[HBR] Relay switched coils?

[Peter Bertini]

T'would be nice if someone could engineer a duplicaticable plug-in coil
system, as used in the National HRO receivers. That would solve a lot of
problems, including trying to herd cats.. errr, a huge pile of loose plug in
coil forms that could be easily damaged or lost. National's tuning system
using a right angle drive solved a lot of the mechanical layout problems.

Didn't someone come up with scheme using the RF decks from old ARC-5/Command
surplus RXs for this purpose?  I'm still wrestling with ideas for my HBR
project; and the frontend tops the list.

Pete

On Mon, May 31, 2010 at 7:31 AM, Bill Cromwell <wrcromwell at gmail.com> wrote:

> Hi Walt,
>
> For relay switching there are also issues of oxidation on the relay
> contacts. The oxidation, even minor oxidation, degrades the performance.
> A solution for that is to apply a voltage across the contacts and the
> current will clean the contacts. Reed style relays will have contact to
> contact "scrubbing" and that abrasion will scrub the oxidation off
> without resorting to the extra trouble of the aforementioned
> voltage/current.
>
> I'm a fan of plug-in coils for their simplicity, reliability, and
> uncompromised performance. For miniaturizing radios, even toroidal form
> factors on high Q cores can be plug-ins. With plug-ins we have to be
> careful to not lose them during field operation. Of course, the plugging
> action cleans the contacts.
>
> 73,
>
> Bill
>
>
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