Adding a Panadapter to the FT-990


Ed
 
Edited

Hello Group,
I noticed new member Pete, G4IOA, is adding a panadapter to his FT-990.

If anyone else on the group has any interest in adding a panadapter here's some information you may find quite interesting.

Years ago VE3TMT added a panadapter to his FT-990:

Link to 990 panadapter thread on QRZ that VE3TMT replied to:
https://forums.qrz.com/index.php?threads/yaesu-ft-990-gets-a-pan-adapter.594524/

The thread gives a detailed description of the steps Ripley KD8UYQ did to successfully add a panadapter to his FT-990 with some help from VE3TMT.

NOTE: Four years ago I was following a thread on QRZ where Ripley bought a Motorola EB104 600 watt PA board as the starting point to build a 600 watt amplifier.
I own an Ameritron ALS-600 amplifier and the design for the PA board is based on the EB104 design notes from Motorola, so I found Ripley's do-it-yourself design of a complete 600 watt solidstate amplifier very interesting and educational.
This design effort by Ripley is the best article I have ever seen on the internet for a Ham project. The thread has over 600 replies.

https://forums.qrz.com/index.php?threads/600-watt-hf-linear-amplifier-project.554685/

VE3TMT COMMENTS posted on the old Yahoo FT-990 User Group:
As you can see in the photo's section I had successfully mated the
FT990 to one of the DVB-T tuner dongles to provide a panadapter
display. Through my writings on different internet sites, I have been
getting a few emails asking how to do it.

Since this seems to be a good place to start, here are the
instructions to add the panadapter display to your FT990.

The IF tap in the FT-990 is made on the RF board, between T-1005 and
T-1010. This point is the output of the first IF mixer at 47.210 MHz,
before it goes to the filter. You want to tap before the filter to get
the broadest spectrum.

The tap is done through a 0.022 or 0.047 uf tatalum capacitor. When
you pull the RF board and pinpoint the location, you will see there is
a small trace that runs from T1005 to T1010, about 1/4" long. This is
the tap point. Right beside it there is suitable ground contact, after
scraping it to expose the copper. Put some electrical tape on the
board surrounding the trace before you solder the cap. This helps to
prevent shorts. You can then apply another layer of tape over the cap,
once the tap is complete.

I mounted an RCA jack on the rear of the radio between the DC power
connector and ground lug.   As a side note, I have a USB panel jack on
the way. My plans are to mount the dongle inside the radio, and simply
use a USB cord to connect to the computer, but that's another story.

This is the dongle I use:

http://www.ebay.com/itm/ Newsky-TV28T-v2-USB-DVB-T-RTL-
SDR-Receiver-RTL2832U-R820T- Tuner-MCX-Input-/160896092118?
pt=LH_DefaultDomain_0&hash= item25762787d6
http://www.ebay.com/itm/Newsky-TV28T-v2-USB-DVB-T-RTL-SDR-Receiver-RTL2832U-R820T-Tuner-MCX-Input-/160896092118?pt=LH_DefaultDomain_0&hash=item25762787d6>

it comes with a cheap antenna. Cut the coax off at the antenna end and
use the coax to tap in the radio and run to the RCA jack. The coax
comes up the RF board out the top and then you can snake it through
the middle of the radio (in front of the heat sink) to the underside.  
There is lots of room to work. Only tight quarters is on the RF board,
keep the cap and coax as flat as possible.

Ed


Pete Hill G4IOA
 

Hi Ed, thanks for the info on pan display for the FT-990.
I was thinking of tapping before the roofing filter to get a wider scope,
but I have read that the SDR dongle will then be open to all products from the first mixer.
I'm not sure if this would be a problem. I shall see.
Re the capacitor for tapping, I've been out of the hobby for a while, are tantilum caps made
at those values, 0.047uf? I seem to remember they were polarity sensitive.
Waiting for the PAT board from SDR Kits, this provides a high Z tap, so as not to degrade 
Rx performance and is already capacitor coupled.
Should be up and running this weekend.
Again thanks for the info.
73 Pete G4IOA