I recently obtained a Yaesu FTDX-400. I have operation and
service manuals but I can't find how to add bands.

--
There is something outrageous about such a huge body of evidence being
put together, then being confirmed in all kinds of other scientific
disciplines, particularly genetics, and having other people just sort
of deny it for reasons that have nothing to do with truth.
– Matthew Chapman, Darwin's great-great-grandson.

On Thu, 24 Jul 2014, Barry OGrady wrote:

I recently obtained a Yaesu FTDX-400. I have operation and
service manuals but I can't find how to add bands.

Well there are no diodes to clip on that baby, if that's what
you're asking.

You'll have to take out the bandswitch, put in a new one with more
positions, then add any needed coils and crystals for the new bands.

I'm assuming there is a crystal for each band, perhaps it's like the
Swan rigs where the bandswitch changed the VFO tuned circuit.

Of course, nobody is going to rip out the bandswitch.

So adding bands means changing the crystals (again assuming there are
crystals), swapping an existing band for a new band, or manually changing
crystals when you want to change band. If you're lucky, the tuned
circuits will cover more than the current bands, the moreso as you go up
in frequency. But if they can't cover the new bands, you'll have to
switch in some coils in parallel, to lower inductance if you want to move
the tuned circuits up in frequency, or add capacitance in parallel with
the tuned circuits to lower them in frequency. Maybe acceptable for adding
one band, too much trouble otherwise.

This rig dates from 1967. The bands had been more or less stable for some
time (well 11 metres was lost in the US and mostly lost in Canada in the
late fifties). That only changed in 1979 when the original WARC bands
were added. Some rigs did have auxiliary band positions, so you could
accomdate a new band. But for the most part, the old rigs stayed on the
old bands, while new rigs came along (now 35 years old) that could
accomodate the new bands. My TS-830 covers the WARC bands, it came out
just at the right time. But something a bit earlier likely lacked the
capability.

Then shortly after the WARC bands came into use, the rigs started
changing, no crystal for each band, it was all synthesized so the
potential for broader tuning was there. That's where the "clip
the diode" notion comes from, later rigs that could tune wider, but
had restricted tuning as they came from the factory. After a bit,
every new rig had a general coverage receiver, any control over
frequency coverage was about transmitting.

Michael

Barry OGrady wrote:
I recently obtained a Yaesu FTDX-400. I have operation and
service manuals but I can't find how to add bands.

Just looking over the manual for a minute, it looks like the band switch
selects one of eight crystal positions, and that output is beat with the
VFO and the modulated signal to form the output.

According to the manual, all eight positions are filled, and there are three
empty positions at the end. It looks like the trimmers are all in place if
the manual is any judge.

So, it looks to me like if you want to add bands, you would first need to
fill those three positions and set the trimmers.

The bandswitch also switches several other stages. You'll notice the last
three positions of S1e, S1f, and S1g are disconnected and you will have to
connect those to the appropriate points on the filter networks for the bands
you are using. But I suspect nothing would have to be added other than
jumpers.

It would be an interesting exercise.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

Michael Black wrote:
On Thu, 24 Jul 2014, Barry OGrady wrote:

I recently obtained a Yaesu FTDX-400. I have operation and
service manuals but I can't find how to add bands.

Well there are no diodes to clip on that baby, if that's what
you're asking.

You'll have to take out the bandswitch, put in a new one with more
positions, then add any needed coils and crystals for the new bands.

Look at the manual. The bandswitch, crystal holders and probably most
of the needed coils are already in place. It's mostly a matter of crystals
and either coils or adding jumpers to the existing coil networks.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

On Thu, 24 Jul 2014 00:50:28 -0400, Michael Black
wrote:

On Thu, 24 Jul 2014, Barry OGrady wrote:

I recently obtained a Yaesu FTDX-400. I have operation and
service manuals but I can't find how to add bands.

Well there are no diodes to clip on that baby, if that's what
you're asking.

You'll have to take out the bandswitch, put in a new one with more
positions, then add any needed coils and crystals for the new bands.

You probably thought it was a silly question but the FTDX-400
comes standard with the ability to add three 500Khz bands.

This rig dates from 1967. The bands had been more or less stable for some
time (well 11 metres was lost in the US and mostly lost in Canada in the
late fifties). That only changed in 1979 when the original WARC bands
were added. Some rigs did have auxiliary band positions, so you could
accomdate a new band. But for the most part, the old rigs stayed on the
old bands, while new rigs came along (now 35 years old) that could
accomodate the new bands. My TS-830 covers the WARC bands, it came out
just at the right time. But something a bit earlier likely lacked the
capability.

I do believe some WARC bands can be added to the FTDX-400 or could
be CB and so called freeband.

Then shortly after the WARC bands came into use, the rigs started
changing, no crystal for each band, it was all synthesized so the
potential for broader tuning was there. That's where the "clip
the diode" notion comes from, later rigs that could tune wider, but
had restricted tuning as they came from the factory. After a bit,
every new rig had a general coverage receiver, any control over
frequency coverage was about transmitting.

I was able to expand transmit and receive of my Yaesu FT-50 without
opening the case.

So I know my boatanchor can have three bands added but still don't
know how.

Michael

--
There is something outrageous about such a huge body of evidence being
put together, then being confirmed in all kinds of other scientific
disciplines, particularly genetics, and having other people just sort
of deny it for reasons that have nothing to do with truth.
– Matthew Chapman, Darwin's great-great-grandson.

On 24 Jul 2014 10:02:05 -0400, (Scott Dorsey) wrote:

Barry OGrady wrote:
I recently obtained a Yaesu FTDX-400. I have operation and
service manuals but I can't find how to add bands.

Just looking over the manual for a minute, it looks like the band switch
selects one of eight crystal positions, and that output is beat with the
VFO and the modulated signal to form the output.

According to the manual, all eight positions are filled, and there are three
empty positions at the end. It looks like the trimmers are all in place if
the manual is any judge.

So, it looks to me like if you want to add bands, you would first need to
fill those three positions and set the trimmers.

The bandswitch also switches several other stages. You'll notice the last
three positions of S1e, S1f, and S1g are disconnected and you will have to
connect those to the appropriate points on the filter networks for the bands
you are using. But I suspect nothing would have to be added other than
jumpers.

It would be an interesting exercise.

Perhaps not worthwhile.
It does have three empty crystal positions so logically I would need
to add the appropriate crystal for each band,
It does sound like I'm asking the impossible for such an old radio
but the facility is there.
Perhaps the information is on an amateur forum somewhere.

--scott

--
There is something outrageous about such a huge body of evidence being
put together, then being confirmed in all kinds of other scientific
disciplines, particularly genetics, and having other people just sort
of deny it for reasons that have nothing to do with truth.
– Matthew Chapman, Darwin's great-great-grandson.

Barry OGrady wrote:
On 24 Jul 2014 10:02:05 -0400, (Scott Dorsey) wrote:

The bandswitch also switches several other stages. You'll notice the last
three positions of S1e, S1f, and S1g are disconnected and you will have to
connect those to the appropriate points on the filter networks for the bands
you are using. But I suspect nothing would have to be added other than
jumpers.

It would be an interesting exercise.

Perhaps not worthwhile.

I think it would be very worthwhile, if only because 60M is so much fun.

It does have three empty crystal positions so logically I would need
to add the appropriate crystal for each band,
It does sound like I'm asking the impossible for such an old radio
but the facility is there.

I don't think it would be that bad. Start with 12M.... get a crystal from
ICM, they should know how to calculate it. Then wire the various sections
to use the 10M networks.

Likewise you could probably do 17M with the 15M networks without adding any
additional coils.

Doing 60 or 30 might mean you'd have to add some additional stuff and that
could take some tinkering.

Perhaps the information is on an amateur forum somewhere.

My guess is most of the people doing this are setting it up for 11M or the
various illicit freebands, and using the 10M networks. Doing that is
a good bit easier than adding 60M would be.
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."