http://groups.yahoo.com/group/FoxTango/
Question To Harry G3LLL
I have a question for you Harry. I recently ran into one of the
original G3LLL processor boards installed in one of the many FT-101s that
I own.
This rig is an FT-101EE.
It worked great when I got the rig and ran it for two years without a
hitch
as it was installed in the FT-101EE when I got it. I also used the rig
on 10 meter AM
with pretty good results.
I went to sell this rig off this past Friday evening last
weekend. Well the Rocket Scientist that I sold the rig to said the
rig didn't work right and had a bad hum in it yet it all worked perfectly
before I left his house and I talked to him all the way home.
By Monday he claimed to have tried putting a new 12BY7 driver
into the rig to get an increase in power on 10 meters. Yet there was
nothing wrong
with the valves / tubes. (What ever I say). I could tell he was pouting
and called
the rig a piece of crap and said he was going to junk the rig and part it
out.
I about had a cardiac and told him the deal was off anyway !! Cancelled
the
deal and got my rig back. Well so much for that part of the story.
After spending some time with my beloved FT-101EE, I found out
that something happened to the G3LLL processor and I really can't explain
why it went south. The rig had a nasty hum on the audio and practically
no RF output even when the processor was off.
I didn't have a diagram for this gem either. So I removed it
and put the EE back into stock condition all my power came back on the
rig
and the hum went away. I have no idea in heck what happened to the rig
in my
absence, but it's funny it worked flawlessly for the two years prior.
So now....... a few questions I have about the G3LLL processor.
I noticed the process was connected into the I.F. and when turned on had
greatly
increased the I.F. gain and overall noise level and receiver gain came up
on SSB
nicely. Yet when Yaesu made their processor board, they did not go this
route.
Yaesu's processor only worked on the transmit side (Tx I.F.) with no
receive gain
to be had. I'm assuming the G3LLL processor was correctly installed, so
was this the
intention of the designer to have increased I.F. gain on receive as well
?
I belive there was some chatter in the Fox Tango bulletin in the early
1970s
about just this subject and the receiver gain using the G3LL board.
Also then I noticed when I got the rig back and after I pulled the
processor
out of circuit completely putting the FT-101EE back into stock
condition. I also put my AM filter back into the unit, and
now AM was working better then ever and never sounded so good on the rig.
It never occurred to me prior because I thought the rig was working well
and
I never had to do any repairs on the transceiver for two years prior
until this
recent trade (deal) went sour.
Thinking about it later and I had often wondered about it too over the
past couple of years.
Having noted that the G3LLL processor was in the receiver I.F. as well as
transmitter
I.F. that means the XF-30 crystal filter installed on the processor board
all this time
past was limiting my receive I.F. thus rendering my AM filter 6khz
response making
it some what worthless in the past.
Bottom line here it would have had to have been a combination of fate
that this
rig had the G3LLL processor in the receive I.F. and thus my having put in
the AM
filter because I like to run AM now and again. Thus having the problem
of the
limited I.F. response from the processor filter.
Assuming I've made some sense here.
Harry, can you tell us something about speech processing. I know you
were
a major mover and shaker in this filed in the early 1970s before Yaesu
ever dreamed of putting speech processing in their rigs. Also maybe you
can tell us a little as to why the process was installed into the receive
I.F.
giving more I.F. gain. While at the same time limiting the I.F. to the
filters 2.8 Khz and thus also limiting the ability of the rig to run
AM properly on receive. Did this ever come up in years past ??
Regards
Carol Maher
W4CLM
Certifiedtified Electronics
http://groups.yahoo.com/group/FoxTango/
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