Z Codes

The militaries use various Z codes these days too, but below is the Cable and Wireless Z code, some of them may be fun and appropriate to use even today in Amateur Radio CW. For example, this evening I was using a rig that jumps around 200Hz every now and then, jumping between two frequencies. That is not QRH (drift), that is ZJF. And what about local QRM man made noise? That is neither QRM (which is interference from other stations) nor QRN (which is natural e.g. static). It could be ZIM. Back in the day, ZIM did not generally emanate from homes, but from factories, industries and hospitals.

Z codes below are from this source.

Note: numbers 1…5 following a Z signal mean:
(1) very slight
(2) slight
(3) moderate
(4) severe
(5) extreme.

Code Advice Information or Answer Question
ZAC Advise (callsign of) frequency you are reading
ZAK Transmission interrupted at … hrs.
ZAL Alter your wavelength.
ZAN We can receive absolutely nothing.
ZAP Acknowledge, please.
ZAR Revert to automatic relay.
ZBB Make … copies of the following message.
ZBF Use large message formula for the following telegram.
ZBN Break and go ahead with new slip.
ZBR Break circuit, retuning.
ZBS Blurring signals,
(1) dots heavy
(2) dots light.
ZCA Circuit affected, make readable signals.
ZCB Circuit broken, signal unheard.
ZCC Collate code.
ZCD Your collation is different.
ZCF Check your center frequency, please.
ZCI Circuit interrupted. Running and available.
ZCK Check keying.
ZCL Transmit call letters intelligibly.
ZCO Your collation omitted.
ZCP Conditions poor, increase to maximum.
ZCR Using concentrator, make warning signals.
ZCS Cease sending.
ZCT Send code twice.
ZCW Are you in direct communications with…?
ZDC Diagnosing circuit faults, will advise.
ZDE Message … undelivered.
ZDF Frequency is drifting to degree indicated, 1…5.
ZDH Your dots are too heavy (long).
ZDL Your dots are too light (short).
ZDM Your dots missing.
ZDT Following transmitters running dual.
ZDV Your dots varying in length, please remedy.
ZED Experiencing drop-outs, 1…5.
ZEF We are experiencing fill-ins, 1…5.
ZEG We are experiencing garbles, 1…5.
ZFA Failing auto.
ZFB Signals are fading badly.
ZFC Check your FSK shift, please.
ZFD Depth of fading is as indicated, 1…5.
ZFK Revert to FSK.
ZFO Signals faded/fading out.
ZFQ Frequency shift of your signal is … Hz.
ZFR Rapidity of fading is as indicated, 1…5.
ZFS Signals are fading slightly.
ZGF … signals good for … wpm.
ZGP Please give priority.
ZGS Your signals are getting stronger.
ZGW Your signals are getting weaker.
ZHA How are conditions for auto reception?
ZHC How are your receiving conditions?
ZHM Harmonic radiation from transmitter …
ZHS Send high speed auto … wpm.
ZHY We are holding your …
ZIM Industrial or medical interference, 1…5
ZIP Increase power.
ZIR You have strong idle radiation.
ZIS Atmospheric interference, 1…5.
ZJF Frequency jumping to degree indicated, 1…5.
ZKI Set watch on … kHz (or MHz) …
(1) continuous;
(2) until further notice.
ZKO Revert to on/off keying.
ZKQ Say when ready to resume.
ZKW Keying weight is … percent.
ZLB Give long breaks, please.
ZLD We are getting long dash from you.
ZLL Distorted landline control signals.
ZLP Low (minimum) power.
ZLS We are suffering from lightning storm.
ZMG Magnetic activity.
ZMO Stand by a moment.
ZMP Mispunch or perforator failures.
ZMQ Stand by for …
ZMU Multipath making … mark bias.
ZNB No breaks, we send twice.
ZNC No communications with …
ZNG Receiving conditions no good for code.
ZNI No call letters (identification) heard.
ZNN All clear of traffic now.
ZNO Not on the air.
ZNR Not received.
ZNS Here is new slip.
ZOA Have checked … (call letters) OK.
ZOD Observing …, will transfer when better.
ZOH Traffic on hand.
ZOK We are receiving OK.
ZOL OK, on line.
ZOR Transmit only reversals.
ZPA Printer line feed not received.
ZPC Printer carriage return not received.
ZPE Punch everything.
ZPF Printer motor fast.
ZPO Send plain once.
ZPP Punch plain only.
ZPR Rerun slip at present running.
ZPS Printer motor slow.
ZPT Send plain twice.
ZRA Reverse auto tape.
ZRB Relayed signals bad, adjust receiver.
ZRC Can you receive code?
ZRK Reversed keying.
ZRL Rerun slip before new running.
ZRM Please remove modulation from …
ZRN Rough note.
ZRO Are you receiving OK?
ZRR Run reversals.
ZRS Rerun message number …
ZRT Revert to traffic.
ZRY Rerun test slip with RYs, please.
ZSF Send faster.
ZSH Static heavy here.
ZSI Please furnish signal intensity.
ZSM Microvolt input to receiver is …
ZSN Give SINPO report on …
ZSO Transmit slips once.
ZSR Your signal is strong and readable.
ZSS Send slower.
ZST Transmit slips twice.
ZSU Your signals are unreadable.
ZSV Your speed is varying.
ZTA Transmit by auto.
ZTF Send fast and twice.
ZTH Transmit by hand.
ZTI Transmission temporarily interrupted.
ZUA Conditions unsuitable for automatic recording.
ZUB We have been unable to break you.
ZUC Unable to comply, will do so at …
ZVB Varying bias.
ZVF Signals varying in frequency.
ZVP Send VVVs please.
ZVS Signals varying in intensity.
ZWC Wipers or clicks here.
ZWO Send words once.
ZWR Your signals weak but readable.
ZWS Wavelength (frequency) is swinging, 1…5.
ZWT Send words twice.
ZXA Adjust to receive speed … (fax)
ZXC Pix … conditionally accepted.
ZXD Send dashes, please. (fax)
ZXF You are floating fast. (fax)
ZXH Limits high, reduce … cycles. (fax)
ZXJ You are jumping out of phase. (fax)
ZXK Is your synchronizing correct? (fax)
ZXL Limits are low, increase … cycles. (fax)
ZXO Last run defaced due to … (fax)
ZXP Go ahead with Pix.
ZXS You are floating slow. (fax)
ZXV Your modulation is varying. (fax)
ZYA Cease traffic, send As on A channel. (multiplex)
ZYC Cycling on ARQ, errors stored your end. (multiplex)
ZYK Check your keying on channel … (multiplex)
ZYM Change from single printer to multiplex.
ZYN Make bias neutral. (multiplex)
ZYP Change from multiplex to single printer.
ZYR Please put … on MUX revolutions.
ZYS The speed of transmission is … What is your speed of transmission?
ZYT Check your thyratrons.
ZYX Revert to MUX frames … channels.
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