MilSepc Communication Logo Military and
Commercial Radio Z-Codes.

ZAA
ZAB
ZAC
ZAC
ZAD/x
ZAE
ZAF
ZAH
ZAI
ZAJ
ZAL
ZAL
ZAN
ZAN
ZAO
ZAP
ZAP
ZAQ
ZAR
ZAS
ZAT
ZAV
ZAX
ZAY

ZBA
ZBD
ZBE
ZBG
ZBH
ZBI
ZBL
ZBM
ZBN
ZBN
ZBO
ZBP/x
ZBQ
ZBR
ZBR
ZBS/x
ZBT
ZBU
ZBV
ZBW
ZBY

ZCA
ZCB
ZCC
ZCD
ZCF
ZCI
ZCK
ZCL
ZCO
ZCP
ZCR
ZCS
ZCT
ZCW

ZDA
ZDB
ZDC
ZDE/x
ZDE
ZDF/x
ZDF
ZDG
ZDH
ZDL
ZDM
ZDM
ZDN
ZDQ
ZDS
ZDT
ZDT
ZDV
ZDV
ZDY

ZEC
ZED/x
ZEF/x
ZEG/x
ZEI
ZEK
ZEL
ZEN
ZEP
ZEU

ZFA
ZFA
ZFB
ZFB
ZFC
ZFD/x
ZFD
ZFF
ZFH/x
ZFI
ZFK
ZFO
ZFQ/x
ZFR/x
ZFR
ZFS

ZGB
ZGF
ZGF
ZGP
ZGS
ZGW

ZHA
ZHC
ZHM/x
ZHS
ZHY

ZIM/x
ZIP
ZIR
ZIS/x

ZJF/x

ZKA
ZKB
ZKD
ZKE
ZKF
ZKJ
ZKO
ZKQ
ZKS
ZKW

ZLB
ZLD
ZLL
ZLP
ZLS

ZMG
ZMO
ZMP
ZMQ
ZMU/x

ZNB
ZNB
ZNC
ZNC
ZND
ZNG
ZNI
ZNN
ZNO
ZNR
ZNS

ZOA
ZOC
ZOD
ZOD
ZOE
ZOF
ZOG
ZOH
ZOK
ZOK
ZOL
ZOM
ZOR
ZOU
ZOZ

ZPA
ZPA
ZPC
ZPC/x
ZPE
ZPF
ZPO
ZPP
ZPR
ZPS
ZPT

ZRA
ZRA
ZRB
ZRB
ZRC
ZRC
ZRE
ZRF
ZRK
ZRL
ZRM
ZRM
ZRN
ZRO
ZRR
ZRS
ZRT
ZRY

ZSF
ZSH
ZSI/x
ZSM/x
ZSN
ZSO
ZSR
ZSS
ZST
ZSU
ZSV

ZTA
ZTH
ZTI
ZUA
ZUA
ZUB
ZUC
ZUE
ZUG
ZUH
ZUJ

ZVB
ZVF
ZVP
ZVR
ZVS

ZWB
ZWC
ZWO
ZWR
ZWS/x
ZWT

ZXA
ZXC
ZXD
ZXF
ZXH
ZXJ
ZXK
ZXL
ZXO
ZXP
ZXS
ZXV

ZYA
ZYC
ZYK
ZYM
ZYN
ZYP
ZYR
ZYS
ZYT
ZYX/x

ZZF
ZZG
ZZH
You are not observing circuit discipline
Your speedkey improperly adjusted
Advise (Call sign of) frequency you are reading
Cease using speed key
Signal (1) Not understood (2) Not held
Unable to receive you try via ____
Reroute the circuit by patching
Unable to relay. We file
Run ____ (foxes, RY's, mk, etc.)
Have been unable to break you
Alter your wave-Length
Closing down due to ____
We can receive absolutely nothing
Transmit only msgs of above precedence ____
Can't understand voice. Use Telegraph
Acknowledge, please
Work ____ (simplex, duplex mux sb)
Last word received (sent) was ____
Revert to Automatic Relay
Rerun tapes run on ____ since ____
Punching tape for transmission
Send blind until advised
You are causing interference
Send on ____ (kcs). Will confirm later

Cause of delay is ____
Following was sent ____ (time)
Retransmit message ____ to ____
You are sending upper case
Make call before transmitting traffic
Listen for telephony
Do not use break-in
Put ____ (speed operator) this frequency
Break and go ahead with New slip
Your tape reversed
I have traffic
(1) Characters indistinct (2) Spacing bad
When & on what frequency was message received
Break circuit. Retuning
Shall I send by ____ (method)?
Blurring Signals (1) Dots heavy (2) Dots light
Count ____ as ____ groups
Report communication with ____
Answer on ____ mc
I shift (or ask ____) to ____ (kcs)
Pull Back your tape one Yard

Circuit Affected. Make readable signals
Circuit Broken. Signal unheard
Collate Code
Your collation is Different
Check your center frequency, please
Circuit Interrupted. Running & available
Check Keying
Transmit Call Letters intelligibly
Your Collation Omitted
Conditions Poor, increase to maximum
Using concentrator. Make warning signals
Cease Sending
Send Code Twice
Are you in direct communication with ____ ?

Hr. formal message, priority ____
Expedite reply to my ____
Diagnosing circuit faults, will advise
Message undelivered. (1)Will keep trying (2)Advise disposal (3)Canceling (4) Btr. ads.
Message ____ undelivered
Frequency is Drifting to degree indicated, 1-5
Message ____ received by addressee at ____ (time)
Accuracy of following doubtful
Your Dots are too Heavy (long)
Your Dots are too Light (short)
Your Dots Missing
This is a multiple-address message
Report disposal of message ____
Message ____ relayed to ____ at ____ by ____
Msg just transmitted erroneous. Correct version is ____
Following Transmitters running Dual
Don't Transmit exercise messages until advised
Your Dots Varying length please remedy
Private message received for ____ . Advise
No private messages until ordered

Have you received message ____?
Experiencing Drop-outs 1-5
We are Experiencing Fill-ins 1-5
We are Experiencing Garbles 1-5
Accuracy of heading doubtful
No answer required
This message is correction to ____
This message is classified
Parts marked ZEP coming later
Exercise (drill message)

Failing Auto
Message intercepted or copied blind
Signals are fading badly
Pass this message to ____
Check your FSK shift please
Depth of Fading is as indicated 1-5
This message is a suspected duplicate
Advise when message received by ____
Message for (1) Action (2) Info (3) Comment
Reply to message? There is no reply
Revert to FSK
Signals faded out
Frequency shift your signal is ____ cps
Rapidity of Fading is as indicated, 1-5
Cancel transmission ____
Signals are Fading Slightly

Send ____ (answer)
____ signals good for ____ wpm
Make call signs more distinctly
Please Give Priority
Your signals getting stronger
Your signals getting weaker

How are conditions for Auto reception?
How are your receiving conditions?
Harmonic radiation from transmitter
Send High Speed auto ____ wpm
We are Holding Your ____

Industrial or Medical interference 1-5
Increase Power
You have strong Idle Radiation
Atmospheric interference; 1-5

Frequency Jumping to degree indicated 1-5

Who is controlling station? or I am ____
Permission necessary before transmitting messages
Take control of net ____ or shall I ____
I (or ___ ) reports into circuit (net)
Station leaves net temporarily
Closing down (until ____ )
Revert to On/Off Keying
Say when ready to resume
What Stations Keeping watch on ____?
Keying weight is ____ (percent)

Give Long Breaks, please
We are getting Long Dash from you
Distorted Land Line control signals
Low (minimum) Power
We are suffering from lightning Storm

Magnetic activity
Stand by moment
MisPunch or perforator failure
Stand by for ____
Multipath making ____ mark bias

No Breaks we send twice
Authentication is ____
No communications with ____
All stations authenticate
You are misusing authenticator
Receiving conditions No Good for code
No call letters (identification) heard
All clear of traffic
Not On the air
Not Received
Here New Slip

Have checked ____ (call-letters) OK
Relay to your sub-stations
Observing ___ will transfer when better
Act as radio link between me and ____
Can you accept message? (or) Give me message
Relay this message
Transmit your message (give info.)
What traffic have you On Hand?
We are receiving ok
Relay this message via ____
OK. On Line
Mail delivery permissible
Transmit Only Reversals
Give instructions for routing traffic
Obtain retransmission of message ___

Printer line Advance not received
Your speech distorted
Printer Carriage-return not received
Signals fading 1-5
Punch Everything
Printer motor Fast
Send plain Once
Punch Plain only
Rerun slip at Present Running
Printer motor Slow
Send Plain Twice

Reverse Auto tape
My frequency OK? Your frequency is ____
Relayed signal bad, adjust receiver
Check your frequency on this circuit
Can you Receive Code?
Shall I, or tune your transmitter to ____
Hear you best on ____ (kcs)
Send tuning signals on present frequency
Reversed Keying
Rerun slip before one now running
Please remove modulation from ____
I receive ____ (usb, lsb, isb's)
Rough Note
Are you receiving ok?
Run Reversals
Rerun message No. ____
Revert to Traffic
Run test slip please

Send faster
Static heavy here
Please furnish Signal intensity
Microvolt input to receiver is ____
Give SINPO report on ____
Transmit Slips Once
Your signals strong & Readable
Send Slower
Transmit Slips Twice
Your signals are unreadable
Your Speed Varying

Transmit by Auto
Transmit by Hand
Transmission temporarily interrupted
Conditions Unsuitable for Automatic recording
Timing signal will be transmitted
We have been unable to break you
Unable to comply. Will do so at ____
Affirmative (yes)
Negative (no)
Unable to comply
Wait. Stand by

Varying Bias
Signals Varying in Frequency
Send V's Please
Pass at once to sub-stations
Signals Varying in intensity

Name of operator on watch
Wipers or Clicks here
Send words once
Your signals weak but readable
Wavelength (frequency) is Swinging 1-5
Send words twice

Adjust to receive speeds ____ (RADIOFAX)
Pix ____ Conditionally accepted (RADIOFAX)
Send Dashes please (RADIOFAX)
You are Floating Fast (RADIOFAX)
Limits High, reduce ____ cycles (RADIOFAX)
You are Jumping out of phase (RADIOFAX)
Is your synchronizing correct? (RADIOFAX)
Limits are Low increase ____ cycles (RADIOFAX)
Last run defaced due to ____ (RADIOFAX)
Go ahead with Pix (RADIOFAX)
You are floating Slow (RADIOFAX)
Your modulation is Varying (RADIOFAX)

Cease traffic send A's on A channel (MULTIPLEX)
Cycling on ARQ, errors stored your end (MULTIPLEX)
Check Your Keying on channel ____ (MULTIPLEX)
Change from single printer to Multiplex (MULTIPLEX)
Make bias Neutral (MULTIPLEX)
Change from multiplex to single Printer (MULTIPLEX)
Please put ____ on MUX revolutions (MULTIPLEX)
What is your speed of transmission?
Check Your Thyratrons (MULTIPLEX)
Revert to MUX frames ____ channels (MULTIPLEX)

Incorrect
You are correct
Try again


Updated: February 10, 1998

1998-2014, Richard Lacroix
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