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Topic: another SO-A mast question RON 22-only |
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Higgins Fan
Advanced Member
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 Posted on: Apr 10, 2013 - 4:58am
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Two pictures of 305 I have not seen berfore. It also shows 305 as used in theater which is our mission during restoration. BTW, anyone know what the model and make of the IFF was?
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National WWII Museum
PT-305 Restoration
Phone: 504-528-1944 Extension 375
http://www.nationalww2museum.org/see-hear/collections/artifacts/pt-305.html
Fb: PT-305 "USS Sudden Jerk"
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Bob
MASTER
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Posted on: Apr 15, 2013 - 6:14am
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I am trying to learn more about the IFF. Ted you stated that the BN antenna was on one side and the IFF was on the other. Arent both of the dipole (ski pole) antennas for the IFF? The BN is for transmitting and the BK for recieving? I have drawings showing the IFF unit mounted on the back of the charthouse, starboard side for the 305. This is completely seperate from the radar which is on the port side. We have not been able to find a model number for this IFF. Anyone out there know about IFF's?
Bob |
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Jerry Gilmartin |
TOP BOSS
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Posted on: Apr 15, 2013 - 9:53am
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Bob and Fan,
I have been doing a lot of research on this exact subject for the PT658. All of this stuff is components of the WW2 Vintage Mark III IFF Equipment. This same stuff was used by the British, and the US Army (mostly in aircraft). The naming of the identical components is different for each country/service in order to confuse the enemy. The US Navy calls it one name, while the US Army calls the same item by another name, while the British named it something else as well. With the help of several people, I have obtained an authentic IFF "Ski Pole" antenna for the BN Unit and then we copied it to make another similar "Ski Pole" antenna for the ABK. So we will have a "fat" one and a "skinny" one. Also, in April 2012 I visited Don Shannon at Fall River Battleship Cove and saw that Don already has most of the same components and parts he needs for installing a complete IFF suite on the two boats there. While on the PT617 with Don I took measured photos of one of Don's IFF antennas so we could use it as a starting point to make our copy.
Moving to the individual components of the IFF recievers, for both the BN Unit and the ABK, they were both made under govt contract by several different companies, The make and models are similar. They are called the "BN Unit Interogator- Responsor" made mainly by Farnworth among several other manufactures. The "BN Unit" also needs to be connected to the PPI Console (Scope of the Radar) via a "Duplexer Unit".
The "BK" (or ABK) is properly called a "Transmitter-Reciever (Transponder)" and it was made primarily by Hazeltine among others. It also has associated equipment namely a "Code Selector Switch" and a "Control Box" and a "Destructor Switch". The Destructor Switch triggers a small Thermite Charge which destroys the two main "Top Secret" vacuum tubes inside the guts of the BK Unit. The Thermite Charge is about the same size as a 12 gage shotgun shell. I have been slowly collecting all these parts together over the last few years and have almost finished. We still need to mount the two Ski Pole antennas this spring to the PT658. We will mount them one to the forward side of the Radar Mast and the other to the top of the charthouse on the starboard side, per the PT625 class drawings. I have a couple of technical manuals for the "ABK Transponder" and the "BN Unit" that I got from the HNSA webmaster Rich Pekelney. The USS Pampanito website was where I found out most of this info, since they used the same equipment on the WW2 submarines. The two books I have are electronic versions and I could possibly send you an electronic copy if you want me to.
Jerry PT658 Portland
Here are some pictures shows what I am talking about.
Newly mounted ABK and Control Box and Code Selector Switch inside Wardroom
Another view from the front
Schematic of ABK Connections
Photo of ABK connected with cables to accessories
ABK Unit outer case
IFF ABK upper case removed exposing sensitive vacuum tubes to be destroyed by thermite charge
IFF Destructor Switch
British IFF MarkIII with control box and code selector switch in front
Pampanito BN Unit
Jerry Gilmartin |
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Bob
MASTER
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Posted on: Apr 19, 2013 - 6:34pm
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Jerry,
Good info. Thanks.
Bob
Bob |
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