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| CSR-5Y owned by WF2U. (Photo by Meir, WF2U) |
CSR-5Y and Diversity Reception
The Marconi CSR-5Y, a variant of the CSR-5, was altered for diversity reception. Rather than having a toggle switch for the AVC, a three position rotary switch is used. It is marked AVC - OFF - SINGLE. The Send/Rcv switch is eliminated since the receiver is intended to be in receive mode all the time. There is a screw-on microphone type chassis connector fopr the AVC line.
The AVC was probably derived from an external comparator when in Diversity mode. In all other respects, the ' Y' variant is identical to its more common cousin. The CSR5Y would mostly likely be found in a shore installation.
SPECIFICATIONS
Basically the CSR-5Y is the same as the CSR-5 series found elsewhere in the web page. The CSR-5Y has the 2 screw terminal audio tap, dual ganged shaft crystal filter and restamped 6SG7 labels for V2 and V4.
From the nameplate:
CSR5Y #105-865 Serial 112
Pat'd 1927-44
Spec 105-927
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| CSR-5Y owned by WF2U. (Photo by Meir, WF2U) |
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| During WWII, most Marconi CSR5's saw service in shore installations. They could be used for single receiver reception (Model CSR5 or 5A) or in diversity mode using the Model CSR-5Y .This rare, but low-res photo illustrates three CSR-5Y receivers in a triple diversity configuration. (Photo source unknown) |
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| Top and rear view of chassis with cover in place. Since CSR5Y's were mainly rack mounted, Marconi made a custom cover for the unit. (Photo by Meir, WF2U) |
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| Rear of chassis. (Photo by Meir, WF2U) |
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| Closeup view of power and signal connectors. (Photo by Meir, WF2U) |
CSR-5Y VERSUS CSR-5 DIFFERENCESFrom the exterior, there are two differences between the CSR-5Y and the CSR5 models
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| On the CSR-5Y, the AVC On/Off and the SEND/RCV toggle switches have been removed. The resultant holes have been covered by a rectangular plate. A three position switch was installed with the marling of AVC,/OFF/SINGLE |
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| At the rear, the major difference is the fitting of a microphone style connector below the photo jacks. |
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| This CSR5-Y (artifact
# 1979.0677.001) held in the collection of the Science and Technology Museum
has a different marking where the AVC switch used to be A three position
switch is marked DIV-OFF-INT. The crystal oscillator switch appears
to be labeled DIV – M.O. The AC power switch is labeled STANDBY (in
the lower position the switch is labeled OFF on a standard CSR-5).
There is something else to note, There is Dymotape labelling on the front panel. so we cant be sure what the factory issue panel originally read. (S&T photo) |
Radio collector Tom Brent summarizes as to what is known about the CSR-5Y receiver as of January 1/23."We know the following to be true:
1. The Canadian Army ordered a YG-11 diversity receiver in June 1944.
2. Canadian Marconi built at least one type of diversity system that utilized multiple CSR-5Y receivers.
3. Canadian Marconi built at least three examples of their Type 105-930 common oscillator which appears to be part of a diversity receiving system. At least one of these oscillators was used by the COTC station in Quebec.Based on the points above, the following statements can be made:
1. We have no evidence that establishes which Marconi firm (Canadian or British) made the YG-11 system.
2. We do not know what receiver was used in the YG-11 system.
3. We do not know if the 105-930 common oscillator was used in the YG-11 system.
4. We do not know if the 105-930 common oscillator was used with the CSR-5Y receiver"This CSR-5Y schematic shows what modifications had to be made to a CSR-5 receiver in order to make it work as a diversity reception receiver, Schematic provided by Tom Brent,. The source document originated from the Canada Science and Technology Museum in Ottawa.
This schematic sheds light on some parts of the CSR-5Y. The former crystal oscillator switch is now labeled DIV-XTAL-MO and in the first position, regulated 150V is removed from the 9002 oscillator plate and an external signal is fed in via a new concentric connector. In the XTAL and MO positions, any signal on that connector is grounded and the receiver operates in the regular CSR-5 manner. The new 3-position AVC switch is labeled DIV-OFF-INT and this requires the addition of 3 new terminals for AVC connections to rest of the diversity system. The lone connector we see on the back of a CSR-5Y is possibly for signal input from an external frequency control such as the Canadian Marconi 105-930 common oscillator.
Contributors and Credits:1) Meir Ben-Dror, WF2U <wf2u(at)ws19ops.com>
2) Tom Brent n avyradiocom(at)gmail.com
Mar 4/23