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Volume XLI THE SHORT WAVE MAGAZINE 365

The Datong Model SRB2 Automatic Woodpecker Blanker.

AUTO wooopecker blanker

— ON łOHi IN

blanker

active

-CL OfF

On CW, it is likely that the less experienced operator may have difficulty in reading through the holes and, if copying letter by letter, may end up with a somewhat garbled message pad, depending on the speed of sending. This is where the morę experienced CW addict, who recognises whole words rather than individual letters, will cope much better.

The operating instructions consist of five, typewritten A4 sheets and include a section on getting the best results from the SRB2. These hints include using a faster-than-usual AGC setting and reducing the receiver RF/IF gain if any AGC “pumping” is noticed when receiving unusually wide pulses. Both these suggestions proved helpful. There are two intemal adjustments which can be madę which necessitate removing the works from the case. The First is to vary the drop-out time of the RF actuated antenna relay, while the second enables the user to set the sensitivity level at which blanker begins. Unfortunately, the four case-fixing crosshead screws were so tightly driven home that it was impossible to loosen them, hence no photographs of “the innards” this time.

The SRB2 was used with an Icom IC-730 transceiver and it certainly cut out the very strong pulses from the usual kind of Woodpecker transmission in a very convincing manner. There are a couple of minor points worthy of mention, though. The First is that, late at night, in the 14 and 18 MHz bands, the Woodpecker sounded rather morę “hollow” and “softer” than usual, and with apparent selective fading the SRB2 had only marginal effect on such signals, even though the “Blanker Active“ LED conFirmed the circuits were in. The second is that the Datong literaturę States “. . . the AF blanker removes any remaining clicks from the loudspeaker.” However, in the reviewer’s installation, this proved not quite true, there being some slightly annoying clicks audible.

To sum up, this ingeniousaccessory should greatly enhance the performance of most receivers and transceivers, particularly those designed before the notorious Woodpecker was hatched. The Auto Woodpecker Blanker Model SRB2 is designed and manufactured by Datong Electronics Limited of Spence Mills, Mili Lane, Bramley, Leeds, England, LS13 3HE, to whom thanks are due for the loan of the review model. It can be bought either direct or through various dealers, the current cost being £75, plus VAT of £11.25 for U.K. purchasers.

N.A.S.F.

Appendix

The SRB2 was demonstrated at the RSGB’s National Amateur Radio Convention in Birmingham on March 5/6 this year and many potential customers have wondered why it has taken much longer than usual to appear on the dealers’ shelves. The story is a very intriguing one. Because earlier novel designs had been copied abroad, Datong decided to File a patent application for this one before exposing the prototype at the Hanwention in Dayton, Ohio, at the end of last April. In mid-May, the Company received a letter from the Patents OfFice forbidding communication of any details of the invention to anyone until it had been vetted by the Ministry of Defence, in case it contravened the OfFicial Secrets Act.

The Company was then in the embarrassing position of having bought in considerable stocks of components and being in receipt of Firm orders from customers, yet unable to honestly explain the real reason for the delay. The matter was not resolved until June 30, by which time the sales effort had lost a lot of momentum. As Dr. Tong points out, what would have been his position if fuli details of the circuitry had been revealed at Dayton, but thereafter the OfFicial Secrets Act had been invoked to prevent production?

This must have been a traumatic experience for such a smali, innovative Company and a salutory reminder of the powers of the State in a “free’ ’ country. By way of compensation, it would be of some comfort to wonder if the MoD would commission Datong Electronics Limited to design some electronic counter measures eąuipment!