[Boatanchors] Linear Tuning in VFOs -- SFW and SFL Variable Capacitors
howard holden
holden7471 at msn.com
Mon Sep 5 23:29:19 EDT 2022
Might also depend on the type of receiver. A general coverage type will almost always be bunched up at the high end of a dial. There are/were also capacitors designed and cut – generally not all that great, and mostly in the 1920s-30s-40s - to simulate equal tuning regardless of which end of the band.
Howie WB2AWQ
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From: Nick England<mailto:navy.radio at gmail.com>
Sent: Monday, September 5, 2022 5:18 PM
To: anchor at ec.rr.com<mailto:anchor at ec.rr.com>
Cc: boatanchors at mailman.qth.net<mailto:boatanchors at mailman.qth.net>
Subject: Re: [Boatanchors] Linear Tuning in VFOs -- SFW and SFL Variable Capacitors
Well, there are always exceptions…
TMC used capacitor tuned oscillators with a cam mechanism to provide
linearity.
I believe the Heathkit SB-series master oscillators were capacitor-tuned as
was the Hallicrafters SX-115.
Things from dim memory so probably subject to correction.
Nick K4NYW
On Mon, Sep 5, 2022 at 7:51 PM Al Parker <anchor at ec.rr.com> wrote:
> Hi Bill,
> It's cuz some have PTO (permeability tuned) oscillators (usually a
> slug
> moving thru and inductor.) and some have capacitive tuned osc. Drake
> has PTO's mostly, as does Collins, SP-xxx's, most if not all Halli's use
> a variable capacitor.
> 73,
>
> Al, W8UT
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> "There is nothing -- absolutely nothing -- half so much
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> Ratty, to Mole
>
> On 9/5/2022 1:11 PM, Bill Meara via Boatanchors wrote:
> > Drake 2-B! HT-37! SP receivers! HQ-100s Why do some rigs have nice,
> linear tuning, while others havethe frequencies bunched up at one end of
> the tuning range? Enquiring hams want to know!
> >
> https://nam12.safelinks.protection.outlook.com/?url=https%3A%2F%2Fsoldersmoke.blogspot.com%2F2022%2F09%2Fwhy-do-some-vfos-tune-more-linearly.html&data=05%7C01%7C%7C207b8031355c4363263008da8f9d4ade%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7C1%7C0%7C637980202972874476%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&sdata=Ek1%2BFKUr4Hfh0aVSCeOWdDlUqj3ezwXnT%2FXVPRBObO8%3D&reserved=0
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> > 73 Bill N2CQR
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Nick England K4NYW
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