Showing posts with label Nordmende. Show all posts
Showing posts with label Nordmende. Show all posts

Tuesday, January 27, 2015

NORDMENDE GLOBETRAVELER II

I like Nordmende. Their radios just seemed to ooze quality. The Globetraveler series exemplified that. It is the epitome of what was considered a high end portable radio in the late 1960s: well built, beautiful sounding and feature-laden.
Nordmende Globetraveler II

At the time, the Globetraveler would have been way out of my league in terms of affordability. Besides, I was just a kid then. Today, however, a gently used version can be found online quite cheaply. With a little bit (hopefully) of effort, it can be made to look and run like new.

Such is the case with my Globetraveler II. It's the North American equivalent of the European Globetrotter TN6000. Its best feature is a bandspread tuner that allows you to tune specific shortwave broadcast bands individually and comfortably without the "touchiness" of a tuner that covers all bands in a single sweep of the dial. These bands range from 13m to 80m. Not sure why they included an amateur radio band, because as far as I know, broadcasting never took place in the 80m band.
 
Besides the need for cosmetic cleaning, here were the issues with mine:
  • Shortwave bandspread tuner non-functional on some bands and band switching was noisy. This was major for me, as the bandspread tuner was what set this radio apart from many others.
  • Audio was slightly distorted (crossover distortion).
  • The a.c. socket uses a silly switch that cuts out the battery when an a.c. cord is plugged in. Silly because the lever that actuated the switch often stuck, cutting out the batteries even when the cord was pulled.
  • Power supply needed re-capping. No surprise there after 45 years, but ripple persists. Since I prefer battery power, this is not a big deal for me, but I suspect a leaky diode or two in the bridge rectifier. Later.
  • A dangerous carry handle that likes to unhook easily on its own. Caution with this one!
The bandspread tuner was not an easy fix. The first approach is always to try to clean all switches. I used a run-of-the-mill switch and potentiometer cleaner on the tuner's wafer sections. Big mistake. The tuner became less and less functional the more I sprayed until it totally failed. By this point, my mind went straight to the hardest solution, and I began to believe the local oscillator stage failed. The thought of accessing this tiny board gave me a slap of reality, and I bit the bullet and bought a decent but expensive cleaner (DeOxit). A couple of sprays later, it came back to life. The wires in this tuner are very delicate, so after I discovered a wire I had broken when probing the tuner, all bands worked again. After the cleaner dried, I re-tuned as many coils as I could access. This tuner is designed for manufacturing, not service. Access to components is sometimes horrible - a nightmare in fact (see photo).
Bandspread tuner from hell

Fixing the audio issue was easy. De-solder a jumper, insert ammeter, and tweak the output stage bias until about 6mA is achieved.

Finally, as with other radios reviewed here, I performed a subjective comparison with my old stalwart kitchen radio - the Telefunken Partner 500.

First off, I must say that in terms of sound quality, the Globetraveler is in a different league due to its size relative to the Partner. No surprise - the bass presence is noticeably better on the Globetraveler. Another advantage it has is separate bass and treble controls, compared to the Partner's tone control.

In terms of FM performance, the sensitivity was only marginally better on the Globetraveler. In urban areas with telescopic antenna up, both radios suffered from overload. This resulted in distorted images of strong stations appearing in other places on the dial, interfering with weaker stations.

With the antenna up on the Globetraveler, it was noted that on certain shortwave bands there was some feedthrough of FM signals. I suspect this wouldn't be a problem once outside of town. Interestingly, the Globetraveler has a segmented antenna, giving about an extra foot if needed in fringe areas. Comparing the two radios on the 19m and 49m bands, it was hard to tell if there was a difference in sensitivity. The difference, of course is in the ease of tuning in stations with the Globetraveler's bandspread tuner. I also suspect (but have not verified) that the Globetraveler has better image rejection due to its more sophisticated tuner with separate front end tuning coils for each band.

The Partner holds up surprisingly well against the Globetraveler in terms of basic performance, but the Nordmende definitely is much more pleasurable to use and listen to.

Some other Globetraveler features to point out:
  • Sensitive tuning meter on all bands.
  • Inclusion of a Marine Band (1.5 to 3.5 MHz), although it's not used much for this purpose these days.
  • Long wave band, also useless in North America.
  • AM (BC) band, which uses an internal loopstick antenna.
  • External antenna connection, which helps shortwave performance significantly.
  • Operates from 5 "D" cells (7.5V).
The Globetraveler II is definitely the flagship of my "kofferradio" fleet. Can't wait for warmer weather to take it outside and test it outside of the city.



Sunday, November 30, 2014

NORDMENDE TRANSITA DELUXE

Radio makers tended to use the same model names over several years, while making significant design changes along the way. This is no different from the auto industry. A Toyota Camry, for instance, evolves in looks and features throughout the years. This applies to the Transita, the Telefunken Partner which I recently reviewed and probably every other radio produced in this era.

The Deluxe version of the Transita shown here was introduced in the early 60s, and is based on a wooden case covered with leatherette. This particular model covers the AM (medium wave) band, shortwave from 49m to 25m (~6-12 MHz) plus FM. The rounded profile gives it a charming retro shape. Later German radios became more squared off.

External connections include a Motorola automotive-type external antenna socket on the right hand side, and 9 Volt DC power input and headphone jack on the left. I didn't have much luck forcing a Motorola plug into the socket, because the chassis seems to be misaligned with the case.

A 6-cell C-size battery pack attaches with two snap connectors. As can be seen from the photo below, the back cover can be conveniently separated from the radio by unplugging the telescopic antenna's banana plug.


In this post, I will compare (subjectively) the Transita Deluxe with the Telefunken Partner 500.

I complained about the sticky tuning mechanism on the Partner. The Transita feels lovely and smooth in comparison. Despite that, on shortwave and AM, the Partner comes out somewhat ahead. The sensitivity (again, not measured, but subjective) is lacking on the Transita, as I found myself cranking the volume to near maximum when trying to find stations. Once I found a strong station, another Transita shortcoming appeared: apparent lack of automatic gain control (AGC). Because of this, I found myself jockeying the volume control every time I tuned in stations of varying strength.


From a sound quality standpoint, the Transita definitely was clean and generally sweet. The Partner, however, once again had the edge by offering more presence at the bass end. As opposed to the continuous tone control on the Partner, the Transita uses a switch, which introduces a single heavy-handed treble rolloff preset when pressed. I suppose a simple lower value capacitor swap in the tone circuit would improve it, but currently this is one feature I can't ever see using. 
 
The comparison of FM performance, however, was a little less black and white. While the Partner had apparently better sensitivity, in a crowded urban FM spectrum, this proved a slight disadvantage. I found the Partner subject to intermodulation (IM) distortion, which means it was overloaded with too many strong signals. This results in stations appearing like images in multiple places on the dial, and generally with distorted audio. This is different from the 'images' you would get on shortwave, because the higher I.F. stage frequency of 10.7 MHz on the FM band is generally effective at rejecting images. Retracting the telescopic antenna somewhat helped act as a front end attenuator, but then weaker stations get lost. By default then, the Transita makes a better big-city FM radio (sound quality aside), but the Partner would excel in rural fringe areas.

Performance aside, the wooden case and the retro curves make the Transita Deluxe a nice decorative element for any home with mid-century décor. While radio performance improved in later years, the plastic-fantastic housings they evolved into didn't carry quite the charm that this radio has.