[NLRS] DEMI 2304 transverter

Sat, 02 Feb 2002 02:23:19 -0600

At 18:34 01-02-02 -0600, Jon C Platt wrote:

Hi Guys,
I'm not sure if my 2304 unit is "current" or not... but I strongly suspect
that it is.  Its serial number 148, and has 1w output in the 10x4x2" case.

I just fnished sweeping the response.  UUT was the entire receive side of
the transceiver, from RF input to i.f. output.  Even though I had to use
fairly high input levels to get a measurable i.f. output (no 144 MHz
receiver), I think I kept the test setup reasonable:  input power low
enough to not saturate the receiver/mixer chain, output falls in the
dynamic range of the detector, etc.
The numbers:
- 10dB (low side)		2273 MHz
- 6dB (low side)		2279
- 3dB (low side)		2286
Max signal transfer	2296
- 3dB (hi side)		2324
- 6dB (hi side)		2360 
- 10dB (hi side)		2392 
- 13dB			2402 MHz

As you can see, the shape is NOT symetrical about 2304.  It favors the high
side from 2304... maybe it was even designed to be reasonable broad toward
2400 !  The 13 dB difference can easily be made up with antenna gain,
preamp, etc.  Satellite isn't really a "weak signal" mode... at least not
Earth-orbit ones.  Mars Surveyor on the other hand....

Hope this helps.

73 Donn
WA2VOI/0  

>Hi John.   I believe that I have one of the newer 2304 DEM transverters.
>The front end is wide open, then is followed with a hair pin filter, a MMIC,
>a second hair pin filter, a second MMIC, then the signal goes into the
>receiver mixer to mix with the LO.   No filtering that I can remember on the
>144 receive out from the mixer.
>
>The question may be as to what the bandwidth is on those hair pin PCB
>filters ..... if they are centered around 2304 can they cover 2400 ??
>Don't know, I'd tend to bet not.   Perhaps LJC or someone else has some
>thoughts as to the bandwidth of these three section PCB hair pin filters.
>
>73, Jon
>W0ZQ
>
>
>----- Original Message -----
>From: "John P. Toscano" <[email protected]>
>To: <[email protected]>
>Sent: Friday, February 01, 2002 9:32 AM
>Subject: [NLRS] DEMI 2304 transverter
>
>
>> Do any of you have one of the recent vintage Down East Microwave
>> 2304 transverters?  If so, can you tell me if the front-end filtering
>> is tight enough to exclude reception in the 2400 MHz satellite
>> sub-band?
>>
>> I'm seriously considering the addition of a 2304 transverter, at the
>> time (this Spring) when all the other antennas go up.  I was going to
>> use a modified MMDS downconverter for the Oscar-40 2.4 GHz downlink,
>> but I could simplify the cabling and switching quite a bit if the
>> 2304 transverter could also hear well enough at 2400 MHz by simply
>> tuning my IF radio to 240 MHz instead of 144 MHz.  Then I wouldn't
>> need a second box just for hearing Oscar-40.
>>
>> I'm guessing that the answer is probably NO, but the DEMI folks are
>> "out of the office" until February 18th, so I thought I'd try to tap
>> the brains of you guys in the meantime.
>>
>> 73 de KB0ZEV
>> _______________________________________________
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>
>
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