saba: UA-345 (UA345-X);

Hello RMO members,

As Herr Knoll mentioned in the 2nd posting above, it seems as though I was most fortunate to win on ebaY one of the dwarf-sized export models, SN 54/832516, and have discovered the intermittent to weak reception on the SWII and SWI bands are probably related to the failed small antenna coil on the terminal board at the rear chassis.

I have had to unwind one of the 2 sections wound on the sub-miniature coil.

I beileve it may be near impossible to find another "parts chassis" for this radio. Therefore, I respectfully ask for assistance to determine the wire gauge (or size in fractional millimeters) to rewind the lost wire.

I removed 96 inches of the wire, but it had several serious kinks and will need to be "re-wound".

I am aware of the 22, 26, and 30 gauge spools for winding coils. 

I also have not seen any reference to the ratings for the antenna coil on the schematic.

I would be most grateful if some member is aware of this issue.

Respectfully,

Robert Sarbell

 

Attachments:

• Antenna coil (102 KB)

To thank the Author because you find the post helpful or well done.

 

Hello Robert

I hope this is the coil. I took it out from my Saba to measure the wires for you.

The wires were fragile so they've  broken melted in wax, but I got them out from that mass to measure them.

The wires were 0.04mm diameter but my measure device is a digital caliper 0.02mm accuracy.....

so I've to measure them again (this week, I promise) with a micrometer.

Meanwhile I send you my Best Regards

Respectfully

Mário Coelho

 

To thank the Author because you find the post helpful or well done.

Hello Mario,

 

Thank you so very much for the wire dimensions in the millimeter size.  I believed it had to be EXTREMELY fine in gauge.

I am still puzzled to know if there are 2 pairs of wires on your antenna coil. I have what appears to be 2 small sets of windings, however there were only 2 wire ends.

It appeared that one of my wires came out from the aft top side (antenna in) and connected to the small 60pF capacitor; and the other wire came out from the forward portion and originally connected to the Ground/5000pF capacitor

I also followed very closely the postings between you and Hans Knoll. If Hans is monitoriing our communications I would gratefully request to know what that the specific rating should be for that coil??

I would be interested to know if the coil should have the full range of frequencies to include both SWi and SWII bands - i.e. from 11.3 meters through 90 meters; and also from 220 to 550 meters for the MW band.

Ii have seen in my JW Miller coils catalog an Antenna coil which covers the 11 meters to 550meters - that is a very wide spectrum!!

Respectfully,

Robert

 

To thank the Author because you find the post helpful or well done.

 

To thank the Author because you find the post helpful or well done.

 

Only two wires are visible outside the coil. In schematic only two are connected too.

 

The position in the aft, between 60pF (A) and schassis (B).

Respectfully

Mário Coelho

 

To thank the Author because you find the post helpful or well done.

Hello Mario,

We are in complete agreement - I will admit that I need to become fully qualified to insert my edited photos into the text as most of the members do. I attach here the first attempt to locate the broken end after removing the little coil. . .

 

The photo above was taken shortly after removal to determine where the broken end of the wire was located. The total length of unwrap on this coil bobinette was approx 94 inches. . . .

I measured the Litze wires on my small coil this afternoon, and took 3 separate readings. They were all 0.11mm. I honestly did not know what the size would be.

However, I believe that with the information provided by Hans, and yourself I should have no problems to repair that portion of the circuits.

I have not yet even performed the tube tests on the rimlocks or the UCL81 - so, that may be all I need. I am finishing the cosmetics on my Philips BX745A/60 motorized waveband selection receiver, so I should have this problem resolved shortly.

I do have a slightly audible 60hz hum, so the elkos may definitely need to be replaced

Many thanks to you and to Hans,

Respectfully,

Robert

 

Attachments:

• IF trap (85 KB)
• IF trap 2 (46 KB)

To thank the Author because you find the post helpful or well done.

 

Hello again

I already have mesured the wire, now with a micrometer 0,01mm accuracy. The diameter is 0,05mm.

I add here bellow one photo of my caliper when I have mesured 0,04mm, but as I said before ,it  has only 0,02mm accuracy.

Next week I intend to disassemble the coil from the plastic core for further information.

Respectfully

 

Mário

Attachments:

• caliper (7 KB)

To thank the Author because you find the post helpful or well done.

 

Hello again

I just have disassembled the coil core.

After removing the wax, 4 wires plus appeared.Surprise!! The coil is not made by a single wire, but it is formed by 3 wires twisted together. The cable is then divided and  winded up equaly by two twin spools.

.

After unrolling the cable I 've mesured 2,74 meters by each spool.

Conclusion:

This coil is made of a  +/- 5,48 m cable. The cable is made of three 3 twisted wires of +/- 0.04mm diameter. The cable was winded up in 2 spools, 2,74m per spool.

This is compatible with schematic where one can see only one coil.

3 wires of 0,04mm may be an alternative to a single cable of 0.11mm

I hope this observations can help You.

Respectfully

Mário Coelho

 

To thank the Author because you find the post helpful or well done.

Hello Mario,

Thank you so much for all of your efforts. While you disassembled your coil, I was re-winding my little  IF trap yesterday afternoon; and the length of one section was total of 102 inches (for 2.59 meters - almost the same as yours).

Then I took some time to slowly rewind the same size wires from some vintage hand-wound coils - I was using a Craftsman variable speed drill at a very slow rate to wind onto the outer section the 94 inches which were needed.

 

 

The item in the lower right corner, in the photo above, is a beeswax candle which I used to place a light coat of wax over the renewed Litz wire. And upon very enlarged views, I was able to determine that my .11mm wire was in fact 3 extremely fine strands as you precisely noted.  

The splicing of the ends (a very very tiny solder joint) was quite some feat. Then I simply placed the rewound cylinder onto the end of the ferrite rod.

The sleeve on which I rewound the new wire was cut from a very small thin vinyl hollow shaft which fit perfectly onto the little ferrite rod. And a few drops of the beeswax solved the "microsurgery".

I took several photos of the completed coil using my BK model 780 Precision LCR meter and the 3 inductance readings averaged to be 1126uH (from low 1125.4 to high of 1127.7uH.

One other point I must mention - thanks to Herr Knoll - on my model in the USA I will plan to replace the UY41 rectifier with the UY42. I have discovered (for the first time ever) the problem of "sputtering". It became quite apparent last night after nearly one hour of DXing on the SW bands.

The UY42 tube was designed for the mains voltage of 110V rms power.

There is a short article from the Philips tube makers about this "anomaly". . .

Respectfully,

Robert

PD: I would be most appreciative if any RMO member has a NOS NIB UY42 - I do know that Lorenz and Philips produced the tubes - perhaps Telefunken also.

 

To thank the Author because you find the post helpful or well done.