Have my Siemens E311E receiver running again

[PA0NVD]

After a long and very abusing trip in a container for more than 6 month, being abused by the CR customs, exposed to high temperatures and humidity, I have my Siemens E311 running again.
The only thing that I noticed after all that abuse was that an electrolytic capacitor arced a few time with a loud click. and the receiver worked directly again. Quite amazing.
And again I am impressed with the reception. The receiver is a triple conversion. RF section 3 tuned LC filters with 2 EF93 RF amplifiers, first IF  broad band 1,3 - 1,4 MHz using a complex LC filter with 6 LC circuits, a second IF at 340 KHz with an 6 LC circuit bandpass filter and the third IF at 30 kHz.
The third IF filtering can be selected to +/- 150 Hz, +/- 500 Hz, +/- 1.5 kHz or +/- 2.5 kHz. or SSB using a complex filter with 7 LC circuits. . These are all LC filters and are build with 4 to 7 LC circuits to get a very nice BW. And that at 30 kHz!!
I really notice the nice sound quality compared to crystal filtered receivers. And also due to the E88CC balanced AF amplifier AM reception is nice and clear
All these filters result in an attenuation of 43 dB when detuned 1 kHz at the 300 Hz BW and 43 dB when detuned 5,9 kHz at the 5 kHz BW
SSB bandwidth is 3.5 kHz with a sideband suppression better than 60 dB
Frequency setting better than 100 Hz, stability (after warm-up) better than 20 Hz /24 Hours.
The reception is from 1.5 MHz to 30 MHz divided in 5 bands. You can tune rapidly using a free running oscillator or locked every 100 kHz and tune with the fine kHz tuning.
The receiver has 17 tubes, most of them E88CC
Amazing machine, and I am really enjoying it. It is one of those boat anchors I never will let go

[WA2SQQ]

Sounds interesting - photos?

[KK4YY]

Nico,

The E88CC valve, also known as a 6922 or 6DJ8 tube, is a very nice little dual triode, frame grid tube. Some examples are highly coveted and command very high prices. I bet your receiver does sound nice! I've attached a schematic of the E311 audio chain here, for those who may find it interesting — I do.

Don

[PA0NVD]

Fortunately, I have quite a few spare E88CC's
Now the hard part comes, trying to clean the guts. The receiver is plain dirty insid,. not inside the modules, but the outside.
Attached also the second IF and the 30 kHz third IF. It is quite clear that a LOT off effort has been put in filtering. My scanner died, so it is a photo. Repairing scanners and printers in Costa Rica is close to impossible and new ones are very expensive.
I have the manual of the E311, so if someone wants to see details, I will make a pic and post.

[KK4YY]

I've never seen an E311 before. There aren't that many European boat anchors in the USA. We tend to be a bit too provincial here.

The E311 manual is also online here:
https://bama.edebris.com/download/siemens/e311/plaene/E311_Plaene.pdf

[PA0NVD]

The receiver is also quite rare in Europe Don. Someone gave it to me because it was broke and he considered it too big and heavy.
And, due to the module structure, it is quite difficult to repair. You can not test a module outside the receiver when you don't have a test bench for it, or you should connect it to power supplies and a bunch of test equipment.
Lucky me. The 100 kHz vacuum crystal (the overall frequency reference) in the oven was bad, but I had one.