|Here is my E52b collection.
This is a very interesting radio.
This is advanced mechanical technology.
I work as a broadcast equipment designer,
and I have learned much by study E52b to get ideas in my products.
|1 ... E52b-1, Shack
|2 ... E52b-5, Serial nr. 1466, from
Trondheim, Black frequency microfilm.
This receiver is 100% OK and trimmed. Original paint. Variable BFO reinstalled.
|3 ... E52b-1, Serial nr. 1273, from
Variable BFO removed.
|4 ... E52b-1, Serial nr. 2242, from
This receiver is 100% OK and trimmed. Variable BFO removed.
|5 ... E52b-1, Serial nr. 734, Black
This receiver is 100% OK and trimmed. New paint, late war production without variable BFO
|6 ... E52b-7, Restaurert
Variable BFO reinstalled.
|Köln E52bb is the best short-wave receiver produced
The performance can be compared with the R390.
R390 is a famous US receiver from the 50s, 60's and 70's.
E52 is a super heterodyne receiver with an IF frequency on 1 MHz.
The MF filter is extremely good with a variable bandwidth from 200 Hz to 10 KHz and with a flat pass band.
Mirror frequency is < 1: 50000.
|This is a block diagram over Köln.
The HF amplifier have 5-gang tuned circuits.
The oscillator capacitor tuning capacitor is synchronised with the HF amplifier capacitors
in a 6-gang capacitor. This heavy filtering gives a very good rejection of unwanted signals.
Both mirror frequency and large signals on frequencies near the operating frequency.
The MF section is very advanced. It has 6 tuned circuits before the first amplifier.
Then the signal pas a XTAL filter, amplifier and a second XTAL filter.
The pass band of the XTAL filter can be selected from 200 Hz to 10 kHz with the pass band regulator.
Specifications for the E52 'Köln'
A1, A2, A3
110-230VAC 50-60Hz, or 12VDC
245mm x 446mm x 350mm
AM (wide) 3,5µV
CW (wide) 1µV
CW (narrow) 0,3µV
Better than 94dB @20MHz
Better than 100dB
XTAL - 1000,9kHz
or 995 kHz - 1005 kHz
continuously variable between 200 HZ - 10 kHz
better than 30 x 10 E-6 °C
E52b page 2