Hams in the the eastern half of Oz will be quiet on the bands Sunday 24th Feb as we head to the Wyong Field Day hamfest, about 1.5 hr north of Sydney. This is our biggest swapmeet in Australia (potentially southern hemisphere) & anyone whos anyone will be there to trade old & new radio & electronic gear & have our annual face-to-face catchup. Locally, the bands are even quiet now as people prepare themsleves; organising cash, lines of credit, filling esky's & loading gear to offload at the hamfest. Fun for everyone.

Many members in our Sydney based club MWRS (www.mwrs.org.au) are driving up or hitching lifts obscenely early. Some are even attending the pre-hamfest "Contester University" to bone up on the finer points of contesting. One of our members takes his XYL every few years just to show her that he's not that weird after all !

See you there?
Dom VK2JNA

http://www.fieldday.org.au/

A friend in our club, the  Manly-Warringah Radio Society, is having trouble locating these HP 8591E Spectrum Analyzer Service Manual & ccts for repairs. Any suggestions? Anyone with a pdf somewhere?

tnx

dom

(the 511 is a re-badged 230)

Nature of the failure:
When the 511 tuner is first powered up, it tunes when a carrier is present. We can see this by installing an SWR meter in line. On second & subsequent changes of frequency & carrier insertion, there is no further tuning; it just seems to stay at the first setting. If we cut the 12v power & re-power up, the coupler will tune again but not for second & subsequent frequency changes...

The installation is in a friend's yacht, where the coupler is inside a cupboard in the middle: the earth is heavily strapped (copper sheet) to metal keel & the antenna wire runs horizontally internally for about 3m (~12ft) before attaching to the backstay which is about 20m (~66ft) long & insulated before the mast.

We have debugged the system by taking out the 511 & using an original SG-230, which worked perfectly. We have since bench tested the two side-by-side & discovered the exact nature of failure explained above.

We have copies of SG-230 manuals (with schematics) from SGC website. These are for the newer versions that have 68HC11 microprocessors.

Q1 Has anyone got a copy (pdf or other) of the older manual (& specifically, the schematic) for the tuner (Barrett 511 or SG-230) that used the 6805 microprocessor?

Q2 Based on symptom, could anyone give us an idea of what part of the circuit we should look more closely at? We are technically minded & would like to attempt to solve this puzzle.

Does the 1/4 wavelength section need to be coupled closely or loosely to the braid of the coax? I know it is connected at the end away from the antenna but what determines the inside diameter of the sleeve. If I was using RG58 of ~5mm OD, does it matter if I use 6mmID copper tube or 10mm? I cannot find anything in literature anywhere in ARRL or on the web defining this dimension.

thanks