thanks Jeff, this technique is new to me(at 71+), and I will give it a
try...maybe old dogs can learn after all
73 john
On 7/23/2012 01:03, Jeff Blaine wrote:
> Don't discount the effect of the attenuator. I may have missed out the
> message thread but there was a comment on 160m CW down a couple of messages.
> That's a band/mode combo where an attenuator is a HUGE HUGE help.
>
> For the maximum IP3 performance (best DR3), add more and more attenuation to
> the front of the rig until there is no difference between the antenna
> connected with the attenuator - and the antenna disconnected without an
> attenuator. That works and is true for ALL receivers.
>
> Clicking on that attenuator is the most cost effective way to toughening up
> the rig from a IMD generation standpoint. And if you are talking about
> RTTY, using the attenuator and then letting the software decoder software
> provide the filtering function will give you the lowest cost and equivalent
> functional capability of multiple filters.
>
> This method works great on digital modes where the machine is doing the
> decoding. And if you need a filter in the rig (CW), then put it in the 1st
> IF if you are buying just one. As Joe mentioned, that will keep the down
> stream free of IMD products for the most part.
>
> Good luck!
>
> 73/jeff/ac0c
> www.ac0c.com
> alpha-charlie-zero-charlie
>
> -----Original Message-----
> From: Jamie WW3S
> Sent: Sunday, July 22, 2012 7:16 PM
> To: rtty@contesting.com
> Subject: Re: [RTTY] kenwood ts 850 filters for rtty.
>
> you cant beat a pair of stacked Inrad 400 hz, one in each IF....
>
>
> -----Original Message-----
> From: Joe Subich, W4TV
> Sent: Sunday, July 22, 2012 7:52 PM
> To: rtty@contesting.com
> Subject: Re: [RTTY] kenwood ts 850 filters for rtty.
>
>
> John,
>
>> I can only buy one filter, wanting the most filtering for blood and
>> guts 160 cw tests, but open enough to allow for fsk operation.
> When you say FSK operation that fairly clearly puts a "400 Hz" lower
> limit on the bandwidth and leaves you with two choices the 8830 KHz
> (1st IF) filter or the 455 KHz (2nd IF) filter.
>
> The 1st IF filter will provide a bit better RX IMD performance by
> getting the "narrow" filter earlier in the IF chain but the 2nd IF
> filter will provide slightly sharper skirts because of its lower
> frequency. You can see the filter curves at www.inrad.net.
>
> The 1st IF Filter is slightly less expansive than the 2nd. If it
> were me, I'd flip a coin and get one now and pick up the second one
> when conditions/finances allow. Ultimately you will want the pair.
>
> 73,
>
> ... Joe, W4TV
>
>
> On 7/22/2012 6:57 PM, john wrote:
>> I have bought back my 850 to use at my farm for dx/contesting/rtty.
>> there seems to be large number options/filters/if crystals.
>> due to finances I can only buy one filter, wanting the most filtering
>> for blood and guts 160 cw tests, but open enough to allow for fsk
>> operation.
>> any and all suggestions would be appreciate
>> mucho thanks....
>> 73 john w8wej
>>
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