Jump to content

Samos


hcs

Recommended Posts

  A few days ago I picked up this Samos FuMB 4, it was used in western part of Denmark.

I need to restore some of the changes that was made of one of the previous owners.

Unfortunately, he made some holes in the front, that I have to close and paint.

The fuseholders is missing, but I have two spares, that I'll use for it.

The banana sockets missing, will be rebuilt with some used ones, I'll modify for correct looks.

I need to find another main switch, that fits the original hole in the front.

Some of the capacitors has been replaced, but I'll have to replace them by correct values.

 

IMG_7902.thumb.jpg.a3d6775ecd4b1df5c1757f0b874367e0.jpg

IMG_7898.thumb.jpg.338078db2f9977e11366fcfd64d6c29e.jpg

IMG_7904.thumb.jpg.dcfd6ad9edc4ff6a2848c0d0fdf9c3d0.jpg

IMG_7903.thumb.jpg.f48d33ac3f683b70014c8bd896b0a7b5.jpg

IMG_7905.thumb.jpg.850af1388d07216ee149bdc6f9147080.jpg

IMG_7911.thumb.jpg.c331f0a853be3a3f41caaab4ad4a799e.jpg

Edited by hcs
  • Like 1
Link to comment
Share on other sites

Powersuply has been repaired, I can't find the two 5uF capacitors in correct physical size and style, so I had to make a tradeoff and construct a plate of pertinax to mount the capasitors. I replaced the capasitors for axial types and the correct values.

Power before:

 

IMG_7917.thumb.jpg.eb3032c897aa938432bfc38a1ce07fab.jpg

IMG_7916.thumb.jpg.7f27264cb1eff1d43e1696d1ccdf3da6.jpg

 

After:

IMG_7973.thumb.jpg.f9ed032f6c0f5f1e787aa0e5d1fcdd0c.jpgIMG_7974.thumb.jpg.eacd910cf298ba278da1ef707ea1c292.jpg

 

Next step:

Replacing the capasitors in the LF amplifier, for the correct values and construct the missing part of the cabinet, for it.

IMG_7912.thumb.jpg.3a63fd336d923c85e222908af59f82b5.jpg

  • Like 1
  • Upvote 1
Link to comment
Share on other sites

Some progress...

The fuseholders is now in place and the modified banana sockets has been mounted, I made a fitting for the existing power switch, since I don't have the correct one.

I cleaned the front with water and soap.

In the NF block, all non correct capasitors has now been replaced.

  

IMG_8037.thumb.jpg.b9be0358338190a257a5ee716129caac.jpg

 

Banana sockets, Left original.

IMG_8032.thumb.jpg.42296b002b3cc404db64106018241f23.jpg

 

NF block.

IMG_8035.thumb.jpg.d1af4793ce67775b5d89284f19b227bd.jpg

  • Like 1
Link to comment
Share on other sites

  • 4 weeks later...

Some progress...

The holes in the front is now closed using chemical metal, still need som fine filling and finish, before painting.

6972E8EA-AC92-49FC-B53F-415312BA3F64.thumb.jpeg.aa6cb9b1d2885a3b60b427bd099bde0a.jpeg

9747FEE0-6063-46D2-8D8B-80E73F384D2E.thumb.jpeg.f744cf5832bcdaccf46be81a553e37dd.jpeg

 

The missing cabinet has been constructed in cobber plate, need painting...

B77FD800-0585-444F-BA70-97B25B0687DD.thumb.jpeg.f44b9e0f43108fb5aaf7844393dc5b51.jpeg

60A7A319-E58D-415A-B17F-F203153588AA.thumb.jpeg.bd4fd43a37aa08f4cb00d533a31f550b.jpeg

 

Testing of the tubes, showing that one of the RD12Ta tubes was defective, so I had to buy a new one.

(This is test of the new one).

9CF8A23F-9C82-4A4D-82A8-56FA30329A72.thumb.jpeg.03c6a1e69a101246a3d4f22ee57972ba.jpeg


Finally I made the first power on without tubes, all measurements was okay, then tubes was installed and first test was performed, radio is working ok, frequency readout is spot on. AM is very fine, but FM is distorted, if modulation is to high. I need to check the limiter and FM demodulation stage...

96E36F41-2AF5-47ED-8176-5C0963AF580C.thumb.jpeg.c87ac83cf8b2f1b47759a45877d6ea74.jpeg

 

 

Edited by hcs
  • Like 1
Link to comment
Share on other sites

Small update, the cabinet for the nf circuit, was painted with RAL 7031 blaugrau.4CEF74C4-18AC-42BD-801F-6E123C97A68B.thumb.jpeg.f180385a4f2878e79a5a6d4d3ed1c4c1.jpeg

56360E36-9436-4FD0-BDF1-2E9E7CB1364D.thumb.jpeg.6ccf669f347078672296cbf6b7a13e0c.jpeg

Edited by hcs
  • Like 1
Link to comment
Share on other sites

Yesterday I painted the front, with a paint mixed in a paint shop, it is not perfect, but close, I guess 78 years of smoke and dirt added to the original color.

I really don't want to repaint the complete front, so this is how it looks like now: 

419895604_Frontfinal.thumb.jpg.02f573eb28793ff379d1c8d34365aaa0.jpg

 

I checked the sensitivity and both AM and FM, seems to fulfill the specification of 1 V output in 4000 ohm @ 0,3 V noise, with 12 uV input level at the antenna. I don't have any impedance correction for the antenna, my signal generator is 50 ohm and the Samos is 150 omh balanced, so some tolerance is to be accepted.

Regarding the distortion, with deviation higher than around 13 Khz, I checked the IF, limiter and demodulator circuits, all seems to be working okay and all components are within specifications, my conclusion is that the radio is working, as intended, since it was made for measuring and detecting, not for hifi broadcasting. 

  • Like 1
Link to comment
Share on other sites

The homemade BNC adapter, that I got together with the Samos. The tip from unbalanced BNC is connected to one of the balanced inputs of the Samos, the ground/shield of BNC is connected to the other balanced input and ground of Samos.


362E5352-6655-4FEE-8938-35A90143BC2E.thumb.jpeg.0be7ef9496a23a49e42a5d026445be8f.jpeg

  • Like 1
Link to comment
Share on other sites

  • 2 years later...

@hcs , in this forum you don't need to cover the Third Reich regime

symbols (like swastika etc) - feel free to post everything as much original

as you can. Thanks!

Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Register for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
×
×
  • Create New...