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Re: AW: FT736r recieve gain variations?



Hi Al,

You may find that just changing the cable length to our second converter
wil solve your problem.  I have had similar problems on 10 meters with a
seperate receive input and changing the cable length changed the "suck
out" frequency.

Good luck,

73 de Jess - W4MVB

On Tue, 06 Nov 2001 10:02:53 -0500 al lawler <alawler@oracle.com> writes:
>
>   Just a followup - I found the source of my (really huge) 
>deline in recieve performance in the vicinity of the AO-40
>beacon.
>
>  It wasn't my FT736r at all.  The problem was caused by the
>Hamtronics downconverter which I have also have connected to
>the 2m converter output via a "Tee" connector.  (I use the 
>hamtronics converter to drive a separate 10m telemetry
>reciever.)
>
>  I need to dig out the hamtronics schematic - I'm hoping
>I can either re-tune (or de-tune) the input slightly such that 
>this isn't as much of an issue.
>
>  Without the hamtronics converter in the recieve chain,
>the signal from the DEM preamp/3733 converter is more
>than enough.  Now I just have to wait for AO-40 to stop
>hiding behind the trees...  :^)
>
>  -al
>  WB1BQE
>
>
>
>
>
>Paul Kupper wrote:
>> 
>> Hi Al,
>> 
>> I had similar problems with my Icom IC-475 70cm transceiver. There 
>where several
>> holes spread around the whole band. Audio was muted in FM but not in 
>SSB and I could
>> not transmit. A adjustment of the PLL cured the problem. The PLL was 
>out of lock at the
>> edges.
>> 
>> 73 de Paul
>> HB9OMQ
>> 
>>   I've noticed that the recieve gain on my ft73r appears
>> to take a severe nose-dive between 145 and 146 mhz
>> (with the lowest reading right around 145.350 in the
>> range of the ao-40 beacon... :^(
>> 
>>   I had originally noticed this effect with my drake
>> converter, which was 250khz off in frequency, and
>> attributed it to the drake,   but now my newly modified
>> trans-system (which is on frequency) does a similar
>> thing.  The "dead spot" occurs at the same 2 meter
>> frequency, which would seem to rule out the converter,
>> or a null in the antenna gain etc.
>> 
>> 
>> 
>>   With the antenna pointed at the daytime sky with
>> the transystem in line (and a 24dbi bbq dish),  here
>> are the no-signal white-noise s-meter readings I see
>> as I  tune across the band on the ft736r.
>> 
>>   144 mhz -- S9
>>   144.5   -- s9
>>   145     -- s6.5
>>   145.350 -- s0  (the noise gets louder at 145.400 mhz.)
>>   145.5   -- s2
>>   146     -- s6.5
>>   145.6   -- s7
>>   147.0   -- s7.5
>>   147.5   -- s8
>>   147.999 -- s8
>> 
>>   Can somebody with an FT736r do a similar experiment and
>> let me know if they see the same type of 'dead spot'?
>> (Prior to today, I've never tried to listen in that particular
>> part of the band, so I don't know if this is normal for
>> the rig or not...)
>> 
>>   THanks,
>> 
>>   -al
>>   WB1BQE
>> 
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