[usa2003ardf] parts

[Kuon & Dale Hunt]

>Some interesting parts from Ocean State Electronics:
>http://www.oselectronics.com
>
>3.540 crystals (homing beacon), expensive at 9.65, but these are not
>common. part #CY3540.

    B. G. Micro has crystals for 3.5468 MHz for $0.30 each.
    That is what I have been using.  www.bgmicro.com

    At that price you can afford to put them in a whole set
    of transmitters!


>Ferrite rods for AM broadcast band for 2.95, part #LA540. Described as
>788uH.

    Some of the ferrite rods used for AM reception tend to get very
    lossy above 3 MHz, but it certainly is worth a try.


>A cheap plastic cap to resonate that ferrite rod, 15-140 pf, for 2.95,
>part #BC540.

    I've been keeping a close track of the available trimmer caps,
    since that can be one of the more expensive parts in my receiver
    kits.  Dan's Small Parts has a good selection, such as
    8 - 150pf for $1.50, 15 - 365pf for $2, and many smaller values
    for less than $1.

    Need to tune that 80m transmitting antenna?  Dan has 500 - 2500pf
    heavy duty mica trimmers for $2.50, among other values.

    He also has a number of varactors, including the MV2301 (120pf)
    at 5/$2, the BB104 (dual 35pf) at 20/$4, and a 15-piece kit with
    5 each BB104, BB605 (33pf) and BB505 (17pf) for $3.
    (Actually, I've had very good results using zener diodes for tuning
    in my receivers, besides they are cheaper and more commonly available.)

>
>So who will be the first to replace their loop with a ferrite rod? Maybe
>someone has already done it?

    The Ron Graham RX-4 and the German receivers all use ferrite rods.
    I haven't been very happy with the sensitivity of my RX-4, which
    might be due to a lossy grade of ferrite, the shield too close to
    the core, or a noisy IF stage.  However, the ferrite rod certainly
    is the way to go for small size.

    Someone explained to me that the air-core loops have a sharper
    pattern than a ferrite rod, but one had to be very good at plotting
    bearings and orienteering for it to make a difference in practice.


    By the way, I recently found a pair of old Radio Shack walkie-talkies
    that appear to be an ideal size for an 80m RX.  They already have the
    battery compartment built in, and the 49 MHz whip should work as the
    sense antenna (controlled by the PTT switch.)  But it will take a
    fairly short ferrite rod to fit inside the case...


    Good luck!

        - Dale WB6BYU