Philips 170A
PHILIPS
170A. This large and impressive a.c mains valve radio was made in 1945, and
was the first post - WW2 radio to be brought out by PHILIPS in the U.K.
It
employs long, medium, & shortwave bands, and is easy to service once removed
from cabinet, as it has chassis supports at one end.
The
problem with this receiver, is that the output transformer is sometimes found
to be o/c on it's primary winding. It is not easy to come about a replacement
either, as it has feedback windings to supply negative feedback for the audio
amplifier.Many years ago, RADIOSPARES did market a range of output transformers
for popular radios by different companies, which includes this model, so do
look out for them at radio rallies / expositions !
Another
symptom of this set, is that people switch the set on, install an external aerial,
and are faced with a silent radio ! Do check the slide switch on the back of
the set (marked RADIO / GRAM), which is often in the GRAM position (for amplifying
external record player input). Move the switch lever in the opposite direction
!!, I have had many queries on this set, and it is not apparently obvious about
the location of this changeover switch.
The
valve line-up of this set is :- EF39, ECH35, EF39, EBL31, EM34, & AZ31.
Check
the h.t feed resistor to the tuning indicator valve, EM34. It often goes high
in value, or o/c, causing the valve to be inoperative. It gives an impressive
display when functioning properly.
The
"sister" company of PHILIPS, MULLARD - also had a variation of the
170A in a wood cabinet, called the MAS 281.