The AM Forum

Hi to all:

I have a Yaesu FT-101FX.  The manual states there is an optional cw filter that can be added.

I did not see any additional information on adding an AM filter.  At present AM sounds bad.  It is being restricted.  

(1)  How many "drop in" filters can this radio hold at one time, Am, SSB and CW?

(2)  I know I can add the CW filter but can I also add an AM filter?  I am going to go over the schematic but it is packed away.    

I see International Radio sells a 6000 Hz AM filter, SSB filters and CW filters.

Just a note.  The previous owner replaced the original SSB filter with a more narrow SSB filter.  I have to open up the radio to find out which SSB filter is installed.

(3)  Are these filters really drop in or are they soldered in?

Thank you,

Chuck

If the 101FX is the same as the rest of the 101 series, I think there's spots on the filter board for all 3 optional filters (CW, SSB, AM). It's been a while since I've had one open.

Hey Chuck,

  Not sure about your rig variant, however the older ones
FT-101B,D etc the guys would remove the CW filter, and
with a few diodes on the mode Switch you could put an
AM filter in it's place.

   I "Added" an AM filter to a 101B with a simple perf board
thing and double side taped it in there. This retained SSB
and CW and added AM. Still gotta play with the diodes on
the mode switch but since you have to do that anyway
it's not that big of a deal. The instructions are on the web
and come with the Fox Tango filter my cust. had obtained.

   Original filters plug in but have nuts on the case to hold
them in place. It worked real nice. I think they only hold
2 filters max.

/Dan

KB3OUK and Dan,

Thank you for your input.  Dan, thank you for the pictures.  

Any body else have and input?

Chuck

Chuck,

As the others have pointed out there are only two slots assigned to the SSB and optional CW filter.  You could either modify to add AM filter in place of CW (or give up SSB and use AM filter in its place) or build an additional holder board.

The FR-101 also uses the same filter series in case you come across a parts unit FR-101, most that I have seen came with the AM filter.

I believe the FX was the very last of the FT-101 series and was the stripped down model that made many things optional (like the speech processor, DC converter, etc.)  It is likely the CW slot is currently open on yours and in that case the diode mod described earlier would be the easiest.

Of course you could just interconnect another receiver with your FT-101FX to  provide quality AM reception.  The ANT jack will feed an auxiliary receiver through the main coax connection and a grounded during receive mode contact through the accessory jack will take care of standby switching for most modern receivers.

I always thought that was just to hook up a second receive-only antenna, but now that I think about it, it would work either way.

In the FT-101 series it is a simple circuit with a relay that disconnects the extra port during transmit and puts it in parallel with the main port on receive.  Later Yaesu transceivers used a little more complex circuit that provided more options better suited to support both receive only antennas and external receivers.

For what it is worth, the FT-101 "fuse lamp" isn't in line with the auxiliary antenna port although I doubt if it provides much protection in any case.

I ended up with an extra FR-100B receiver that is paired with my FT-101.

KB3OUK, Roger and all,

I see on the back of the radio, just left of the coax input, there is a RCA jack labeled Receiver Ant.  
Above the receiver antenna RCA plug is the lamp fuse.

I believe I hook up the extra receiver to this "Receiver Ant" RCA plug.

Thank you.

Chuck

Neat rig.  Thats the economy version of the FT 101F.    The AM filter install is the same as the rest of the 101 line. You can remove the CW filter, Install the AM filter in its place, then modify the mod switch.  Its pretty simple.

Here are the instructions:

http://foxtango.org/ft101/foxtangoft101misc.htm

kE7TRP,

Thank you for the Fox Tango link.

Chuck