[RTTY] kenwood ts 850 filters for rtty.

[Jeff Blaine]

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 at 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 at 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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