# Why are the frequencies unevenly spaced on old-style analog radio tuners?

**URL:** <https://boards.straightdope.com/t/why-are-the-frequencies-unevenly-spaced-on-old-style-analog-radio-tuners/108918>\
**Category:** Factual Questions\
**Created:** [May 13, 2002, 11:29pm UTC](https://boards.straightdope.com/t/why-are-the-frequencies-unevenly-spaced-on-old-style-analog-radio-tuners/108918 "2002-05-13T23:29:04Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![Hyperelastic](https://avatars.discourse-cdn.com/v4/letter/h/a3d4f5/32.png) [@Hyperelastic](https://boards.straightdope.com/u/Hyperelastic)\
**Post date:** [May 13, 2002, 11:29pm UTC](https://boards.straightdope.com/t/why-are-the-frequencies-unevenly-spaced-on-old-style-analog-radio-tuners/108918/1 "2002-05-13T23:29:04Z")

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Well?

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**Author:** ![yabob](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/yabob/32/2821_2.png) [@yabob](https://boards.straightdope.com/u/yabob)\
**Post date:** [May 13, 2002, 11:45pm UTC](https://boards.straightdope.com/t/why-are-the-frequencies-unevenly-spaced-on-old-style-analog-radio-tuners/108918/2 "2002-05-13T23:45:36Z")

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Because the physical positions displayed measured some linear adjustment of a tuning device, like how far a ferrite slug was inserted into a coil. The actual frequency response to that setting is logarithmic, hence the compressed settings at one end of the dial.

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**Author:** ![David\_Simmons](https://avatars.discourse-cdn.com/v4/letter/d/9de053/32.png) [@David\_Simmons](https://boards.straightdope.com/u/David_Simmons)\
**Post date:** [May 14, 2002, 3:13am UTC](https://boards.straightdope.com/t/why-are-the-frequencies-unevenly-spaced-on-old-style-analog-radio-tuners/108918/3 "2002-05-14T03:13:08Z")

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> [@](#):
>
> \*Originally posted by yabob \*  
> \*\*Because the physical positions displayed measured some linear adjustment of a tuning device, like how far a ferrite slug was inserted into a coil. The actual frequency response to that setting is logarithmic, hence the compressed settings at one end of the dial. \*\*

I don’t know how “old time” you mean. However, tuning used to be done either by a ferrite (magnetic) slug in a coil or by a variable capacitor. The capacitors were manufactured in two varieties, linear capacity or linear frequency. The linear capacity version was cheaper but, like the ferrite slug in the coil, gives a non-linear frequency tuning curve. More expensive sets used the linear frequency model that had logarithmically shaped plates to get the linear tuning curve.

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**Author:** ![Hyperelastic](https://avatars.discourse-cdn.com/v4/letter/h/a3d4f5/32.png) [@Hyperelastic](https://boards.straightdope.com/u/Hyperelastic)\
**Post date:** [May 14, 2002, 6:45pm UTC](https://boards.straightdope.com/t/why-are-the-frequencies-unevenly-spaced-on-old-style-analog-radio-tuners/108918/4 "2002-05-14T18:45:04Z")

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Thank you!