Re: [amsat-bb] Why V/S in stead of U/S

["Edward R. Cole" <al7eb@xxxxxxxxxxxxx>]

At 01:28 PM 5/25/2005 -0400, kb2m wrote:
> Has anyone actually done the 430 MHz mod to the 2880 Drake described 
>here...
>
>http://www.ne.jp/asahi/m-arai/gkz/sband/mod32e.htm
>
>73 Jeff kb2m

Jeff,

I have two Drake converters.  One is unmodified running at 2401/123-MHz.
The other is modified using a 7.68 MHz xtal from Mouser PN 520-HCU768-20
(20 pF).  A good friend of mine did the conversion basically following the
website you listed.  He also added a feedthru capacitor for powering it
with a separate line (not thru the coax as the original Drake did).

The 7.68-MHz xosc is multiplied x256 = 1966.080 MHz.  The corresponding IF
is 434.920 MHz.  It can be tweeked up to 435-MHz.
The xosc drifts for about the first 30-minutes after power-up.  Mine
settled out at 434.995 so my readout is 5-KHz low.

I found that the "plain" Drake without any RF input modification, was
pretty "deaf".  Noise Figure is reportedly about 5 to 7 dB.  I could not
hear AO-40 using a 4-foot dish and the Drake by itself.  Adding a good low
noise preamplifier cured that and made a terrific combination.  I bought
the Kuhne Engineering MKU-232A2 measured at 0.6 dBNF and 41 dBG.

Its hard to know if the "plain" Drake will be adequate with AO-51.  You
need to ask others about that.  I have not tried it on AO-51.
 
73's,
Ed - KL7UW  <new call>
===================================
BP40iq,  Nikiski, AK      http://www.qsl.net/al7eb
Amsat #3212
Modes: V - U - L - S
===================================
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