Re: VE3EFJ third mixer mod for the R4C
My AMP-4 feedback loop was designed for about a 3 dB roll-off at 3 kHz. Personal choice. Rob, NC0B
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On Jan 1, 2025, at 10:10?AM, Jim Shorney via groups.io <jimNU0C@...> wrote:
?
Yeah, that works. The TDA chips are rock stable and practically bulletproof when implemented properly. I have one of the Velleman TDA2002 modules that I acquired some years back for my R4C, I just have not got a round tuit yet. One thing that I did do was to alter the capacitance in the feedback network to roll the audio off around 4KHz.
On Wed, 01 Jan 2025 08:33:53 -0800
"Gary WB6OGD via groups.io" <winbladgary@...> wrote:
It's a waste of time and money to design an AF amp for the Drake.
I used a (now) 75cent complete TDA2030 module from china.
Like this one:
--
73
-Jim
NU0C
|
Jim maybe this will help. I touched up several solder joints although they didn¡¯t look good but not cracked. I switched the input to the counter and it is reading 17 to 18 mhz as the frequency is jumping around so is not locked. I wonder if that is a clue??
Jim VE1RB
Good ideas Jim and I will get at doing that today. It is windy and raining here quite hard. A good job inside hi hi. I will let you know how it goes. Many thanks for the suggestions?and help.
Jim VE1RB
At this point I am suspicious of that 1.3 MHz reading. That may be a spurious reading. It seems to me that the VCO should not be able to run there. What is the level of the signal? The frequency determining components are L502 and the varactor diodes. Resist the temptation to try to adjust L502. As a long time tech told me back in the dim past, when you have a failure "it is never the alignment".
At this point I think I would inspect the solder connections in the high VCO circuit under magnification and good lighting. You could have a failed joint or via. Check the voltages on the three JFETs. C156 or C517 could be suspect. You have a working low VCO to compare voltage and resistance readings to.
On Wed, 1 Jan 2025 07:41:18 -0400
"Jim Harris via " <radiove1rb=[email protected]> wrote:
> Yes Gary I did the ground on RFC505? when looking at the frequency on
> the counter and it does drop a lot. So I guess you are saying the High
> VCO is oscillating at 1.3 MHz . If that is the case there must be
> something wrong on that board unless the info it gets is wrong. Hope
> this helps.
--
73
-Jim
NU0C
|
All the talk about the audio amplifier on an R-4C intrigues me to ask the question, ¡°What are you doing about the speaker?¡± ? With a 50 year old speaker in some cases, what are you replacing it with, without doing any mechanical work?¡± ??
? ? ?Frank Krozel ? ? ? ? ? ?KG9H Life Member, ARRL ? ? (630) 924-1600 kg9hfrank@...
|
Re: AF AMP VE3EFJ third mixer mod for the R4C
Gary!!! Bravo! I too used a device like that for mine( TDA7377)... I removed the original jensen speaker, used a lower efficiency driver, yet one with better listening specs. My MS-4 has been modified into a more practical speaker enclosure also. I tossed the cardboard speaker escutcheon and made a proper one out of hardwood ply. Lots of other things to make the box have more decent response also... Those TDA modules are great! I get about 10-11 watts from mine. 2.5 watts does not cut it when guys are now hell bent on 2.8kHz bandwidth or more. Doing all this and using one of Franks 2.8 filters was very liberating. I thought about using in bridged mode, yet 10-11 watts is flat enough.
On Wednesday, January 1, 2025 at 11:33:55 AM EST, Gary WB6OGD via groups.io <winbladgary@...> wrote:
It's a waste of time and money to design an AF amp for the Drake.
I used a (now) 75cent complete TDA2030 module from china.
?
Like this one:
https://www.ebay.com/itm/314750105717?_skw=TDa2030+amplifier+module&itmmeta=01JGHB55413WV2745A8XBJYQBN&hash=item4948917875:g:upwAAOSwiFZky38Y&itmprp=enc%3AAQAJAAAA8HoV3kP08IDx%2BKZ9MfhVJKl9LzhQlEV7hr7qISFGACsJ4nRv905MP85TlwPdXY5R6c3VMsAxJIQKAv5Wui8d0Yi5pi9YIYuzUCSjP5ml2suXZumYP9VjoXxEuLgFUi%2FbDTCLNL%2Bfzq1996uV4tf62yNmyWpQMXYoXUZz8Vv9amSvPAB9B%2B0dDCc1DrezcMlCO9tR6%2FQCZNyVOKUH0VaPBtchCvaYlnLrPBcthdKwTS0tsusftmUTkrWDt3q1FPcmtYKvA7qfjd%2FramvBIYhkHsdzm2t9cFMXaqQoBKG16X7Bgfc83okBCT8p2OAuM1pXVw%3D%3D%7Ctkp%3ABk9SR57SlKuEZQ
?
See my Folder in the Files section:
? ? "Drake R4A or R4B solid state AF Amp"
?
73,
Gary
WB6OGD
?
|
Re: VE3EFJ third mixer mod for the R4C
I've seen that board on Osh Park. I like the purple one. :D On Wed, 01 Jan 2025 09:02:55 -0800 "Paul Christensen via groups.io" <w9ac@...> wrote: The image below shows a discrete class AB amp layout meant specifically for the Drake R4 series -- 73 -Jim NU0C
|
Re: VE3EFJ third mixer mod for the R4C
Yeah, that works. The TDA chips are rock stable and practically bulletproof when implemented properly. I have one of the Velleman TDA2002 modules that I acquired some years back for my R4C, I just have not got a round tuit yet. One thing that I did do was to alter the capacitance in the feedback network to roll the audio off around 4KHz. On Wed, 01 Jan 2025 08:33:53 -0800 "Gary WB6OGD via groups.io" <winbladgary@...> wrote: It's a waste of time and money to design an AF amp for the Drake.
I used a (now) 75cent complete TDA2030 module from china.
Like this one:
-- 73 -Jim NU0C
|
Re: VE3EFJ third mixer mod for the R4C
On Wed, Jan 1, 2025 at 08:33 AM, Gary WB6OGD wrote:
It's a waste of time and money to design an AF amp for the Drake.
I used a (now) 75cent complete TDA2030 module from china.
?
The TDA series and LM380 are fine although I wanted lower noise with no detectable hiss at any setting of the AF control when using studio-grade headphones.?
?
The image below shows a discrete class AB amp layout meant specifically for the Drake R4 series.? It has on-board V regulation, PS decoupling, and two isolated analog ground planes that meet together at the at the V reg ground pin.? Loudspeaker current can't modulate the ground reference of the high-gain, low-noise front-end stage.?
?
The high-gain stage uses low-noise Toshiba transistors. The output cap is 4500 uF.? An additional regulated output can feed the PTO.? ? Sure, it's only communications-grade audio but anyone wishing to listen at my QTH, you're welcome to stop by and hear the difference.
?
Paul, W9AC
?
?
?
|
Good ideas Jim and I will get at doing that today. It is windy and raining here quite hard. A good job inside hi hi. I will let you know how it goes. Many thanks for the suggestions?and help.
Jim VE1RB
At this point I am suspicious of that 1.3 MHz reading. That may be a spurious reading. It seems to me that the VCO should not be able to run there. What is the level of the signal? The frequency determining components are L502 and the varactor diodes. Resist the temptation to try to adjust L502. As a long time tech told me back in the dim past, when you have a failure "it is never the alignment".
At this point I think I would inspect the solder connections in the high VCO circuit under magnification and good lighting. You could have a failed joint or via. Check the voltages on the three JFETs. C156 or C517 could be suspect. You have a working low VCO to compare voltage and resistance readings to.
On Wed, 1 Jan 2025 07:41:18 -0400
"Jim Harris via " <radiove1rb=[email protected]> wrote:
> Yes Gary I did the ground on RFC505? when looking at the frequency on
> the counter and it does drop a lot. So I guess you are saying the High
> VCO is oscillating at 1.3 MHz . If that is the case there must be
> something wrong on that board unless the info it gets is wrong. Hope
> this helps.
--
73
-Jim
NU0C
|
Re: VE3EFJ third mixer mod for the R4C
It's a waste of time and money to design an AF amp for the Drake.
I used a (now) 75cent complete TDA2030 module from china.
?
Like this one:
https://www.ebay.com/itm/314750105717?_skw=TDa2030+amplifier+module&itmmeta=01JGHB55413WV2745A8XBJYQBN&hash=item4948917875:g:upwAAOSwiFZky38Y&itmprp=enc%3AAQAJAAAA8HoV3kP08IDx%2BKZ9MfhVJKl9LzhQlEV7hr7qISFGACsJ4nRv905MP85TlwPdXY5R6c3VMsAxJIQKAv5Wui8d0Yi5pi9YIYuzUCSjP5ml2suXZumYP9VjoXxEuLgFUi%2FbDTCLNL%2Bfzq1996uV4tf62yNmyWpQMXYoXUZz8Vv9amSvPAB9B%2B0dDCc1DrezcMlCO9tR6%2FQCZNyVOKUH0VaPBtchCvaYlnLrPBcthdKwTS0tsusftmUTkrWDt3q1FPcmtYKvA7qfjd%2FramvBIYhkHsdzm2t9cFMXaqQoBKG16X7Bgfc83okBCT8p2OAuM1pXVw%3D%3D%7Ctkp%3ABk9SR57SlKuEZQ
?
See my Folder in the Files section:
? ? "Drake R4A or R4B solid state AF Amp"
?
73,
Gary
WB6OGD
?
|
At this point I am suspicious of that 1.3 MHz reading. That may be a spurious reading. It seems to me that the VCO should not be able to run there. What is the level of the signal? The frequency determining components are L502 and the varactor diodes. Resist the temptation to try to adjust L502. As a long time tech told me back in the dim past, when you have a failure "it is never the alignment". At this point I think I would inspect the solder connections in the high VCO circuit under magnification and good lighting. You could have a failed joint or via. Check the voltages on the three JFETs. C156 or C517 could be suspect. You have a working low VCO to compare voltage and resistance readings to. On Wed, 1 Jan 2025 07:41:18 -0400 "Jim Harris via groups.io" <radiove1rb@...> wrote: Yes Gary I did the ground on RFC505? when looking at the frequency on
the counter and it does drop a lot. So I guess you are saying the High
VCO is oscillating at 1.3 MHz . If that is the case there must be
something wrong on that board unless the info it gets is wrong. Hope
this helps. -- 73 -Jim NU0C
|
Re: VE3EFJ third mixer mod for the R4C
FWIW the TR7 uses an LM380. It works pretty well. On Wed, 1 Jan 2025 10:45:24 -0500 "Mike Bryce via groups.io" <prosolar@...> wrote: FYI¡ I designed an audio amp board for the R4C that used a LM380. Worked great and had plenty of humph to drive the MS4 speaker to room filling volume -- 73 -Jim NU0C
|
Re: VE3EFJ third mixer mod for the R4C
Rob,
There¡¯s always the possibility of starting over, making the changes to the artwork as necessary to use newer parts and or different parts with different footprints.
I have time to do a few¡ provided I have the physical dimensions for the board and of course schematics.
FYI¡ I designed an audio amp board for the R4C that used a LM380. Worked great and had plenty of humph to drive the MS4 speaker to room filling volume
Mike, WB8VGE
SunLight Energy Systems
The Heathkit Shop
.com/
J e e p
o|||||||o?
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On Dec 31, 2024, at 5:02 PM, Rob Sherwood via < rob@...> wrote:
Hi Glenn, ? In 2022 there was an attempt to have Harbach Electronics offer the boards and a parts kit.? My old Gerber files were not readable by most current PCB programs.? A ham in Germany was able to get my old Gerber files converted to current formats.? By the time that problem was solved Harbach had lost interest.? I just sent an email to Dieter asking if he could locate the updated Gerber files and send them to me.? If this can be accomplished I would be happy to turn them over to anyone who was interested in running another batch of boards.? Call me if you want to chat. ? Rob, NC0B 303-995-2749 cell ? ? ?
|
Using a doubler off the fil line has been done before.? ?We used a doubler (FWD) and used the 5.0 vac fil on the drake L4B fil xfmr sec winding....to obtain? 12.74 vdc (after V drop from? both diodes).? ?That was used to operate the primary? side of an opto isolator. Sec output side of the same opto was used to key a mess of sped up vac relays. IE: the opto was used for a soft key setup.? That was a cheap and easy way to obtain 12.74 vdc.? The opto required anything from 9-18 vdc ( nominal was 15 vdc).?
On paper, it should work with a 6.3 vac fil......= 16.41vdc (including V drop from both diodes)? and your proposed LM380.? ?( LM380 requires? 10-22 vdc).? Suitable filtering may just require the? 2 x caps in the doubler.? Perhaps bigger value caps.? An extra? filter on the output would also work, like a simple C-R-C? added on....... provided the v drop across the R? was not too great.? ?A? C-L-C? also works good.?
|
Yes Gary I did the ground on RFC505? when looking at the
frequency on the counter and it does drop a lot. So I guess you
are saying the High VCO is oscillating at 1.3 MHz . If that is the
case there must be something wrong on that board unless the info
it gets is wrong. Hope this helps.
73, Jim VE1RB
On 2024-12-31 18:06, Gary Follett via
groups.io wrote:
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I don¡¯t know how it can read 1.3 MHz if not oscillating¡
Yes, the lo band VCO should change frequency if you pill
RFC502 to ground, pulling the varactor drive from ~21 volts to
zero volts.
Gary
W0DVN
Do
you mean on the low VCO will drop as I don¡¯t think the
high VCO is oscillating as it reads 1.3 mhz and dies not
change when I put a ground on RFC 505. Also those
voltages on the test pint do not change when the I
change from the low VCO to the high one. I will test
again.?
Jim
VE1RB
On Tue, Dec 31, 2024
at 3:33?PM Gary Follett via ??<xntrick1948= [email protected]>
wrote:
Those
voltages will inly read correctly if the PLL loop
is closed. Do you have enough extenders to put the
radio into operating condition?
The way you have it operating, the output at
the test point is simply ramping up to the
maximum that can be produced by U504 in an open
loop condition.
However, the high band VCO should also go
high in frequency with ~21 volts on RFC505.
I assume that, if you short RFC502 (lo band
VCO) to ground, the frequency you read drops
from the 65 MHz quite a lot.
Gary
W0DVN?
Hi Gary, I did the ground on RFC505
and no change except that the voltage
goes very low of course going through
a 100K resistor. The frequency counter
shows 1.3 MHz on the output of the VCO
when it is on 10 or 15 meters. When I
switch to 14 MHz it pops up to 65 MHz
but it is not connect to the
translator board just plugged into my
extenders.? I did a voltage check at
the test point off of CR515, CR516,
CR517, and CR518 and here is what I
got, Way off.
1.5 MHZ 21.24 VDC Looks like it
should be 3 volts. the photocopy is
heard to read.
14.0 MHz 21.20 VDC Looks like it
should be maybe 15 volts
21.0 MHZ 21.17 VDC and looks like it
should be 6 Volts
29.5 MHZ 21.15 VDC and looks like it
should be 14.5 volts
Maybe I am way off Gary but hope that
maybe that helps. Almost looks like
something it shorted? I don't know
where to go next so any help
appreciated. Thanks.
73, Jim VE1RB
On 2024-12-30 13:42, Gary Follett
via??wrote:
That is WAY too
high!!
The maximum that should be seen
at this point is ~15 volts, the high
end of 10 meters. 20 volts here
would push the VCO to its maximum
frequency, if it is running at all.?
Is there any RF signal coming out
of the VCO? You may have answered
this previously but I seem to have
forgotten the answer. If there IS
RF, here, what is its frequency?
Something is telling the PLL
phase detector to put out a voltage
thinking that the frequency is too
low, which is why the voltage on
RFC505 is so high.
Can you short RFC505 cold end to
ground? This SHOULD make the VCO, if
it is operating, go to the low end
of its range in frequency. This
point is fed via a 100K resistor
from U504B so this will not hurt
anything.
Gary
W0DVN
PS: Not taking into account C516
and C517, I had previously stated
that voltage across the tuning
diodes depended one the voltage at
Q504 Drain. This was an error on my
part. Those two capacitors isolate
the DC on the tuning diodes from the
Drain of the oscillator FET.
Cn you short?
Gary
I just checked that voltage
again with the band switch
on 10 meters and the DC
voltage at that RFC505 is
20.52 DC. Hope that helps.
Jim VE1RB
On Sun,
Dec 29, 2024 at 8:37?PM
Gary Follett via ??<xntrick1948= [email protected]> wrote:
What is the voltage
on RFC 505?
Gary
W0DVN
Worked
on the VCO
board today
and founds
that the 5
volt regulator
is working
just fine 5.02
VDC. So am
thinking about
it trying to
decide what I
check next.
Might make a
chart of
voltages on
the
transistors
from the
working one
and compare to
the non
working
section.
73, Jim
Ve1RB
On Sat, Dec 28, 2024 at 11:08?PM Gary Follett via ??<xntrick1948= [email protected]>
wrote:
The power
supply that is
the subject of
this issue is
the 7805
regulator on
the VCO board.
That is the
one that
denies power
to just the
one VCO (high
bands, in this
case) when it
fails.
Regards,
Gary
W0DVN
On Dec
28, 2024, at
8:28?PM, Tony
N5DIM < tony@...> wrote:
The
WB4HFN website
has a section
with great
information
related to
that power
supply board.
I just used it
to resurrect a
TR7 that was
DOA. Good
luck. 73 Tony
N5DIM?
On
Dec 28, 2024,
at 5:52?PM,
Gary Follett
via??<xntrick1948=[email protected]>
wrote:
?Sounds
like you are
on the right
track. Don¡¯t
ocelot the
electrolytic
capacitors on
that supply as
well.
Gary
W0DVN
Gary,
I found a few
minutes to
work on the
TR7 and
discovered
that the high
VCO is not
working at
all. It does
have the 10
vdc supply
switch?on it
but I don't
know if that
reulagor?is
working or
not. I will
check it out
but have to
work on
getting the
metal shield
off. I Hope
that is the
problem but I
will work on
it maybe
tomorrow.
Thanks for all
your help.
73, Jim
VE1RB
On Fri, Dec 27, 2024 at 9:06?PM Gary Follett via ??<xntrick1948= [email protected]>
wrote:
It is
worth asking,
did the
failure of
your VCO board
(displaying
51.950) occur
on its own?
That is to
ask, did the
radio work
properly and
then just fail
or has it, as
long as you
have had it,
always
operated with
this fault??
If it
once worked
for you and
then failed,
then it would
make sense to
see what gets
disconnected
if those pins
are not in
line ?and look
for a way that
same thing
could happen
without the
pin alignment
problem.
The pin
alignment fix
is pretty easy
though, if the
board
alignment is
the cause. It
just SOUNDS
difficult.
That
whole DR7 was
always a
source of
issues due to
its complexity
and difficulty
of
installation.
I don¡¯t know
how a DR7
could even
endure the
stresses of
removal and
reinsertion
more than
once!
Gary?
W0DVN
Thanks
Tom. I printed
that off but
hope that is
not the
problem.
73, Jim
VE1RB
In 2010
there was a
thread
regarding the
Drake TR-7
display
showing
51950.0 on the
old retired
Drakelist.
The
thread is
archived at?
Please
click the link
so the owner
knows that we
find the
archive
useful.
Hope this
helps.
Tom, AG9X
================?
Below are
the posts from
Brian Koontz
WA3ITE, Jim
Shorney NU0C
and Garey
Barrell K4OAH
(SK)?
(just in
case Drake
TR-7 DR-7
problems
outlive the??site)
Re:
[Drakelist]
Almost there:
TR-7 display
issues --
FIXED!
Brian Koontz
Fri, 30 Jul
2010 20:36:54
-0700
Well, the TR-7
from hell is
now a fully
operational
TR-7 from
hell!
In preparation
for some
signal
tracing, I
decided to
extend the
DR-7
board using
the extenders
I have.? To do
this, you have
to unmount the
two voltage
regulators
mounted to the
chassis, and
jumper the
connector
farthest to
the right. ?(I
didn't bother
connecting the
up/down band
buttons.) ?Lo
and behold,
the display
worked!?
Some further
investigation
revealed that
the chassis
has warped
over
the years, so
the two
3-prong
connectors on
the VCO board
were no
longer in a
horizontal
line.? So I
was determined
to make sure
the
board was
fully seated
on all the
connectors.
To do this, I
had to drop
the front
panel.? Not a
major chore,
just
one knob to
remove (the
band knob) and
6 side screws.
With that now
out of the
way, it was an
easy job to
determine if
all the pins
were
where they
belonged.? The
only snag was
that the front
panel, when
canted
downwards,
angles the PTO
can upwards.?
So you have to
hold the
front panel
perpendicular
and steady
with slight
downward
pressure to
fully seat the
board.? Once
all the pins
were visually
confirmed to
be
seated, I
remounted the
front panel,
reattached the
regulators and
all
the
connectors,
and fired the
rig up.?
Everything now
seems to work!
It turns out
the original
DR-7 board was
indeed
defective as
well
(possibly
because it had
been seated
incorrectly).?
And a visual
confirmation
from topside
indicates the
chassis is,
indeed,
warped:
The screw hole
is misaligned
with the
mounting hole
in the board.?
So, for
archival
purposes in
case anyone
else decides
to search for
this problem:
?If the
display if
fixed on
"51950", one
possible cause
is that one or
more DR-7
pins, possibly
the VCO pins,
are not
correctly
seated.? The
best solution
is to drop the
front panel
and
confirm
visually that
the pins are
fully seated.
Now it's time
to get on the
air!
??--Brian/WA3ITE
=================?
Jim
Shorney Fri,
30 Jul 2010
23:17:58 -0700
On Fri, 30 Jul
2010 20:40:52
-0500, Brian
Koontz wrote:
>Well, the
TR-7 from hell
is now a fully
operational
TR-7 from
hell!
>
>Now it's
time to get on
the air!
Congratulations, Brian! You have been assimilated into the collective.
Resistance is
futile.
73
-Jim
=================
?
Garey
Barrell ?k4oah@...?via ?
Sat, Jul 31,
2010, 8:34?AM
to drakelist
Brian Koontz
wrote:
> Some
further
investigation
revealed that
the chassis
has warped
over
> the
years, so the
two 3-prong
connectors on
the VCO board
were no
> longer in
a horizontal
line.? So I
was determined
to make sure
the
> board was
fully seated
on all the
connectors.
>
>
>
> So, for
archival
purposes in
case anyone
else decides
to search for
> this
problem: ?If
the display is
fixed on
"51950", one
possible cause
> is that
one or more
DR-7 pins,
possibly the
VCO pins, are
not
> correctly
seated.? The
best solution
is to drop the
front panel
and
> confirm
visually that
the pins are
fully seated.
>
Brian -
Congratulations!! ? It's always nice when one 'comes together'.
Just as an
aside, someone
suggested
earlier (and
correctly)
that the
"51950"
problem may
indicate a
loss of the
500 kHz
reference
signal.?
You might find
it interesting
that the
left-most
three pin
connector on
the VCO board
is the 500 kHz
reference
signal!
Those pins on
the bottom of
the DR-7 are
ALWAYS a
problem, ya'
just
can't see
'em!!
Your 'trials'
have been an
interesting
'trip' for
others, thanks
for
documenting it
for us all.
73, Garey -
K4OAH
Glen Allen, VA
Drake 2-B,
4-B,
C-Line&
?TR-4/C
Service
Supplement CDs
<>
=================
?
Search
terms to make
this post
easier to
find:? Drake
TR-7 TR7 DR-7
DR7 display
frozen locked
stuck ?
51950??
51,950?? 51
950?? 5195?
51950.0 ?
51,950.0 ? 51
950 0
???
|
Right now, just a power supply. I am considering letting go of my A Line (late s/n, the transmitter is essentially an T-4XB) and my L7 (has a Harbach board, graphite tubes and I reworked the power supply chassis to use all PEM fasteners).
Steve Wedge, W1ES
Time flies like an arrow.? Fruit flies like a banana.
Sent with Proton Mail secure email.
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On Tuesday, December 31st, 2024 at 6:02 PM, Stan Gammons via groups.io <buttercup11421@...> wrote: Hi Steve,
On 12/31/24 16:57, Steve Wedge, W1ES/4 via groups.io wrote:
Let me know, as I am going to unleash a fairly good assortment of stuff onto the online auction site that shall remain unnamed...
Oh. What are you looking to part ways with?
73
Stan
KM4HQE
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Re: VE3EFJ third mixer mod for the R4C
2c. I would also be interested in the R4C printed circuit boards for the Sherman Mods...I've been collecting parts. TNX & 73, Tom Cunningham WA6VZN in Maryland -- Tom Cunningham WA6VZN
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Re: VE3EFJ third mixer mod for the R4C
After I found that Rob's Product Detector could help an R-4B, and heard that it was ok with him to make the kit ourselves, I re-designed
Rob's board except using SMD.? My board is therefore smaller that Rob's and used then currently available parts.? I batched up like a gillion
boards onto the cheap 4x4inch board specials in China.? For $6 I got a lifetime supply so I sent them out to anyone on this group that
wanted one or two.
?
I could give the complete Kicad project or just the needed gerbers to someone who would do another batch.? The Product Detector Kicad
project could be easily modified by adding the J-309 buffer to make the Mix-4 board too.
?
My R-4B install doc is in the Files area, somewhat easier install than Rob's since I cut one small trace and left all the Drake parts in place.
Easier if you ever want to go back to stock too.
73,
Gary
WB6OGD
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Hi Steve, On 12/31/24 16:57, Steve Wedge, W1ES/4 via groups.io wrote: Let me know, as I am going to unleash a fairly good assortment of stuff onto the online auction site that shall remain unnamed... Oh. What are you looking to part ways with? 73 Stan KM4HQE
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With me, it's the AC-4's I have run a switch to the MS-4 to channel to the speaker whichever rig I'm using at the moment. They take up space. The AC-4's sit on the floor and don't complain much ;-)
Speaking of which, I will have one AC-4 with the 120/240 switch option available. To folks on here, $175 + shipping and I will ship to Europe/Oz if you will put up with my b!tchings about the paperwork. I haven't touched this one other than run it as my backup bench supply, so it is working but not rebuilt.
Let me know, as I am going to unleash a fairly good assortment of stuff onto the online auction site that shall remain unnamed...
Steve Wedge, W1ES
Time flies like an arrow.? Fruit flies like a banana.
Sent with Proton Mail secure email.
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On Tuesday, December 31st, 2024 at 4:11 PM, Lyndon VE7TFX <lyndon@...> wrote: VE7PS via groups.io writes:
Besides...pretty sure there is one spare
MS-4 already lying under a desk somewhere.
That's the problem with MS-4s. They accrete in corners and under
tables, out of visible sight lines. It wasn't until a couple of
months ago I discovered I had four of the bloody things! None of
which I have space for on the radio desk. I'm keeping the nicest
one, and have sold two of the others. One to go ...
--lyndon
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Hi Stan,
All that was ever installed for an R-4B here in the lab were a few PD-4 product detectors. The AMP-4 needs a good 12 to 14 volt supply at several hundred mA that doesn't exist in an R-4B. While the AGC attack distortion was much less with the PD-4, the audio distortion was still there with the audio output tube. The tube amp wasn't as distortion free as I expected.
Let¡¯s see if the updated Gerber files make it to Colorado and go from there. There are some parts for all the kits that have become harder to source from new old stock. I would of course be more than happy to see someone run a new batch of boards.
Attached is a PDF for installing a PD-4 in an R-4B. As to coming up with 12 volts, could a voltage doubler be used off the filament line? It might be worth considering use of a less power hungry LM-380 instead of my LM-383 circuit for the R-4C. 100 mW of power is pretty loud into an MS-4 or MS-7 speaker.
Rob, NC0B
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-----Original Message-----
From: Stan Gammons [mailto:buttercup11421@...]
Sent: Tuesday, December 31, 2024 3:16 PM
To: Rob Sherwood.
Subject: Drake mods
Hi Rob,
I saw the thread on the Drake-radio group about mods you had for the R4C
and gerber files for the boards. What mods did you offer for the Drake
R4B?? Hopefully one to get rid of the really hot running audio tube.? If
so, would you be willing to share that mod and possibly the gerber files
to make the board?
Happy New Year!
73
Stan
KM4HQE
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Rob Sherwood
Jim Shorney
Paul Christensen
Gary WB6OGD