Pin A Common GroundPin A is used as the common ground for audio and is typically the same as chassis ground. This applies for all audio applications that I know of.
Memory aid: All the grounds are on pin A.
Pin B Handset speakerPin B is used for the radio's audio output that is to drive a handset speaker.
Back when 1/4" phone plugs & jacks were used for headphones the jack could also be a switch so that an internal speaker would be disconnected by the mechanical action of inserting the 1/4" phone plug. That function is still needed with the U-229 family connectors but it's now done by sensing the resistance between pin-A (gnd) and pin-B (headphone). For example, with a DC resistance <10 K Ohms (PRC-126) or <3.3 K Ohms (PRC-68) the internal speaker is muted
PS. The problem with 1/4" jacks is that they allow sand and/or water to get inside the radio, not a good thing. Note the U-229 family are sealed to prevent that.Memory aid: The capital letter "B" when rotated 90 degrees clockwise looks very much like the schematic symbol for headphones which are on pin B.
Pin C Push To TalkPin C is the Push to Talk release to listen line. When grounded it puts the transmitter into transmit mode and when released into receive mode. Note that this can not be considered as either an input or output, but rather as a buss line. Any equipment connected to this line can assert (ground) it.
In radios that have a CW mode, like the PRC-70, PRC-138 and HarrisRF-5000 series you use the PTT line for CW keying. If the radio only supports SSB modes but not CW, like the PRC-104, you need to use pin E for keying CW since using the PTT line on a SSB mode does not turn on a carrier.
Memory aid: after you have accounted for pins A, B and D, pin C is the one that's left. Only 4 pins are used for the audio functions.
Pin D MikePin D is the microphone input to the radio. Dynamic mikes are used with the U-229 family whereas carbon mikes were the common military mike on earlier versions of the connector like the U-77 or 1/4" phone plug.
In simplex radio applications the Push To Talk (PTT) switch not only closed contacts to activate the transmit function of the radio the PTT also has contacts that disconnect the mike when released. This makes is harder to modify a radio so that it can be used to spy on it's operators. For example the H-250 handset.
In duplex telephone applications the mike and earphone are used at the same time so there is provision for a hot mike as well as a switched mike. For example the H-350 handset. The H-350 may also be used with some voice encryption equipment.
Memory aid: The capital letter "D" looks very much like the schematic symbol for a microphone which connects to pin D.
Pin E Not StandardizedFor classical audio applications pin E is not standardized. Different radios use it for different purposes. For example:
PRC-68 Family of Squad Radios uses pin E for "12 Volt" vehicle power input.
The HF manpack radios PRC-74 and PRC-104 use pin E for the CW key input, and it's also used for high speed CW like from a GRA-71. Note that the pin C PTT line can NOT be used for CW keying on a radio that supports SSB operation, since there would be no RF output.
The VRC-12 series Squad radios uses pin E as the loudspeaker line to drive the LS-454.
The PRC-25, PRC-77 AUDIO and the RT-246, RT-524 & R-442 RETRANS use pin E as the retrans PTT to key the other RT with the Mk-456 Retransmission Kit. (See Retransmission below)
Pin F Not StandardizedThis is the center pin that is not present on a true U-229 connector. Many radios install the 6 pin version of this connector, yet do not connect a wire to pin F. Maybe it's done to allow a future modification, or maybe just to standardize the connector? Some equipment does use this pin where the other pins are used in the above audio functions, for example:
The PRC-68 Family, except the PRC-68 and PRC-68A, use this pin for digital up and down loading of the channel frequency assignments and as the retransmission PTT output. This supports a retransmission cable and cloning cable that are different than the Mk-456.
Some modern radios use the center pin F as a source of DC power for things like speaker mikes. If you have one of these radios would you tell me the open circuit voltage on pin F and the voltage when a load of 470 Ohms is applied to pin A (Ground)?
This is the connector that's now used for filling the crypto keys into all kinds of equipment. The SINCGARS AUDIO/FILL connector is probably the same as most U-229 family fill connectors. The CV-4228 PC to SINCGARS Fill Cable uses these pins. The SVM-68 (KYV-2) does NOT use this pin out, maybe because it was a first generation device that has serious security issues.
not used for SINCGARS fill na
Fill Request-Acknowledgment from Radio
(might be the PTT button on a hand set connected to the radio)
FILL REQ-N D
Fill Data into radio Data
FILL INFO E
Fill Clock into radio
(probably in the 1 kHz to 4 kHz range, to match manually pulling a paper tape)
FILL INFO AVAILABLE
not used for SINCGARS fill na
DS-102 is a fill data protocol for red keys and specifies the logic levels to be used. The logic levels are 0 volts and -6 volts.
Note that the BA-1372 (now BA-5372) battery is "backwards", that's to say the the Tip is negative and the flat bottom is positive.
DS-101 is a newer fill data protocol for red keys and uses standard TTL level (RS-485) logic levels.
The format of the fill data is classified. Some ideas about it are:
First, a device that uses fill data needs to know if it has valid fill data. For example the SVM68 (KYV-2) secure voice module for the PRC-68 family radios will function when no key is loaded. This is a huge problem in that an enemy could just zeroize a KYV-2 and the operator would think they were crypto covered but were not. One way to accomplish this is to use odd byte parity (Wiki: DES) this way an all ones or all zeros data set would violate the parity.
Second, a device that uses fill data needs to know that there was not a data glitch during the fill operation. Serial ASCII data (for example RS-232) has provision for parity bits so that each byte can be tested for validity. In addition blocks made up of some number of bytes can have a check byte added that not only detects some number of errors it can also correct a smaller number of them. This is called cyclic redundancy check (Wiki: CRC)
Third, a device that uses fill data needs to know that the key is intended for it and not some other cryptographic equipment. For example the key used for a GPS receiver (DAGR, PLGR) should not also work to key a voice encryption box (KY-57). There are a number of ways this might be accomplished. The design of the CRC could be different. One or more of the data blocks might contain a registration key that's specific to the device, etc. It's important that this be a very robust CRC for applications where Over The Air Rekeying (Wiki: OTAR) is used and bits are commonly lost or garbled. Also see (Wiki: DES)
Forth, every bit that's used for CRC or device specific ID is a bit not used as a key variable. The size of the key variable determines the difficulty of a brute force attack. DES uses 7 bytes (7 * 8 = 56 bits of key and 1 byte (8 bits of CRC) for a total of 8 bytes per block (64 bits).
Fifth, to minimize the amount of key material the same key is used for encryption as for decryption (Wiki: Symmetric-key algorithm).
||Data Rate Selector
rate < 16000
||baud rate < 16000||n.c.
|asynchronous Digital Data2||any
|synchronous Digital Data||baud
old style with flat
new style with hump
NAME: ITEM NAME O-RINGThis has been reported as being a metric 1.5 mm by 15.5 mm OD Chloroprene (generic Neoprene).
ADVN: CROSS-SECTIONAL HEIGHT 0.055 INCHES MINIMUM AND 0.061 INCHES MAXIMUM
ADYT: CENTER HOLE DIAMETER 0.605 INCHES MINIMUM AND 0.615 INCHES MAXIMUM
MATT: MATERIAL RUBBER CHLOROPRENE CLASS CR
|1.5 mm = 0.059055"||15.5 mm = 0.610236|