Potential Ultralight Radio – Grundig Mini 300
Steve Ponder N5WBI <n5wbi@...>
Radio Reviewed: Grundig Mini 300 (unmodified)
Radio Used for Comparison: Eton E-100 (unmodified)
Description of the Grundig Mini 300
Frequency Coverage: AM (525-1710 kHz), FM (88-108 MHz), SW1/49M (5.95-6.20 MHz), SW2/41M (7.00-7.30 MHz), SW3/31M (9.50-9.95 MHz), SW4/25M (11.60-12.10 MHz), SW5/22M (13.60-13.80 MHz), SW6/19M (15.10-15.80 MHz), and SW7/16M (17.50-17.90 MHz).
Size: Fits in your pocket. Dimensions are 2.6 x 7 x 1.2 inches (65 x 170 x 23 mm). Weight without batteries is 4 ounces (127 g).
Tuning: Analog with digital display. Tuning is accomplished by means of thumbwheel on right side of radio. MW tunes in 0.5 kHz increments. FM tunes in 50 kHz increments. Shortwave tunes in 5 kHz increments. Bands are selected by a 9-position slide switch on the left side of the radio. FM Stereo is available through the headphone jack, located on the left side of the radio just below the band switch.
Antennas: FM and Shortwave reception use a telescopic antenna that is located on the left side of the radio. There is a molded part of the radio case that extends approximately 2.125 inches (57 mm) above the top of the radio to protect the antenna. Unfortunately, it also prevents the antenna from swiveling or turning. You must occasionally orient the entire radio for best FM reception. Fully extended, the telescopic antenna adds another 19.75 inches (502 mm) to the overall height of the radio. This often causes the radio to tip over. The AM band uses an internal ferrite bar loop antenna oriented parallel to the top of the radio.
Power Source: The radio operates on 2 AA batteries. There is no provision for an external DC power adapter.
I checked the Mini 300 for (1) sensitivity and (2) selectivity using the Eton E-100 as my base for comparion.
For the sensitivity portion of the review, I selected two stations on the high end of the AM dial, one a local TIS station on 1610 kHz, the other a semi-local on 1460 kHz. I also selected two stations on the low end of the AM dial, both semi-locals, one on 550 kHz, the other on 560 kHz. I also threw in another TIS station on 830 kHz and a station in a neighboring state on 870 kHz that can be heard well at my location. The sensitivity review was performed during the middle afternoon, before local sunset started affecting the signals.
For the selectivity portion of the review, I chose two local stations, one on 740 kHz, the other on 1480 kHz, that are (IMHO) notorious for splattering their immediate adjacent channels at night. This is due, not to the fault of the stations, but to the quality of the radio - hence the reason for the test. So, I compared the Mini 300 and the E-100 on 730, 750, 1470, and 1480 kHz at approximately 2 hours after local sunset in order to give the station's signals time to settle down into their nighttime strengths.
To "quantify" my completely subjective evaluations, I used the same scale that Gerry Thomas of Radio Plus uses in his evaluations:
5 - Local (all background noise "quieted")
4 - Easily Readable, but not like a local
3 - Readable, but with some effort
2 - Intermittently readable
1 - Present, but not readable
0 - Not detectable
Based on the fact that my totally non-scientific results returned over 50% in both categories (sensitivity and selectivity), I think the Grundig Mini 300 world be a worthy addition to the list of Ultralight Radios!
Disclaimer: The opinions stated in this review are myown. I personally own all of the radiosthat I reviewed. Measurements,calculations, and estimates were performed strictly by ear and reflect my bestjudgment alone.
73 and Great DX,
Hey Steve:toggle quoted messageShow quoted text
Thanks for the Grundig Mini 300 review! I have seen this unit around, and
have always wondered how it performs. The analog/digital tuning which
allows 1 khz fine tuning would be a nice thing to have. Your testing
methodology is great - I wish I was so thorough :-).
It looks like the 300's no substitute for the "Jumbo Shrimp" Eton E100 but
still manages to hold its own. Given the uneven sensitivity results, I
wonder if an alignment would perk it up?
As for selectivity, since the E100 is the stock selectivity champ, it
wasn't a fair fight: do you have a Sony SRF 39 or 59 to compare
selectivity with? That may be an intersting quick comparison. (***Hey
Gary/John/Guy*** - I wonder if the 300 would accept a Murata filter...)
I look forward to when you get the time and energy to keep going on your
stable of Ultralights to see how the other little guys fare!
73 - Kevin S
Bainbridge Island, WA
Based on the fact that my totally non-scientific results returned over
Thank you for your efforts in reviewing the Grundig Mini 300. The E100 itself will be reviewed as part of the Midsummer Ultralight Radio Shootout, along with the Sony SRF-M97V, SRF-S84, SRF-M37W and DT-400W.
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John H. Bryant <bjohnorcas@...>
Thanks for the excellent review of the 300. I was interested enough that I went to the eham reviews to read what other users had to say and most were reasonably positive. However, one user who seemed knowledgeable noted quite a number of images and even some breakthrough from shortwave broadcasters. He was unsure as to whether he had a defective, mis-aligned unit or whether this ight be a characteristic. It might be worth taking a look at that problem, if you didn't. Here are the comments:
My Grundig Mini 300PE performs very well with the exception of the MW (standard AM) band. My set experiences poor image rejection. Ex. a station on several miles away (WTOP Wheaton MD) 1500Khz can clearly be heard at a tuning of 590Khz. That tells that this radio uses an IF freq. of 540Khz.
I was surprized initially at all the whistles and hetrodynes that occurred at night time at frequencies above 1000Khz. With some investigation, I've discovered that this radio is receiving short wave transmissions from the 5 to 7 Mhz band. At a tuning of 1082.5Khz, WWCR on 5.070Mhz is tremendously strong. By some simple arithmetic calculations, it appears that the third harmonic of the local oscillator (at the 1082.5Khz tuning) is at 4.62Mhz--below 5.070Mhz by the IF frequency of 450Khz. For the math to work exactly right, the exact receiver tuning would need to be 1.090Khz, so that the radio's frequency display may be a bit off by -7.5Khz. Similarly, I receive other shortwave stations where there is no conflicting AM broadcaster. The FM/SW telescoping antenna seems to be active on MW; touching it attenuates reception. It's as though there is no front end tuning.
This is poorer AM performance than a '60s shirt pocket six transistor radio.
It's hard to believe that this performance is typical for this radio. If I got a bad one, someone please say so.
No one responded to this man, either way.
Thanks for your work!
I finally opened the case of my Mini 300 to take a look at what's
inside, but made no adjustments. My guess is alignment would similar
to the E100.
To disassemble, first remove three screws (two in the battery
compartment) and slowly lift the back from the bottom slowly to detach
it from a hook at top right (from the back). The hook could be broken
if not done correctly. Once unhooked, the back is free to set aside.
Now remove the two screws holding the main circuit board to the front
of the case. Below it you will notice a second circuit board attached
to the front case above the speaker. It's the frequency
counter/display circuit and there's no reason to remove it.
There is an approximately 5 x 0.7 cm. (1.9" x 0.27 ") ferrite bar
antenna at the top of the main circuit board. It looks like a shorten
version of the one in the E100. Like the E100, the antenna coil is
held in place with wax, so the 600 kHz adjustment should he easy. I
didn't identify the 1400 kHz adjustment point - it's one of the eleven
on the front of the circuit board.
To reassemble the receiver, first secure the main circuit board to the
case front ensuring the band switch is in its correct position. Then
hook the case back to the front checking to see the battery
compartment springs fit back into place. Finally replace the three
screws holding the two halves together.
My opinion is the tuning control on the Mini 300 keeps it from being
used for serious DXing. It's extremely tricky to use and takes a very
practiced thumb or forefinger to get it right on the desired
frequency. A 3.5 (1.4") cm. tuning control wheel is coupled directly
to a small variable capacitor. It would probably benefit from some
type of venier tuning apparatus.