***
Sony SRF-59          2.5 ** 1/2
Sony ICF-S10MK2      2.0 **

SELECTIVITY

Slightly above average. Better than the Sony ultralights mentioned, but not as good as the bigger portables. The radio's extreme sensitivity appears to be about maxed out for this chip, close to the overload point. I have coupled the radio to an 18 inch passive loop and it couples extremely well. If coupled too closely to this loop the RF-562DD can be easily overloaded by nighttime skywave signals. This is not all bad in the case of this radio. Loose coupling works best, and since it responds well at various coupling distances it is often better than the DSP units which are notoriously bad-couplers.

Selectivity Breakdown

Panasonic RF-2200    4.5 **** 1/2 (2 bandwidths)
Sangean ATS-909X     4.0 ****     (2 x I.F. DSP filtering)
CCRadio EP Pro       3.5 *** 1/2  (2 DSP filters)
Tecsun PL-880        3.5 *** 1/2  (4 DSP filters, surprisingly low)
Tecsun PL-600        3.5 *** 1/2  (2 bandwidths)
Panasonic RF-562DD   3.0 ***      (1 bandwidth)
Sony SRF-59          2.5 ** 1/2   (1 bandwidth)
Sony ICF-S10MK2      1.5 * 1/2    (1 bandwidth)

TUNING

Tuning is rather sharp and requires a deft touch, particularly above 1000 KHz. The dial has a bit of tightness to it, possibly because it's new, and isn't silky smooth like the analog dial of the CCRadio EP Pro. There's a slight amount of backlash but that's easily gotten used to, and expected. It's a joy to tune through a signal's peak again with the analog tuning. Tuning is easier below 1000 KHz as the stations are more well separated. Remember that analog tuning tunes in a roughly logarithmic scale, wider at the lower end and scrunching the band closer together at the higher end. This makes stations quite close together above 1000 KHz. In that area it takes a finer touch with this radio, and is a bit challenging with the stiff dial.

Dial accuracy is fairly accurate on this radio, better than the CCRadio EP Pro, but as with most analogs (the RF-2200 is certainly an exception here!) it can be difficult to know exactly to which channel you are tuned to. Having a digital spotter radio nearby can be a big help, particularly in the daytime with fewer signals and bigger gaps between stations. At night, if you DX consistently like I do, you get to know the band almost like a fingerprint.

My particular unit had an intermittent tuning glitch at the lower end of the dial where the radio suddenly went dead of signals at about 600 KHz. Tapping the front of the radio or the tuning knob fixed it. It wasn't a power issue because I could still hear low level hiss through the speaker or earphones. I initially suspected a bad tuning capacitor or broken circuit board path. After opening the case, it turned out to be a misplaced litz wire contacting one of the I.F. cans. After moving the wire the problem disappeared. This points to continued quality control issues in today's cheap (and not so cheap) consumer radios.

AGC

By my taste, this radio has great AGC characteristics, those being very fast attack and fast decay. I believe these are the best for DXing. They can be tiring to the ear over long listening periods, however, for weak signal work you need AGC which responds and relaxes quickly, revealing very weak background signals, buffeting, echo, and subtle but quick variations in strength and quality. Just one man's opinion.

Old timers will remember the receivers of many years ago having a switchable AGC system - slow, medium, fast, and off. The DXer often switched the AGC off and used the RF gain control to control signal strength. With the AGC off you heard everything, even extremely weak, on-channel signals mixed with the stronger ones. Fast AGC is the next best thing to the "off" mode. The RF-562DD has excellent fast AGC. Weak signals are apparent under very strong ones.

AUDIO

If you love treble you will love this radio. Many may find the audio rather harsh and tiring. I do, and I'm more tolerant than most. Yet the voice intelligibility is good - no mushy or muffled audio here like found in some radios, notably some Sonys (ICF-2010 can be this way) and the Sangean ATS-909X on the narrow bandwidth setting. I will agree that the audio section could use just a little more bass. I've noticed some occasional (but minimal) audio distortion on some signals, almost as if the audio section is starting to overload. This is usually straightened out by a tweak of the tuning dial. It is not RF overload.

SIGNAL SPURS AND IMAGES

I did a quick check and did not find any blatant signal spurs. No bleed-through images of mediumwave stations were detected on the shortwave bands. That's a good sign that the selectivity is adequate.

NOISE

The RF-562DD itself has a low noise floor which is good for DX and weak signal work. I found it more susceptible than average to digital noise and hash, however. Keep it away from wall warts, TVs, computers, and other appliances.

THE RF-562DD IN ACTUAL USE

Reception of KRLD-1080 out of Dallas, Texas at 1017 miles distant can be a little difficult on some receivers here in western Arizona due to nearby and adjacent-channel KNX-1070's IBOC sidebands. The Los Angeles, CA station is only 237 miles distant and transmits with 50 KW. Being so close, KNX doesn't fade down much and IBOC hash can be extremely strong on 1060 and 1080 KHz. Radios which make the grade here are the good nullers and those with extra I.F. bandwidth selectivity. The RF-562DD does a good job due to its good nulling ability. The Sangean ATS-909X does a good job due to its design employing DSP selectivity in the I.F. stage. The Tecsun PL-880 with its multiple DSP bandwidths is also a winner.

Another good indicator of DX ability here is the reception of Montana's KMON-560 at Great Falls (5 KW). Directionally, it is sandwiched between Denver's KLZ-560 (5 KW) and San Francisco's KSFO-560 (5 KW). Only about 90 degrees of aperture exists between these two. KMON is right up the middle to the north. KSFO's two tower pattern pushes to the southwest, and only delivers about 500 watts in my direction at a distance of 537 miles. KLZ in Denver at 667 miles does better and it's directional pattern pushes about 2400 watts towards me. Little KMON at 963 miles is a different story, however. It has a near-perfect cardioid pattern to the northeast and I am exactly in a deep notch at the back end. Only about 50 watts is pushed in my direction. This is a tough one to log. You must sit on this frequency for awhile and wait for San Francisco and Denver to deep fade. If you are lucky, and Montana's KMON is coincidentally at a good fade up, you might hear it. I have heard this station with the RF-562DD and the CCRadio EP Pro. I attribute this to sensitivity and superior nulling.

A receiver's selectivity is severely tested here on 650 KHz and 730 KHz due to the 50 KW blowtorch station pairs KFI-640 Los Angeles, CA / KTNN-660 Window Rock, AZ and KDWN-720 Las Vegas, NV / KCBS-740 San Francisco, CA. These are the top four strongest stations here at night. Reception on 650 KHz and 730 KHz is easily handled by the Panasonic RF-2200, the CCRadio EP Pro, and the Sangean ATS-909X. The RF-562DD manages, doing a little better than the ultralights. However, at extreme fade up of these blowtorch signals, some side splatter is evident on 650 KHz and 730 KHz. This is not unexpected on a radio in this price range.

FM

Though I'm not an FM DXer or FM aficionado, the FM section of the RF-562DD seems a little above average in sensitivity. I had some minor overload problems when tuning near the frequency of a local 100 watt FM station. I was within 1/2 mile of the station.

When tuning across the FM band, an annoying treble hiss on a station's audio becomes present as you tune off the station's center towards its edge.

Note that audio output to the headphone jack is not stereo.

SHORTWAVE

The single shortwave band (4.75 - 18 MHz) seems almost an afterthought on this radio. Performance is poor though sensitivity is not bad. Tuning is very delicate to say the least and almost impossible to land on a station. Practice helps. I wish Panasonic had left shortwave off and reduced the price of the radio by $20.

Don't buy this radio expecting great or easy shortwave reception. Consider a CCrane Skywave SSB, Tecsun PL-880, Sangean ATS-909X, or Tecsun PL-600 series instead.

SUMMATION

This radio is an nice mediumwave performer with great sensitivity, better than average selectivity and nulling ability. It could serve as your MW DX machine and even more if enhanced with a small passive loop (12-18 inches would be ideal).

Great AGC characteristics.

A nice retro look with faux leather case allowing access to the controls.

Easy on batteries but no AC adapter.

Audio might be considered harsh as it has overwhelming treble, reminding me of the original Tecsun PL-600's audio. The audio is not for everyone.

Tuning can be a little delicate, particularly on shortwave. Shortwave in general is poor. FM is adequate. Do not buy for shortwave.

Other minuses - no dial light and headphone jack is monaural only. Requires a mono to stereo adapter.

All plastic and somewhat cheap looking. I feel this radio is $20 over-priced, mainly because of the near useless shortwave inclusion.

Bottom line: It's not an Ultralight, but if you want an inexpensive mediumwave, analog DX radio that's more sensitive than the run of the mill DSP Ultralights, this could be your radio for a $50 bill. It is retro and has a good look about it. Beware of harsh audio.

Todderbert did a nice video review of this radio on his channel. Be sure to check it out and his other reviews.


The CD2003GP Monolithic AM/FM receiver chip