Question : Is the Ten-Tec 6m transverter also available for 28 MHz e.g.
RX : 50 -- 28 MHz ; TX : 28 --- 50 MHz
or can the 14 to 50 MHz transverter be readily modified for operation
from a 28 MHz base unit ?

Reason for the above question : I have an old (but almost unused) Yaesu
FT901DM HF transceiver with a FTV901R transverter with 2m and 70cms
modules but without a 6 m module.
The system works through the HF transceiver's 28 - 30 MHz band . In
Europe the 6m band is from 50 - 52 MHz.

The 20 to 6 meter converter is made to operate in the low end of 6 meters.
The US band is 50 to 54 mhz but TT does not recommend operating much above
52 mhz with their transverter.
They do make a 2 meter to 6 meter transverter so you could run you equipment
and feed it to the trtansverter to get on 6 that way.

Converting from 10 meters to 6 meters is not done very often as it is
difficult to keep the 2nd harmonic of 10 meters out of the 6 meter output.
By changing crystals and a few tuned circuits I don;t see why you could not
make the converter work with a 10 meter rig. It might be difficult to
filter out the 10 meter signal.

Go here and look at their products.

http://www.tentec.com/

I was having trouble reducing the lowband rig output to 5 to 10 watts needed
by the transverter. I finally designed a hard keying circuit and also
bypassed part of the transverter padding and fed the low level (milliwat)
signal into the transverter. It worked fine by doing that and no worries
about blowing out the backend of the transverter.

73 de ku4pt