Drake R8 question
 

Pete KE9OA wrote:

I may be picking up one of these things tomorrow. Looking at the input
bandpass filter schematic, I notice a T type of attenuator that consists of
two 270 ohm series resistors, with a 330 ohm shunt resistor on the MW filter
section.
Am I dreaming, or did Drake really dumb down the design with a full time
attenuator on the MW band? If this is the case, it looks like I have yet
another project.

Pete

I don't see that attenuator on the MW (0.5-1.5-Mhz) bandpass filter for
the R8'B'. The MW bandpass circuit on the 'B' looks like all the other
bands but with different component values of course.

Drake R8 question
 

That sounds good.............the service manual I have is for the R8E, so
they may have installed an attenuator on that model. I will give Drake a
call this morning.

Pete

"Drakefan" wrote in message
news:Fluxj.7931$xg6.6122@trnddc07...
Pete KE9OA wrote:

I may be picking up one of these things tomorrow. Looking at the input
bandpass filter schematic, I notice a T type of attenuator that consists
of two 270 ohm series resistors, with a 330 ohm shunt resistor on the MW
filter section.
Am I dreaming, or did Drake really dumb down the design with a full time
attenuator on the MW band? If this is the case, it looks like I have yet
another project.

Pete

I don't see that attenuator on the MW (0.5-1.5-Mhz) bandpass filter for
the R8'B'. The MW bandpass circuit on the 'B' looks like all the other
bands but with different component values of course.

Drake R8 question
 

Pete KE9OA wrote:

That sounds good.............the service manual I have is for the R8E, so
they may have installed an attenuator on that model. I will give Drake a
call this morning.

I get the same S meter readings on the R8, R8A and R8B. The attenuator can be
kicked in on all three, difference being is that the pre-amp can be used in the
A & B but not on the R8.

Drake R8 question
 

Drakefan wrote:
Pete KE9OA wrote:

I may be picking up one of these things tomorrow. Looking at the input
bandpass filter schematic, I notice a T type of attenuator that
consists of two 270 ohm series resistors, with a 330 ohm shunt
resistor on the MW filter section.
Am I dreaming, or did Drake really dumb down the design with a full
time attenuator on the MW band? If this is the case, it looks like I
have yet another project.

Pete

I don't see that attenuator on the MW (0.5-1.5-Mhz) bandpass filter for
the R8'B'. The MW bandpass circuit on the 'B' looks like all the other
bands but with different component values of course.

Different first mixer?

Drake R8 question
 

No, it is using the same 1st mixer. In my service manual for the R8E, right
after the input switching diode for the MW range, I see the attenuator. I
just talked to Bill Frost, over at Drake, and he tells me that all of the
front ends are the same. If this is the case, it shouldn't be too hard to
remove it. They may have pulled a tricky one, the JRC did with the MW range
on the
NRD-515.
On another note, I have built the first engineering prototype of the new
Palstar active loop antenna. There was a bit of a delay receiving the
ferrite rod stock, but that should be coming in, in the next few days or
so.
I still need a few PCB footprint files.........after this, I will be able to
do the board layout. It shouldn't take more than a few hours to do.

Pete

"dave" wrote in message
...
Drakefan wrote:
Pete KE9OA wrote:

I may be picking up one of these things tomorrow. Looking at the input
bandpass filter schematic, I notice a T type of attenuator that consists
of two 270 ohm series resistors, with a 330 ohm shunt resistor on the MW
filter section.
Am I dreaming, or did Drake really dumb down the design with a full time
attenuator on the MW band? If this is the case, it looks like I have yet
another project.

Pete

I don't see that attenuator on the MW (0.5-1.5-Mhz) bandpass filter for
the R8'B'. The MW bandpass circuit on the 'B' looks like all the other
bands but with different component values of course.

Different first mixer?

Drake R8 question
 

Thanks Steve............I appreciate that. Years ago, when I was living in
Cedar Rapids, there was a fellow named Steve in Michigan that had some sort
of intermod problem with a Sony 6800W. Were you that person, or was it
another Steve?

Pete

"dxAce" wrote in message
...


Pete KE9OA wrote:

That sounds good.............the service manual I have is for the R8E, so
they may have installed an attenuator on that model. I will give Drake a
call this morning.

I get the same S meter readings on the R8, R8A and R8B. The attenuator can
be
kicked in on all three, difference being is that the pre-amp can be used
in the
A & B but not on the R8.

Drake R8 question
 

Pete KE9OA wrote:

Thanks Steve............I appreciate that. Years ago, when I was living in
Cedar Rapids, there was a fellow named Steve in Michigan that had some sort
of intermod problem with a Sony 6800W. Were you that person, or was it
another Steve?

Not me Pete, I've never had a 6800W.

Drake R8 question
 

Thanks Steve,

I am going to take a look at that R8 in a little while and see how it works.
My friend is also bring over an R7 S/N 3400 range, with a PLL unlock
problem. Just what I always wanted to work on...........another one!

Pete

"dxAce" wrote in message
...


Pete KE9OA wrote:

Thanks Steve............I appreciate that. Years ago, when I was living
in
Cedar Rapids, there was a fellow named Steve in Michigan that had some
sort
of intermod problem with a Sony 6800W. Were you that person, or was it
another Steve?

Not me Pete, I've never had a 6800W.

Drake R8 question
 

U bet you............I've got it apart right
now......................cleaning the contacts on the regulator board got
the low end of the low band VCO working....................the high band VCO
only works up at MHz. I am thinking, that with the high S/N, it looks like
the owner of this radio sold the R7A face plate to somebody and installed an
R7 faceplate on this radio before he moved it out.
I played a little bit with the R8...........now I see why everybody likes it
so much. I think I will modify it so the preamp works on all ranges, that
is, after I remove that pesky MW attenuator. Nice receivers.

Pete

"dxAce" wrote in message
...


Pete KE9OA wrote:

Thanks Steve,

I am going to take a look at that R8 in a little while and see how it
works.
My friend is also bring over an R7 S/N 3400 range, with a PLL unlock
problem. Just what I always wanted to work on...........another one!

Keep those R7's running.

Drake R8 question
 

Pete KE9OA wrote:

U bet you............I've got it apart right
now......................cleaning the contacts on the regulator board got
the low end of the low band VCO working....................the high band VCO
only works up at MHz. I am thinking, that with the high S/N, it looks like
the owner of this radio sold the R7A face plate to somebody and installed an
R7 faceplate on this radio before he moved it out.
I played a little bit with the R8...........now I see why everybody likes it
so much. I think I will modify it so the preamp works on all ranges, that
is, after I remove that pesky MW attenuator. Nice receivers.

I just saw a message on the Drake reflector wondering about a possible change
due to the serial number. Thought it must be an R7A vs. an R7.

Name Dan, by any chance?

Drake R8 question
 

Pete KE9OA wrote:

No, it is using the same 1st mixer. In my service manual for the R8E, right
after the input switching diode for the MW range, I see the attenuator. I
just talked to Bill Frost, over at Drake, and he tells me that all of the
front ends are the same. If this is the case, it shouldn't be too hard to
remove it. They may have pulled a tricky one, the JRC did with the MW range
on the
NRD-515.

They must all be the same *except* for the 'E' model. I can see why they
might have wanted to attenuate the MW band in a receiver made for use in
Europe where the MW signals can be very high at times. Have you actually
confirmed that your model has the MW attenuator?

Drake R8 question
 

In article , Pete KE9OA
wrote:

U bet you............I've got it apart right
now......................cleaning the contacts on the regulator board got
the low end of the low band VCO working....................the high band VCO
only works up at MHz. I am thinking, that with the high S/N, it looks like
the owner of this radio sold the R7A face plate to somebody and installed an
R7 faceplate on this radio before he moved it out.
I played a little bit with the R8...........now I see why everybody likes it
so much. I think I will modify it so the preamp works on all ranges,

If you do this mod, would you post a how-to? I have an R8; I would like
to make the pre-amp work on LW NDBs.

thanks,
-j

that
is, after I remove that pesky MW attenuator. Nice receivers.

Pete

"dxAce" wrote in message
...


Pete KE9OA wrote:

Thanks Steve,

I am going to take a look at that R8 in a little while and see how it
works.
My friend is also bring over an R7 S/N 3400 range, with a PLL unlock
problem. Just what I always wanted to work on...........another one!

Keep those R7's running.

Drake R8 question
 

How did you guess????????????????????????? He's the guy!

Pete

"dxAce" wrote in message
...


Pete KE9OA wrote:

U bet you............I've got it apart right
now......................cleaning the contacts on the regulator board got
the low end of the low band VCO working....................the high band
VCO
only works up at MHz. I am thinking, that with the high S/N, it looks
like
the owner of this radio sold the R7A face plate to somebody and installed
an
R7 faceplate on this radio before he moved it out.
I played a little bit with the R8...........now I see why everybody likes
it
so much. I think I will modify it so the preamp works on all ranges, that
is, after I remove that pesky MW attenuator. Nice receivers.

I just saw a message on the Drake reflector wondering about a possible
change
due to the serial number. Thought it must be an R7A vs. an R7.

Name Dan, by any chance?

Drake R8 question
 

I sure will. Probably won't get to it for a few days. Right now, I am
fighting the flu AND fixing that R7

Pete

"JoanD'arcRoast" wrote in message
. ..
In article , Pete KE9OA
wrote:

U bet you............I've got it apart right
now......................cleaning the contacts on the regulator board got
the low end of the low band VCO working....................the high band
VCO
only works up at MHz. I am thinking, that with the high S/N, it looks
like
the owner of this radio sold the R7A face plate to somebody and installed
an
R7 faceplate on this radio before he moved it out.
I played a little bit with the R8...........now I see why everybody likes
it
so much. I think I will modify it so the preamp works on all ranges,

If you do this mod, would you post a how-to? I have an R8; I would like
to make the pre-amp work on LW NDBs.

thanks,
-j

that
is, after I remove that pesky MW attenuator. Nice receivers.

Pete

"dxAce" wrote in message
...


Pete KE9OA wrote:

Thanks Steve,

I am going to take a look at that R8 in a little while and see how it
works.
My friend is also bring over an R7 S/N 3400 range, with a PLL unlock
problem. Just what I always wanted to work on...........another one!

Keep those R7's running.

Drake R8 question
 

Pete KE9OA wrote:

How did you guess?????????????????????????

They don't call me 'Ace' for nothing!

He's the guy!

Pete

"dxAce" wrote in message
...


Pete KE9OA wrote:

U bet you............I've got it apart right
now......................cleaning the contacts on the regulator board got
the low end of the low band VCO working....................the high band
VCO
only works up at MHz. I am thinking, that with the high S/N, it looks
like
the owner of this radio sold the R7A face plate to somebody and installed
an
R7 faceplate on this radio before he moved it out.
I played a little bit with the R8...........now I see why everybody likes
it
so much. I think I will modify it so the preamp works on all ranges, that
is, after I remove that pesky MW attenuator. Nice receivers.

I just saw a message on the Drake reflector wondering about a possible
change
due to the serial number. Thought it must be an R7A vs. an R7.

Name Dan, by any chance?

Drake R8 question
 

m II wrote:

dxAcehole, pathological liar, racist and common drunk,
during his fifth annual Farewell Forever tour, said:

They don't call me 'Ace' for nothing!

You are an arrogant, self titled non entity.

Yeah, and you're just another dumbass Canuck!

Go blow 'Eduardo', boy.

Drake R8 question
 

I found the location of the MW attenuator.......................it appears
that I will have to change the 150pF shunt cap at the filter input to 220pF,
to make the filter symmetrical. This is for the R8.
As far as the R7, the 25V power supply line for the tune voltage was only
7V. This is the reason the receiver only locks on the low ranges. Unless the
power supply board has gone through some sort of revision, somebody replaced
the 78L24 regulator with an LM317Z. The 78L24 is a low current 24V positive
regulator, while the 317 is an adjustable regulator. Totally different
pin-out from the original, and it would never work in this circuit.
Basically, there is a multivibrator circuit that provides 35VAC. This
voltage is full-wave rectified with a bridge consisting of r 1N4148s,
filtered, and applied to the 24V regulator.
I should be able to get it running, once I get the correct part.

Pete

"dxAce" wrote in message
...


Pete KE9OA wrote:

How did you guess?????????????????????????

They don't call me 'Ace' for nothing!

He's the guy!

Pete

"dxAce" wrote in message
...


Pete KE9OA wrote:

U bet you............I've got it apart right
now......................cleaning the contacts on the regulator board
got
the low end of the low band VCO working....................the high
band
VCO
only works up at MHz. I am thinking, that with the high S/N, it looks
like
the owner of this radio sold the R7A face plate to somebody and
installed
an
R7 faceplate on this radio before he moved it out.
I played a little bit with the R8...........now I see why everybody
likes
it
so much. I think I will modify it so the preamp works on all ranges,
that
is, after I remove that pesky MW attenuator. Nice receivers.

I just saw a message on the Drake reflector wondering about a possible
change
due to the serial number. Thought it must be an R7A vs. an R7.

Name Dan, by any chance?

Drake R8 question
 

I checked the sensitivity of the R8 at the MW band edges vs the adjacent
ranges. No difference in sensitivity over the whole tuning range. 10uV RF
input gives S6 meter reading, indicating that there is no MW attenuator in
the non-European version. Good news.............not I don't have to tear
into it until I figure out the preamp enable mod for the LW/MW ranges.

Pete

"Pete KE9OA" wrote in message
. ..
I sure will. Probably won't get to it for a few days. Right now, I am
fighting the flu AND fixing that R7

Pete

"JoanD'arcRoast" wrote in message
. ..
In article , Pete KE9OA
wrote:

U bet you............I've got it apart right
now......................cleaning the contacts on the regulator board
got
the low end of the low band VCO working....................the high band
VCO
only works up at MHz. I am thinking, that with the high S/N, it looks
like
the owner of this radio sold the R7A face plate to somebody and
installed an
R7 faceplate on this radio before he moved it out.
I played a little bit with the R8...........now I see why everybody
likes it
so much. I think I will modify it so the preamp works on all ranges,

If you do this mod, would you post a how-to? I have an R8; I would like
to make the pre-amp work on LW NDBs.

thanks,
-j

that
is, after I remove that pesky MW attenuator. Nice receivers.

Pete

"dxAce" wrote in message
...


Pete KE9OA wrote:

Thanks Steve,

I am going to take a look at that R8 in a little while and see how it
works.
My friend is also bring over an R7 S/N 3400 range, with a PLL unlock
problem. Just what I always wanted to work on...........another one!

Keep those R7's running.