Restoration of the Breting 40 Receiver

Breting 40 Receiver Restoration


Author: Edgardo Castro Bruse
Author: YS1ECB
AUGUSTO EDGARDO CASTRO BRUSE
Calle Loma Linda
Residencial Loma Linda casa No. 4
Col. San Benito.
San Salvador. El Salvador.

San Salvador , January 17, 2014



Introduction
Breting 40 Receiver This interesting receiver was bought by a friend of mine, and while tracing its where about, it turned out to belong to a ham radio pioneer Eng. Miguel Angel Sol, YS1MS. In view of this I put a lot of time, effort and work to repair this radio to honor YS1MS and to provide my friend Mr. Salvador Galdamez, and the radio enthusiasts with information on a restored and working Breting 40 receiver.
This is a unique radio in several aspects. Since not very many were produced in the Breting Factory, at Los Angeles, California. I think it may be the only one in El Salvador and perhaps in Central America.

Breting 40 Receiver restoration Breting 40 Receiver chassis Breting 40 Receiver parts Breting 40 chassis


Radio before Restoration
The chassis was carefully cleaned by the owner who took a few pictures. Later I took many more pictures in order to help the viewer identify the complete wiring, and some particular areas that are of interest to any one attempting to repair the Breting 40 receiver. Please click on images to enlarge.


Receiver before restoration Breting 40 before restoration old receiver before restoration Breting 40 before parts replacing old receiver before parts replacing
old radio: before parts replacing Breting 40 inside view Breting 40 components before Receiver components before replacing old receiver connections view


Radio after Restoration
All paper condensers were measured for leakage, and all but one had a leakage greater than 80 microamperes, therefore all were replaced. All mica condensers were left in place and all resistors that had a change in value greater than about 35% were replaced. The original wiring of the Breting 40 is unique in that, all leads are only inserted at the connection point, and not bent and tighten as in any other brand of radio. This makes the replacement of any resistance or condenser a lot easier. To see the new wiring, please click on images to enlarge.

Receiver after restoration Breting 40 after restoration old receiver after restoration Breting 40 after parts replacing old receiver after parts replacing
old radio: after parts replacing Breting 40 inside view Breting 40 components after Receiver components after replacing old receiver connections view


Receiver's Circuit Diagram & Alignment Procedure

Description of the Circuit
The circuit diagram for the Breting 40 receiver is practically non-existing. Therefore a partial circuit had to be reconstructed by combining information obtained directly from the chassis, with the available information for the Breting 9, 12, and 14 models. I concluded that about 85% or more of the Breting 40 ia a combination of models 9 and 12. Models 9 and 40 have a very curious inter-stage audio amplifier that seems to provide and additional way to control the receiver's volume. This can be seen by observing the 6K7 driving the 6F6 in the model 9 diagram. A complete diagram of the audio amplifier was reconstructed. It is shown in the two handmade diagrams. Please click on images to enlarge.

Breting 9 Receiver schematic Breting 12 Receiver schematic complete diagram of the audio amplifier Breting 40 diagram of the audio preamplifier


The RF, MIXER, IF,BFO and DETECTOR circuits are basically the same as in the Breting 12 receiver. Except for the type of tubes. Diagrams of models 9 and 12 are also included for comparison and information. Note: I could not find out what was the use of the 6C5 in the Breting 40 receiver.

Alignment Procedure
The alignment was performed with an RCA RF generator the Viz-WR-50C, and a frequency meter from Optoelectronics.

IF Alignment
The intermediate frequency of this receiver is 432 KHz. As a first try I followed a standard procedure, and adjusted the IF transformers to Maximum S meter reading. This resulted in a too sharp selectivity and too much microphonism and a "hollow sounding radio".
Breting 40: the trimmers on the IF transformers can be seen in fig 1 So, I made the following changes:
  1. The crystal filter was disabled by placing the Crystal Filter Control to its most counter clock position.
  2. I placed the RF generator hot lead next to the control grid wire of the 6J7 mixer. Use masking tape to keep both wires together. See fig 1.
  3. The left trimmer of each IF transformer was adjusted for Maximum S meter reading with the RF generator at 430 KHz. With a bit of 400 cycles modulation.
  4. The right trimmer of each IF transformer was adjusted for Maximum S meter reading with the RF generator at 434 KHz. With a bit of 400 cycles modulation.
This procedure permits a band width of about 4 to 6 KHz. a very good selectivity, and gets rid of the microphonic sounds. The 6J7 control grid wire, and the trimmers on the IF transformers can be seen in fig 1. Please click on image to enlarge.

Breting 40: Alignment & Conclusion

Oscillator Alignment
First locate the trimmers and padders by looking at Figs 2, 3, 5 and 4 respectively. Please clik on images to enlarge.

Breting 40 Receiver Alignment, Fig.2


Breting 40 Receiver Alignment, Fig.3Breting 40 Receiver Alignment, Fig.5


Calibration Procedure for Oscillator
Band RF Generator Dial's reading Adjust...
1 1400 KHz. mod 1400 KHz Trimmer to 1400 KHz
  600 KHz. mod 600 KHz Padder to 600 KHz
2 3 MHz. mod 3 MHz Trimmer to 3 MHz
  2 MHz mod 2 MHz Padder to 2 MHz
3 6 MHz. mod 6 MHz Trimmer to 6 MHz
  4 MHz. mod 4 MHz Padder to 4 MHz
4 14 MHz. mod 14 MHz Trimmer to 14 MHz
  8 MHz. mod 8 MHz Padder to 8 MHz
5 28 MHz. mod 28 MHz Trimmer to 28 MHz
NO PADDER ADJUSTMENT IN BAND 5


Antenna and RF stage Alignment
First refer to Fig.4 to locate the appropriate trimmers. The strip of trimmers, closest to the front apron of the chassis, is the Antenna deck.
The next strip of trimmers is the RF deck.

Breting 40 Receiver Alignment, Fig.4


Set the RF generator to the frequency shown in the chart for each band. Connect a piece of wire to the antenna terminal of the radio to act as an antenna. Place the RF generator about 2 meters away from the radio. Adjust its output to get an S-6 reading on the radio S meter.
Adjust the Antenna and RF stage trimmers for Maximum S meter reading.

Calibration Procedure for Antenna & RF Stages
Band RF Generator Dial reading Adjust...
1 1400 KHz. mod 1400 KHz For Max. S meter reading
2 3 MHz. mod 3 MHz For Max. S meter reading
3 6 MHz. mod 6 MHz For Max. S meter reading
4 14 MHz. mod 14 MHz For Max. S meter reading
5 28 MHz. mod 28 MHz For Max. S meter reading


Conclusion
The Breting 40 was a radio designed for ham operators and commercial companies that wanted to have point to point communication.
Some unique features
  1. You can use the radio's amplifier as a driver to a high power AM transmitter by selecting this function from a front panel switch.
  2. The entire wiring is designed to easy any future repairs. The leads of resistances and condensers are just joined and soldered, without bending and tightening them to connection lugs.


General features
  1. The IF transformers produced a very sharp selectivity, to the point that I had to calibrate their trimmers about 2 KHz above and below the 232 KHz. Crystal frequency.
  2. The sensitivity is very good except in band 5. Also, since there is no padder trimmer for this band, the dial calibration is not very good.
  3. The large toothed wheel produces a very pleasant and smooth tuning without back slash.


AKNOLEDGMENT
I would like to thank my friend, Mr. Salvador Galdamez for trusting me the repair of his unique receiver and for being extremely cooperative in the buying of the necessary parts to accomplish this job, as well as for being very supportive during the entire process.



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