Equipment Reviews, July 1998
The Lowe HF-150E Communications Receiver
Since its introduction in 1992, the Lowe HF-150 has won kudos for its small size, easy operation and excellent sound. It offers good performance for program listening and reasonable DXing capability. Although it has only two IF bandwidths, the selectable sideband synchronous detector can be quite effective in rejecting interference. When equipped with internal batteries and an accessory whip antenna it is at least transportable, if not the equivalent of a true portable. In the past, it has been fairly priced and offered good value.
The Fly in the Ointment
The only really significant flaw in the design of the ‘150 was the lack of bandpass filters in the antenna input circuitry of the receiver. The first mixer circuitry is exposed to all signals in the receiving range of the receiver–5 kHz to 30 MHz–which can result in overloading problems when the receiver is used in the presence of strong local MW stations or with large outdoor antennas. This front-end overloading can manifest itself as increased noise, local signals mixing with shortwave signals and “ghost” signals.
The problem was significant enough that Lowe introduced the PR-150 preselector to provide front-end selectivity. The PR-150 was a good unit, but was costly (over $300) and, being the same size as the HF-150, greatly reduced its portability. Lowe has addressed this problem with the release of the HF-150E, or “Europa” version.
The Europa has bandpass filters added to the front-end. There are five filters covering the ranges of: < 1 MHz, 1 to 5 MHz, 5 to 10 MHz, 10 to 20 MHZ and 20 to 30 MHz. These filters are automatically selected as the receiver is tuned to the respective ranges.
Do They Help?
Incorporating these RF bandpass filters should theoretically reduce spurious responses and noise. I compared the ‘150E to my early model ‘150. When the original ‘150 was connected to my 90/60 meter parallel dipole, there were several frequencies below 3 MHz which had images of local broadcasters. With the ‘150E , there were no audible images present, but there was increased noise on the same frequencies. The image problem was cured when the -20 dB attenuator was switched in with either receiver. Images were not a problem with either receiver when a twenty foot outdoor wire antenna was used. So, the input filtering is a help on the HF-150E, but listeners (with just about any receiver) with large outdoor antennas should consider adding a broadcast band rejection filter (high pass filter) to their listening setup and/or a variable-step attenuator, such as the MFJ-762. In comparing the manufacturer’s specifications for the two versions, the third order intercept point is specified as +18 dBm for the HF-150E and +7 dBm for the ‘150 (narrow filter at 50 kHz spacing).
Any passive filter will introduce some degree of insertion loss, so I was interested in seeing if there was any difference in sensitivity between the two receivers. The manufacturer specifies a sensitivity figure of less than one microvolt in AM mode over the range of 500 kHz to 30 MHz for the original HF-150 and less than 2 microvolts for the “E” version over the same range. I checked these figures by using the standard methodology of a 10 db signal + noise/noise ratio with a signal 60% modulated with a 1 kHz tone, with the receivers in AM mode and with the wide filter. I found that the original HF-150 was about 0.5 microvolts more sensitive across the HF spectrum, however, the HF-150E was within specification of less than two microvolts throughout the HF spectrum, and was typically in the range of one microvolt. I think that the higher sensitivity of the original may not be a virtue, given the radio’s susceptibility for overloading. I don’t think that this difference is significant, and switching in the pre-amp on the HF-150E improved the sensitivity to the level of the ‘150 without pre-amp. I didn’t measure any difference in the ‘150E’s sensitivity at the filter crossover points, i.e. at 5, 10 and 20 MHz, as compared to the midpoints of the RF filters’ passband.
Where Am I?
One other complaint that users had about the original HF-150 was the lack of dial lighting, which meant that the frequency display was invisible in the dark. Lowe offered a do-it-yourself backlight accessory, but it appeared from the instructions that installing the kit involved a high risk of cracking the radio’s LCD display. The HF-150E includes a very nice orange dial backlight. Now, the complaint is that there is no way to disable the backlight to cut back on battery drain, although this should be minimal.
The only other discernable difference in the 150E is that the case and front panel are black. There is a Gothic scripted “Europa” label in the lower left corner of the front panel. The accessory lineup has been changed for the ‘E–the AK-150 accessory kit, which included a carry strap, shoulder strap and whip antenna has been discontinued. A whip antenna, MPW, is available. The outboard audio processor/speaker/S-meter is to be replaced with an outboard S-meter, the SM-1. The standard keypad is still available (and highly recommended), but there are plans to introduce the enhanced KPAD-2, which will allow mode entry and memory manipulation from the keypad.
The other major complaint I have about the Lowe HF-150E is its price. At Universal Radio, the current price is $749, which makes the ‘150E less of a good value, relative to the original. There is hope that this price will come down somewhat, which will make the ‘150E more attractive to the consumer. The US distributor for Lowe is EDCO, 325 Mill St., Vienna, VA 22180; (703) 938-8105. Thanks to John Wagner for the gracious loan of the review receiver.