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Re: 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



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