[Date Prev][Date Next][Thread Prev][Thread Next] - [Date Index][Thread Index][Author Index]

Re: CalAmp DownConverter Info



The CalAmp  down converter is similar to the Drake 2880 that was sold a few
years back.

To lengthen the strip lines cut a couple of resistor or capacitor leads to 3
mm. Solder the leads to the end of the strip lines extending them to about 1.5
mm.

Here are some links on the Drake conversion.

 http://members.aol.com/k5oe/drake.htm<http://members.aol.com/k5oe/drake.htm>
http://www.markfossum.com/NewFiles/2880.pdf<http://www.markfossum.com/NewFile
s/2880.pdf>
http://www.ne.jp/asahi/hamradio/je9pel/conv2880.htm<http://www.ne.jp/asahi/ha
mradio/je9pel/conv2880.htm>
http://www.nitehawk.com/rasmit/mds2880cv.html<http://www.nitehawk.com/rasmit/
mds2880cv.html>
http://www.g0mrf.freeserve.co.uk/drake.htm<http://www.g0mrf.freeserve.co.uk/d
rake.htm>
http://www.ghengineering.co.uk/g8ubn/drake/<http://www.ghengineering.co.uk/g8
ubn/drake/>

Googling Drake 2880 will bring up more information.

Good luck!

Dave / W6TE

  ----- Original Message -----
  From: Robin Callender<mailto:robin_callender@hotmail.com>
  To: amsat-bb@AMSAT.Org<mailto:amsat-bb@AMSAT.Org>
  Sent: Thursday, June 09, 2005 2:58 PM
  Subject: Re: [amsat-bb] CalAmp DownConverter Info


  Hi Roger,

  I was wondering if you have any recommended web pages describing how to use
  brass shims and teflon tape to rework comb filters.
  I too bought one of these units, and am now watching the bb and hoping to
  glean some tech info on it.

  73s
  Robin
  KE7ARL


  ----- Original Message -----
  From: "Rogerkola" <Rogerkola@aol.com<mailto:Rogerkola@aol.com>>
  To: "Bill Ress" <bill@hsmicrowave.com<mailto:bill@hsmicrowave.com>>;
<amsat-bb@amsat.org<mailto:amsat-bb@amsat.org>>
  Sent: Thursday, June 09, 2005 11:33 AM
  Subject: Re: [amsat-bb] CalAmp DownConverter Info


  > Hi Bill...
  >
  > Just some ideas reguarding your points:
  >
  >> The biggest problem is the 7 pole combline filter right at the input
  >> covering 2.5 to 2.7 GHz. Tuning it down to 2.4 GHz proved unsatisfactory
  >> since the tuning screws were already almost touching the resonators.
  >
  > In the past the comb filters have been lengthened with brass shim stock or
  > capacitivly lowered with teflon tape...could this work here?
  >
  >>To convert the unit to 2401 would require removing (by-passing) the input
  >>filter, some slight input amplifier matching circuit tweaking, and
  >>conversion of the LO to 2257 Mhz.
  >
  > Would this be necessary if the original IF of 123 MHZ is retained with the
  > proper receiver?
  >
  >>100 to 350 MHz IF amplifier which has both high pass
  >> and low pass filter elements for the IF band.
  >
  > Did you have a chance to measure the cutoff characteristics of the high
  > pass filter to see if it would pass 121 Mhz without loss? Possibly the
  > high pass filter could be bypassed?
  >
  > I guess the bottom line would be to measure the gain and noise figure in
  > it's current form and to decide if it was worth a conversion.....
  >
  > Just my thoughts outloud...
  >
  > Roger
  > WA1KAT
  >
  >
  >
  > ----- Original Message -----
  > From: "Bill Ress" <bill@hsmicrowave.com<mailto:bill@hsmicrowave.com>>
  > To: <amsat-bb@amsat.org<mailto:amsat-bb@amsat.org>>
  > Sent: Thursday, June 09, 2005 1:24 PM
  > Subject: [amsat-bb] CalAmp DownConverter Info
  >
  >
  >> Since the responses to my post indicated that I should post this
response
  >> for all - here's what I have...
  >>
  >> The unit is for the MMDS/ITFS band which is 2500 to 2690 MHz. This is
the
  >> instructional TV band also used by some wireless pay TV services.
  >>
  >> I purchased the unit for parts: connectors, IC's, transistors, a great
  >> weather protected cast housing, etc., knowing that conversion would be
  >> questionable and I think you'll agree.
  >>
  >> The biggest problem is the 7 pole combline filter right at the input
  >> covering 2.5 to 2.7 GHz. Tuning it down to 2.4 GHz proved unsatisfactory
  >> since the tuning screws were already almost touching the resonators.
  >>
  >> The LNA uses a device yet to be identified followed by a R37 (believed
  >> this
  >> is a NEC device).
  >>
  >> The mixer uses a pair of Schottky diodes (smd = C2) and a 3 dB branch
  >> line
  >> coupler. This circuit is typically somewhat broadband and should work at
  >> 2401 MHz.
  >>
  >> This is followed by a 100 to 350 MHz IF amplifier which has both high
  >> pass
  >> and low pass filter elements for the IF band.
  >>
  >> The unit is internally down regulated to 12 volts. Power is applied via
a
  >> bias tee to the type "f" 75 ohm output connector. While the type "f"
  >> connector and output circuit has been designed for 75 ohms, driving 50
  >> ohms
  >> is no problem.
  >>
  >> The LO is a crystal controlled PLL using a 2380 MHz VCO divided by 256 by
  >> a
  >> Fujitsu MB506 (divide by 256) and locked to a crystal at 9.29687 MHz.
  >>
  >> To convert the unit to 2401 would require removing (by-passing) the
input
  >> filter, some slight input amplifier matching circuit tweaking, and
  >> conversion of the LO to 2257 Mhz. This, in my opinion, could only be done
  >> by
  >> one having the expertise and test equipment. Looking at the 2380 MHz
VCO,
  >> I'm sure it could be pulled down to 2257, but again the right equipment
  >> and
  >> knowledge is needed.
  >>
  >> But I'm happy with the purchase (I got 2) since the N connectors alone
  >> are
  >> worth the price.
  >>
  >> If I can answer any other questions - email me.
  >>
  >> Regards...Bill - N6GHz
  >> ----
  >> Sent via amsat-bb@amsat.org<mailto:amsat-bb@amsat.org>. Opinions
expressed are those of the author.
  >> Not an AMSAT member? Join now to support the amateur satellite program!
  >> To unsubscribe, send "unsubscribe amsat-bb" to
Majordomo@amsat.org<mailto:Majordomo@amsat.org>
  > ----
  > Sent via amsat-bb@amsat.org<mailto:amsat-bb@amsat.org>. Opinions expressed
are those of the author.
  > Not an AMSAT member? Join now to support the amateur satellite program!
  > To unsubscribe, send "unsubscribe amsat-bb" to
Majordomo@amsat.org<mailto:Majordomo@amsat.org>
  ----
  Sent via amsat-bb@amsat.org<mailto:amsat-bb@amsat.org>. Opinions expressed
are those of the author.
  Not an AMSAT member? Join now to support the amateur satellite program!
  To unsubscribe, send "unsubscribe amsat-bb" to
Majordomo@amsat.org<mailto:Majordomo@amsat.org>
----
Sent via amsat-bb@amsat.org. Opinions expressed are those of the author.
Not an AMSAT member? Join now to support the amateur satellite program!
To unsubscribe, send "unsubscribe amsat-bb" to Majordomo@amsat.org



AMSAT Top AMSAT Home