Monday, April 23, 2018

The Atalanta was an excellent general coverage HF receiver for maritme use. 
Unusually, these sets have a 110V (AC or DC) low tension which is applied to the 13 valve heaters in series via a varister. The varister limits the inrush current when switched on, but also results in a very long warm up time. The first time I turned it on, I thought it was not working. After, something over 5 minutes it came to life! 
The HT is also 110VDC. Both HT and LT supplies would have been derived from the ship's 110 or 220VDC supplies, or via an inverter from the ships 24V batteries. This one has been modified with a small autotransformer to run off UK 240VAC mains. Unfortunately the HT is at nearly 150VDC - about 40% too high.
Apart from the HT it suffered from the usual leaky capacitors - most of which have now been replaced.
It works after a fashion, there are numerous hetrodynes indicating that the rather complex frequency changer sections need re-alignment. It is prone to motor-boating which may be related to the excessive HT voltage.
It is a job that will be addressed in due course.