D:\WW2\seventh survey\War Diaries\7th Survey 1942\appedix

APPENDIX 'A' TO WAR DIARY OF 7^TH SOUND RANGING BTY. R.A. for FEBRUARY 1942

Subject : Report on Radio Link Trials held 20/21^st Feb. 1942

7SR/SR/5/18. SECRET

To O.C., 7^th Survey Regiment. R.A.

Reference my report No.7SR/SR/S/5/9, dated 18/8/41,and to the subsequent return of the faulty Radio Link on charge to this Battery to Ordnance for repair, this equipment was received back from Ordnance Workshops at Aldershot on 29^th Jan. 1942. In accordance with your instructions, on the receipt of this Radio Link in this Battery, the equipment was placed into stores pending the arrangement of the trials, During the time between its receipt and the above trials, no-one was allowed to touch it except for checking in of major components by B.Q.M.S. and Wireless Mechanic, and a D Troop Officer on taking over on the morning of the trial. The trials themselves were divided into three portions, as below : - (1) Drawing by D Troop from Battery stores,issue to H.Q.and detachments, and preliminary netting in Battery vehicle lines. This was all carried out in the presence of Capt. Barker, R.A.O.C., from Command Ordnance Wireless Shops, Aldershot. (2) Deployment and recording of guncotton bangs on a base near PEMBURY, on which "Q" Battery had been ordered to deploy during Corps Skeleton exercise GALAHAD. This base was considered a fair representation of normal conditions in close country. Deployment was scheduled to take place at about 1800hrs on the 20^th Feb. in order that the conduct of the equipment during hours of darkness, and particularly at about midnight, might be tested. (3) Deployment, and recording of guncotton bangs by day after such deployment as might be ordered during Regimental Exercise NUTS on 21/2/42, This was also part of a normal "Q" Battery exercise and represented a fair picture of day deployment in close country.

During part (2) of above, in addition to Capt. Barker, Major Prince, R.Sigs., and Mr. Roberts, both from C.I.E.S.S., Capt. Tanner from R.A. S of S., and Capt. Hague. 1^st Survey Regt. R.C.A., were present. During part (3), Major Prince and Mr. Roberts only were present.

Detailed methods used and results obtained are detailed below for each of the above sections: (1) Preliminary Netting. Some little time was taken after issue from stores in preliminary netting in wagon lines. This was due to a number of mechanical faults and wiring troubles. Two senders were put out of action owing to crossed leads in a connector which caused the fusing of the internal lead to the filaments. One or two minor mechanical faults were set right by the Troop Wireless Mechanic (D. R. Osborne). In this connection, Capt. Barker stated that normal R.A.O.C. workshop procedure was to test components on the bench and not complete installations, which latter was impracticable. These bench tests are designed for standard equipment, and, for example connectors apparently of a standard No. 11 Set pattern would be subjected to a standard test. It would appear an advantage therefore if connectors to R105's or Senders No. 1 differing from the standard No.11 Set connector in internal wiring only were so marked, thus avoiding the trouble typified in the case of the two Senders No.1 mentioned above. He also requested that all the Anode Converters be returned to Workshops for re-making in a mechanically stronger manner than could be done by Unit Wireless Mechanic with the tools at his disposal. /to page two,

Radio Link Trials (Page 2).

Other mechanical defects must have arisen since leaving Ordnance Workshops and must be attributed to transport. In this connection, both Major Prince and Capt. Barker were of the opinion that some fitting should be arranged in trucks for carrying of Radio Link and No.11 equipment.

(2) Night Deployment. Ref. Sheet 1" - 125. D Troop left Battery lines at about 1900 hrs., and deployed from Pembury Church at about 1930 hrs. on a base as follows: Frequency Sender No. 1 M1 106634 Range from HQ - 5000 yrds. 8465 M2 083630 " " " - 2500 yrds. 7570 M4 049631 " " " - 1500 yrds. 7680 M5 028637 " " " - 4000 yrds. 8130 AP1 083649 " " " - 3500 yrds. AP2 047654 " " " - 3500 yrds. HQ 061622 Speech Freq. 6955 M3 was not represented owing to the failure of the Senders No. 1 noted in Section 1. Total length of base - 8000yds. Type of country - close and broken up, one crest between H.Q. and M5, ground to the East of M3 decreasing in height. Weather - Cold (very) and dry. First transmissions from H.Q. was at 2015 hrs. All stations netted well on speech except M5 which was brought in later by increasing the aerial to 15', although by the time that M5 was got in, general interference on speech frequency was extremely bad. At 2200 hrs, M1, M2 and M4 were in action and a Bangs Party left for Hostile Battery areas. Guncotton Bangs were let off in series of three in positions representing enemy Field Batteries as follows : - Sheet 1" - 125, Series 1 - 092688 Series 2 - 045680 Series 3 - 045680

Results were as below: Series 1. 2212 hrs. Shot 1 - M1 Sending, but no break. M2 Nil. M4 Good Break. 2227 hrs Shot 2 - Recorder not working. 2242 hrs Shot 3 - M1 ) Sending but M2 ) no M4 ) breaks. Series 2. 2255 hrs Shot 1 - M1 Good break. M2 Morse interference. No readable break.. M4 Good break. 2259 hrs Shot 2 - As Shot 1. 2301 hrs Shot 3 - As Shot 1. Series 3. Shot 1 - M1 Did not record. Did not hear AP owing to bad speech conditions M2 Fair break. M4 Not recorded. M5 Dis. Shot 2 - M1 Did not record. M2 Fair Break. M4 Good break. Shot 3 - As shot 2.

In regard to series 3, to preclude possibility of insufficient lead of AP's to allow sets to run up, Mic's were told to switch on and remain on for twenty minutes. Owing to extremely bad speech conditions, however, this order could not be got through to M1 in time. As regards M5, it was found after the shoot that the reason for no kicks being received was that an internal lead in the interconnection unit of this set was disconnected. This was connected before the following days trial. /to page three.

Radio Link Trials (Page 3).

At various times during this trial, tests were made by sending tone to ascertain if there were any drift, which established that drift on the Sender - R105 link was negligible. It should be noted that before netting on tone however, the R105 were switched on and run for five minutes.

(3) Day Deployment. Exercise NUTS. Ref Sheet 1" - 135. D Troop deployed under command a Medium Regt. On the following base : - M1 257413 Range from HQ - 5000 yrds. M2 257407 " " " - 5000 yrds. M3 216404 " " " - 2000 yrds. M4 197404 " " " - 5000 yrds. M5 178401 " " " - 4500 yrds. AP1 241433 " " " - 6000 yrds. AP2 184421 " " " - 5000 yrds. HQ 216383

Total length of base - 8000 metres. Type of country - very close and broken up. Weather - Cold and Dry. Snow later. Slight wind. M3 did not arrive on the ground till nearly at the conclusion of the exercise, being left with W/Mech. in Bty. Lines for repair.

At 1150 hrs, base was in action on 4 mic's as below : - M1 - Tone giving full scale deflection on R105 M2 - Tone giving 2/3 scale deflection on R105 M4 - Tone giving full scale deflection on R105 M5 - Tone giving 2/3 scale deflection on R105.

Bangs representing enemy guns were let off as follows :-

Time Map ref. Charge

1. 1220 hrs 198452 8 lb. 2. 1235 hrs " 8 lb. 3. 1238 hrs " 8 lb. 4. 1330 hrs 201465 8 lb. 5. 1335 hrs " 4 lb. 6. 1340 hrs " 12 lb. 7. 1402 hrs 235463 8 lb. 8. 1421 hrs 207486 8 lb. 9. 1444 hrs 178449 8 lb. 10 1602 hrs 198542 8 lb. 11 1610 hrs " 4 lb. 12. 1620 hrs " 14 lb.

Results were as follows: - Shot 1 - Not recorded. Wireless Drill. Shot 2 - M5 _ small kick but readable. M4 excellent M2 - small and doubtful. M1 - Readable but confused by ripple. Shot 3 - As 2. Shots 4 & 5 - not heard by AP's. (Pocket?). Shot 6 - M5. Small but readable . M4 excellent. M2 - out of action, aerial being increased. M1 - Good but confused by ripple. Shot 7 - Recorder trouble. Shot 8 - M5 readable. M4 good. M2 good. M1 Readable. Shot 9 - Recorder trouble. (Sticky control relay). Between shots 9 and 10, the senders No. 1 at Mic's 4 and 5 were changed over. Shots 10, 11, 12 - M5 Good. M4 Fair. M2 Readable. M1 Readable.

General Conclusions.(1) Transport. That properly fitted trucks are essential if the equipment is to be kept in good order. The Mechanical Defects which developed between Ordnance Workshops and Battery Stores indicated that unless adequate springing and securing is provided . even if good roads are available, good performance of the equipment will not be maintained. /to page 4.

Radio Link Trials (Page 4).

2. Anode Converters. That to ensure adequate robustness, anode converters should be fitted in Ordnance Workshops where equipment is available to make a sounder job than is possible within units. 3. Night Conditions. It is clearly shown that night conditions are extremely difficult, even with equipment in working order. Drift being now negligible, the addition of wavemeters to G1098 will enable some form of calibration other than relative, but the frequency allotment and discipline must still be carefully watched. It seems possible however that even by night , given practice, good results may be obtained. 4. Drift. It was definitely established that with properly adjusted sets, drift is negligible. In one case, M4, the tuning of the R105 was not touched from the close of the night trial to the start of operations on the 21^st, but tone was received perfectly without further adjustment of tuning. It is advisable however to run the R105 sets for from 5 to 15 minutes to warm up before netting. 5. Signal Strength. For satisfactory operation, a deflection on R105 meters of 1 m/a 'tone' is necessary. If this is not obtained, microphone aerials must be increased until it is obtained. Increase of reception strength appears to be a direct function of aerial length. (See Day Trials, M2, Shots 2 & 3, and Shot 8). 6. Aerials. Some compromise must be arrived at between considerations of concealment and the technical factors governing microphone position selection in woods and other screened places, and the Wireless Communication aspect of unscreened aerials. At Headquarters, and indeed, wherever sets are to be operated from trucks, the necessity for aerial bosses fitted to the vehicles such that aerials may be erected above the trucks, instead of in positions screened by them, is imperative. At present, without such fittings, the erection of an aerial in a position not screened by the truck involves using a longer aerial lead than is advisable, and signal strength is lost either by direct screening due to the necessity for the aerial (bosses in field section trucks) to be hard by the truck, or in the length of lead from the truck to the aerial in a less screened position. This may be taken care of in H.Q. vehicles by the proposed new 3-15cwt. Arrangement of HQ provided that the trucks are properly fitted, but the necessity of aerial bosses in field section trucks in addition to fitments affecting transport alone (see section 1 above) is emphasised. It is also suggested that it would be advantageous to add say 30 to 50 feet of cooper wire, say R5, to the equipment of HQ, Microphones and AP's, for Use as aerial in sites where considerations of concealment and microphone sitting render it impossible to obtain a rod aerial in a sufficiently unscreened position. 7. Modulation. It is established that the signal strength originated at the microphone is adequate, but it seems that modification of the design of the microphone modulation circuit might tend to improve the strength of the transmitted signal. In these trials, the increase of aerial length at microphone tended to overcome weakness in transmitted signals to a sufficient extent, but it should be noted however that in the trials on the 21^st (Exercise NUTS) the interchange of Senders between M4 and M5 resulted in an increase in transmitted signal strength at M5, without a corresponding increase with the old M5 set when used at M4, thus suggesting that the weaker signal from the original M5 Sender was a function of the Set rather than range or position. /to page five.

Radio Link Trials (Page 5).

(8) The general performance of the equipment after adjustment by Ordnance was immeasurably superior to that when first issued. It is suggested that when equipment is first issued, it is put into service, say, for a month or so, and then sent in to Ordnance Workshops for checking and adjustment, much in the same manner as a new vehicle is checked after being run in. In general, it is considered that the present equipment is established as a workable unit which will produce good results by day, and possibly also by night. The night performance is not yet established, but it seems likely that with practice, operations may be able to read through interference and produce locations. It should be remembered however that these results and indications have been obtained with equipment straight out of Ordnance Workshops and that no indication is given that without improved fittings for carriage in unit transport, the equipment will continue in its present condition.

Goudhurst, L.G. Lewzey 24/Feb/42 Major R.A. Commanding S.R. Battery, 7^th Survey Regt. R.A.