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Vintage Amateur and Military Radio Amateur/military receivers and transmitters, morse, and any other related vintage comms equipment.

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Old 14th Feb 2018, 5:10 pm   #1
deliverance
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Default AR-88LF. Tuning box.

Hi all , My 88 has backlash in the tuning box I read somewhere that someone had posted up a thread regarding this but I can't find it any help with this would be appreciated thanks Chris .
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Old 14th Feb 2018, 6:57 pm   #2
Radio Wrangler
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Default Re: AR-88LF. Tuning box.

There shouldn't be any backlash if it's been assembled properly. All the gears mate with doubled ones which are sprung apart. If someone throws it together without pre-loading the springs you get backlash..... also if the bearings are worn or loose.

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Old 14th Feb 2018, 6:59 pm   #3
G6Tanuki
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Default Re: AR-88LF. Tuning box.

There shouldn't be backlash. The design of the large tuning-gears is that they are each made of two separate gears whose mesh with the other gears is controlled by small coil-springs interposed between them so the two large gears are kept in tension.

What can happen though is that over the intervening decades the original lubricant can go hard - this then essentially glues the two gears together and prevents the anti-backlash springs from doing their thing.

The answer is of course to strip out the gearbox, separate the pairs of gears [watch out for flying springs!] and use a suitable solvent to remove all the old congealed grease - then reassemble using a light oil or semi-fluid grease [I use the 'moly-grease' intended for constant velocity joints on front-wheel-drive cars].

It takes time and effort, but you should be rewarded with a velvety-smooth backlash-free tuning drive.
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Old 14th Feb 2018, 7:36 pm   #4
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Default Re: AR-88LF. Tuning box.

I have a spare recovered AR88 tuning assembly no idea about the condition until I drag it out.

However I agree with the previous comments the old lubricant becomes a sort of yellow glue!

Cheers

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Old 14th Feb 2018, 8:26 pm   #5
deliverance
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Default Re: AR-88LF. Tuning box.

Thanks for your replies guys the springs that keep the tension on the split gears are loose so I guess that's not helping . I will remove the box on Friday (day off) and let you know .
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Old 14th Feb 2018, 10:36 pm   #6
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Default Re: AR-88LF. Tuning box.

Chris,

Here's two threads linked below which may be the ones you saw.

https://www.vintage-radio.net/forum/...d.php?t=117076

https://www.vintage-radio.net/forum/...ad.php?t=77441

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Old 14th Feb 2018, 11:59 pm   #7
deliverance
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Default Re: AR-88LF. Tuning box.

Excellent Andrew thanks some good details and pics from Gezza and co should help me get to grips with it .
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