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Fw: CalAmp DownConverter Info



Seems QSL.net is down right now...if you google the links the cached pages 
will come up

Roger

----- Original Message ----- 
From: "Rogerkola" <Rogerkola@aol.com>
To: "Robin Callender" <robin_callender@hotmail.com>; <amsat-bb@AMSAT.Org>
Sent: Thursday, June 09, 2005 4:29 PM
Subject: Re: [amsat-bb] CalAmp DownConverter Info


> shimstock   http://www.qsl.net/n9zia/31732/
>
> shimstock   http://www.qsl.net/g3pho/drake.htm
>
> tape     http://www.qsl.net/n9zia/wc0y/
>
> tape     http://www.qsl.net/g0ory/2.3g/31732/31732.html
>
> ----- Original Message ----- 
> From: "Robin Callender" <robin_callender@hotmail.com>
> To: <amsat-bb@amsat.org>
> Sent: Thursday, June 09, 2005 3:58 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>
>> To: "Bill Ress" <bill@hsmicrowave.com>; <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>
>>> To: <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. 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
>>> ----
>>> 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
>> ----
>> 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
> ----
> 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
----
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



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