[Lowfer] TS-890

[wa3tts at verizon.net]

Doug, Zack Jon & All:  Try terminating your unused RF and IF ports on your new radios into 50 or 75 ohm termination connectors. Doing so here in my station seems to be making a difference with my FT-817s and FT-847 radios used as IF radios for my MF/LF converter reception for improving WSPR decoding performance at higher -SNRs.
At the W3SO VHF contest station we had some radio-to-radio interference with the Elecraft K3s.  Most of that interferece was at the intermediate frequencies with the K3's only several feet apart on a long operating table. Putting terminations on the unused rear panel IF ports and transverter ports as well as making sure those ports were switched "off" in the  K3's software menu made a noticeable difference in low noise receive performance.
Its simple stuff, but easy to forget.  I would think that an unterminated port on a PIN diode A/B switch inside a radio would not be anywhere near the 60~65 dB isolation that is often quoted or assumed.  The combination of high impedance and light capacative coupling in such an unterminated circuit could conceivably allow undesired LF and MF energy transfer....a look at those small value interstage coupling caps used in W1VD's 500 kHz Preselector should be a clue that small "C" values allow energy transfer in Hi-Z circuits....possibly resulting in undesired noise ingress....

73, Mike wa3tts

-----Original Message-----
From: JJ via Lowfer <lowfer at mailman.qth.net>
To: lowfer at mailman.qth.net
Sent: Thu, Oct 8, 2020 6:53 pm
Subject: Re: [Lowfer] TS-890

I had a transceiver, maybe an IC-746 that wouldn't go below 30kHz but if 
I engaged the RIT the RIT would bring it lower.
73,
Jon WS1K

On 10/8/2020 2:02 PM, Douglas Williams wrote:
> It arrived today. I didn't expect it to be quite so......ginormous (and
> heavy). It dwarfs my R-75. I'm going to have to build a shelf for my little
> table if I want to add any accessories.
>
> https://i.imgur.com/qbazcls.jpg
>
> It seems quite sensitive at LF. I heard the usual daytime airport NDBs, and
> the close ones were S9+. WWVB is S9+10 and some MSK station around 40kHz
> was S9+10. It will not tune lower than 30 kHz.
>
> On Wed, Oct 7, 2020 at 4:35 PM Douglas Williams <williamsdoug1966 at gmail.com>
> wrote:
>
>> Zack,
>>
>> Gratz. Always fun to play with new toys. :-)  This new generation of
>> transceivers is amazing.
>>
>> D.
>>
>> On Wed, Oct 7, 2020 at 4:30 PM Zack Widup <w9sz.zack at gmail.com> wrote:
>>
>>> I just got an FT897D. Nowhere hear the bells and whistles of that radio
>>> but
>>> it is a great small radio for portable operation, plus it has 144 and 432
>>> MHz, too.
>>>
>>> But I was tuning around in the NDB LF band as well as 475 kHz with it the
>>> other night. The FSK CW beacon (I forget the call now) on 475 kHz was just
>>> booming in on the radio and I heard a lot of NDB's between 250 and 450
>>> kHz.
>>>
>>> 73, Zack W9SZ