Did a small MV lamp 50W cause such difficulties at the start of production at NARVA in Berlin?

The probability is quite high.



NARVA HQLG 50W/S, produced in the fourth quarter of 1972 in Berlin-Friedrichshain, GDR

In the meantime I have asked several collectors which are the oldest lamps of exactly this design with the "long neck" in their collections.
So far, not a single lamp produced before 1972 has surfaced.

Hence the assumption that this lamp only existed "on paper" for almost three years, namely in magazines and catalogues.


Source: Der Elektro-Praktiker, 1969, Heft 7, Seite 225

In 1969 a new MV lamp 50W from NARVA is announced in the magazine "Der Elektro-Praktiker" with two variants:

- HQL 50W
- HQLG 50W

The HQL 50W lamp was the version with the orthophosphate phosphor. What is unusual is why the designation HQLS 50W was NOT used, which would have been the correct designation according to the NARVA nomenclature at the time.

The lamp HQLG 50W was the version with the phosphor fluorogermanate.

The report says about the technical parameters of this lamp:
Luminous flux: about 1700 lm
Average lifespan: around 6000 hours

This very imprecise information allows the assumption that these values were only estimated with prototypes that presumably existed.


Source: Der Elektro-Praktiker, 1969, Heft 9, Seite 293


Source: Der Elektro-Praktiker, 1969, Heft 9, Seite 294

No lamp of this type has been found by collectors from the years 1969 to 1971, lamps only really exist from 1972 onwards.


Source: NARVA Hochdruck-Entladungslampen 1970

The lamp is listed in the 1970 catalog without further reference.


Source: NARVA Licht- und Strahlungsquellen 1971, Seiten 16 und 17

The lamp is listed in the 1971 catalog with further information.

1) auf Anfrage = on request
2) in Vorbereitung (schrittweise Einführung der einzelnen Leistungstypen) = in preparation (gradual introduction of the individual service types)
3) Lieferung in Vorbereitung = Delivery in preparation

Als Typ HQLG 50/S mit angepaßtem Lichtstrom für innenbeleuchtete Verkehrszeichen, Lieferung in Vorbereitung.
=
As type HQLG 50/S with adjusted luminous flux for internally illuminated traffic signs, delivery in preparation.


Another reference to these lamps is from 1974.


Source: Der Elektro-Praktiker, 1974, Heft 1, Seite 17

A type NARVA HQLG 50W/S is specifically pointed out here, which should preferably be used for the interior lighting of traffic signs.
From here it is noticeable in the technical data that the luminous flux was again only given as an estimated value: around 900 lm

It would be very interesting to see which lamps NARVA HQL 50W other collectors still have from the years 1969 to 1971.
This post will be supplemented or corrected as new information becomes available.

Regards

Olav