29regatta
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1929 Hobart Regatta ex 7HR log book Richard Rogers VK7RO 3/12/2004 all my comments are in square brackets[ ] [In 1925 the Launceston Radio Club experimented with a transmitter on a boat during the Launceston Regatta. There were problems with frequency stability using a simple single valve transmitter caused by the aerial capacitance varying as the boat rolled. In February 1929 the Hobart Radio Research Club operated their club station VK7HR on the Marine Board vessel Toorah and sent descriptions of the Hobart Regatta events for relay by the broadcasting station 7ZL in Hobart. Frequency stabillity problems were avoided by using a crystal controlled transmitter. In the photo caption, I have called 7ZL the ABC, but in 1929 7ZL was operated by Tasmanian Broadcasters Ltd. There followed the Australian Broadcasting Company in 1931 and the Australian Broadcasting Commission in 1932. Here are the relevant log entries from the 7HR log book. Note that the prefix VK was used from January 1929 and the portable call was XVK7HR.] Jan 5 1929 QSO VKX7HR (portable on ss Toorah - 7DX in charge) [evidently they must have been testing different microphone setups] X7HR R8 CW R6 phone mod abt 70% Nr 1 breath seems to be troubling it Nr 2 background engine noises Nr 3 CW pdc no background noises when mike off 3V bias 4 1/2V better Nr 4 . . . nr 1 mike very much same but different tone & find bit better February 4th X-VK7HR Permission for tests obtained by Mr Sweeting 7ZL 8.30pm Installed portable CC transmitter and cage aerial on SS Toorah at Hobart wharf 9.00pm On the air telephony 84 metres input 7.2 watts Earth wire to Kingston valve sea water circulation pump in engine room Aerial current with 275 volts = .25amp 10.30pm Tested with VK7LJ who was on 42M band R 5/6 CCDC QSA 4/5 Power leak interference bad both at 7LJ and X-VK7HR (7LJ to be on board at 8.15am) 11pm Signed off closed down Operator W.T.Watkins [VK7DX] February 5th Regatta Day 8.15am Arranging and connecting up gear again. 9am On the air 84M 300volts x 23mA amplifier Aerial current = .21amp Cruising up and down River Derwent with Mr Sweeting of 7ZL on microphone describing racing, swimming & rowing events which was being received by 7ZL SW receiver in city. 9.15am Two way contact with VK7JK (42M) X-VK7HR 84M Throughout the day description of races given. Inductances and sets were vibrating to some order but the crystal functioned perfectly. Clear steady carrier. 1.30pm 7LJ at club room transmitter 7HR & two way contact had. 7HR = qsa 4 r 5 rough note! Reports on X VK 7HR telephony were qsa 5 clear steady pdc carrier After testing closed off for lunch with Capt Watchorn, Engineer McGlauclan and some others. On and off during afternoon. Closed off 4.30pm Summing up the results of experiment we found. portability of HT supply needed Also of equipment where possible Strength & durability of apparatus. All equipment be strapped or tightened down to benches or walls. And non microphonic receiving valves. We had only one minor accident due to a heavy swell of sea Boat rolled and three batteries fell onto the floor. With the Crystal it was possible to maintain a perfectly steady and pure dc wave under Ship Roll. Engine vibration and bumping alongside wharf. Telefunken system of modulation was used. Equipment used : - Cage aerial 50 feet length Rings 5" dia HT supply = 300 volts batteries LT supply = three 6 volt A batteries "C" = 45 volt and a 4 1/2 volt unit Crystal oscillator 84M Amplifier same wave neutralized. Receiver = 0 - V - 1 De5 det Dep610 Audio Microphones were W.E., Baldwin and Erriccson A very successful and interesting day was had in company of VK7LJ [Lon Jensen] (Report by VK7DX W.T.Watkins)