Re: Potential Ultralight Radio – Grundig Mini 300

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!

John B.
Orcas Island, WA, USA
Rcvrs: WiNRADiO 313e, Eton e1, Ultralights
Antennas: Two 70' x 100' Conti Super Loops, West and Northwest

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