Re: 6JB6 Tube Tester Adapter
I still have 17 PCBs in stock for this project. Price is $7.00 including postage to North American addresses.
Please contact me off list if you are interested.
--
73, Bernie. VE3FWF
Real?radios glow in the dark
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Re: MN-2000 Technical implementation
Jim,
Upon closer inspection while not trying to read the schematic while is rotated 90 degrees, I realized that the MN-2000 circuit is not a T configuration.
I do have a couple of questions for you:
-I don¡¯t see why you feel that the MN-2000 circuit is an SPC circuit. It appears to me to be a PI configuration. Both designs do have a tapped capacitor impedance transformer on the output, but the SPC design looks like a T network to me.
-In the video, I am curious why when the frequency is changed with both tuners the Z stays 50 ohms while the SWR goes up. In the SPC tuner case the SWR went up to 1.7 while the Z stayed at 50 ohms. Is Z not the impedance?
-- Bill N0CU
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Re: MN-2000 Technical implementation
Thanks, thought this was a nice video on the difference between SPC and T circuits:
PS: This is a great group. I appreciate all the help as I try to better educate myself on my Drake gear. 73s
That's because the MN-2000 is an SPC type of tuner. See below. But
the MN-2000 uses fixed caps for C1 in this diagram below, as well as
C2 shown below, is a split stator type of cap.
The MN-2000, uses two independent caps for C2.
In reality, the MN-2000 is more like the second diagram below. As
said before, C1 is the fixed caps that are changed with the band
switch coil.
Jim W7RY
On 4/2/2023 10:32 AM, Jim VE7RF wrote:
Both the references sited, are not even close to? the MN-2000.
IF u look at the schematic for the MN-2000, it consist of a PI
network, followed by a series variable cap in the output leg to
the ant.?
The 1st....' C1 cap' consists of a mess of paralleled? fixed?
mica caps, that are progressively switched in by the progressive
bandswitch.? ?On 10m, they use 5 x? 68 pf caps in parallel.
Reason is, the mica caps don't handle RF current at the upper HF
freqs, so 5 are used in parallel.? However, the mica's are
stable, and don't drift.? On each lower band, a bigger and
bigger mica is added to the grand total..that makes up the 'C1'
cap.? ?The coil assy is identical to what's used in the L4B
linear amp.? The bandswitch in the MN-2000 is also identical to
the bandswitch in the L4B linear.?
The C2 cap in the MN-2000 is a 20-245 pf? air variable. The C3
cap is also a 20-245 pf air variable, but is wired in series
with the output..then off to the ant.??
?
Here's?a link to the manual...which includes the schematic at
the end.?
--
Thanks and 73, Jim W7RY
|
Re: MN-2000 Technical implementation
I agree with Bob that the T network can be thought of as two series connected L-networks. Although the L network can do the required impedance transformation in most applications, its main limitation is that, unlike the three component matching networks, it cannot vary the circuit Q. With the L network, the Q is a function of the input and output impedance, so you are stuck with a fixed Q, which in most cases is very low. Although this keeps the losses low, it may be too low to reduce harmonics sufficiently. The Pi and T networks can vary Q in addition to doing the needed impedance transformation, however, the higher Q results in higher loss. I believe that the main reason the T network is rarely used in Ham applications is that it is a high pass function, which does not provide any rejection of harmonics.
?
-- Bill N0CU
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Re: MN-2000 Technical implementation
Nope. Its an SPC tuner circuit.
Search for it.
Jim W7RY
On 4/2/2023 10:46 AM, Bill Leonard N0CU
wrote:
This
looks like a T network. This configuration?is not as common as
the Pi and L. The attached artical is just one of many on the
web that discuss how these networks work. It may not be the
best article, it was just one I thought looked like it would
address your questions.
On Sun, Apr 2, 2023 at 9:32?AM
Jim VE7RF < jim.thom@...>
wrote:
Both the references sited, are not even close to? the
MN-2000.
IF u look at the schematic for the MN-2000, it consist of a
PI network, followed by a series variable cap in the output
leg to the ant.?
The 1st....' C1 cap' consists of a mess of paralleled?
fixed? mica caps, that are progressively switched in by the
progressive bandswitch.? ?On 10m, they use 5 x? 68 pf caps
in parallel. Reason is, the mica caps don't handle RF
current at the upper HF freqs, so 5 are used in parallel.?
However, the mica's are stable, and don't drift.? On each
lower band, a bigger and bigger mica is added to the grand
total..that makes up the 'C1' cap.? ?The coil assy is
identical to what's used in the L4B linear amp.? The
bandswitch in the MN-2000 is also identical to the
bandswitch in the L4B linear.?
The C2 cap in the MN-2000 is a 20-245 pf? air variable. The
C3 cap is also a 20-245 pf air variable, but is wired in
series with the output..then off to the ant.??
?
Here's?a link to the manual...which includes the schematic
at the end.?
--
Thanks and 73, Jim W7RY
|
Re: MN-2000 Technical implementation
That's because the MN-2000 is an SPC type of tuner. See below. But
the MN-2000 uses fixed caps for C1 in this diagram below, as well as
C2 shown below, is a split stator type of cap.
The MN-2000, uses two independent caps for C2.
In reality, the MN-2000 is more like the second diagram below. As
said before, C1 is the fixed caps that are changed with the band
switch coil.
Jim W7RY
On 4/2/2023 10:32 AM, Jim VE7RF wrote:
Both the references sited, are not even close to? the MN-2000.
IF u look at the schematic for the MN-2000, it consist of a PI
network, followed by a series variable cap in the output leg to
the ant.?
The 1st....' C1 cap' consists of a mess of paralleled? fixed?
mica caps, that are progressively switched in by the progressive
bandswitch.? ?On 10m, they use 5 x? 68 pf caps in parallel.
Reason is, the mica caps don't handle RF current at the upper HF
freqs, so 5 are used in parallel.? However, the mica's are
stable, and don't drift.? On each lower band, a bigger and
bigger mica is added to the grand total..that makes up the 'C1'
cap.? ?The coil assy is identical to what's used in the L4B
linear amp.? The bandswitch in the MN-2000 is also identical to
the bandswitch in the L4B linear.?
The C2 cap in the MN-2000 is a 20-245 pf? air variable. The C3
cap is also a 20-245 pf air variable, but is wired in series
with the output..then off to the ant.??
?
Here's?a link to the manual...which includes the schematic at
the end.?
--
Thanks and 73, Jim W7RY
|
Re: MN-2000 Technical implementation
I agree with Jim, VE7RF, except the configuration could be thought of as two series connected L-networks. Starting at the source end (TX, RX, TVCR) the first L-network is a shunt capacitance then a series inductance. The following L-network is a shunt capacitance then a series capacitance to the load (antenna). I guess the network could also be thought of as a different theme on the Pi-L network.
The present issue of QEX has an article on L-notworks. It is not for the faint of heart as it contains a lot of "j-omega", i.e., mathematics. If nothing else, one can view the various types of L-networks, one being the capacitance/capacitance type described above.
73,
On Sunday, April 2, 2023 at 01:10:33 PM EDT, Sean (KK6BEB) <seanlynch@...> wrote:
Thanks Bill and thanks Jim for the reference to the schematic. I¡¯m learning a lot. KK6BEB?
This looks like a T network. This configuration?is not as common as the Pi and L. The attached artical is just one of many on the web that discuss how these networks work. It may not be the best article, it was just one I thought looked like it would address your questions.
On Sun, Apr 2, 2023 at 9:32?AM Jim VE7RF < jim.thom@...> wrote: Both the references sited, are not even close to? the MN-2000.
IF u look at the schematic for the MN-2000, it consist of a PI network, followed by a series variable cap in the output leg to the ant.?
The 1st....' C1 cap' consists of a mess of paralleled? fixed? mica caps, that are progressively switched in by the progressive bandswitch.? ?On 10m, they use 5 x? 68 pf caps in parallel. Reason is, the mica caps don't handle RF current at the upper HF freqs, so 5 are used in parallel.? However, the mica's are stable, and don't drift.? On each lower band, a bigger and bigger mica is added to the grand total..that makes up the 'C1' cap.? ?The coil assy is identical to what's used in the L4B linear amp.? The bandswitch in the MN-2000 is also identical to the bandswitch in the L4B linear.?
The C2 cap in the MN-2000 is a 20-245 pf? air variable. The C3 cap is also a 20-245 pf air variable, but is wired in series with the output..then off to the ant.??
?
Here's?a link to the manual...which includes the schematic at the end.?
|
Re: MN-2000 Technical implementation
Thanks Bill and thanks Jim for the reference to the schematic. I¡¯m learning a lot. KK6BEB?
This looks like a T network. This configuration?is not as common as the Pi and L. The attached artical is just one of many on the web that discuss how these networks work. It may not be the best article, it was just one I thought looked like it would address your questions.
On Sun, Apr 2, 2023 at 9:32?AM Jim VE7RF < jim.thom@...> wrote: Both the references sited, are not even close to? the MN-2000.
IF u look at the schematic for the MN-2000, it consist of a PI network, followed by a series variable cap in the output leg to the ant.?
The 1st....' C1 cap' consists of a mess of paralleled? fixed? mica caps, that are progressively switched in by the progressive bandswitch.? ?On 10m, they use 5 x? 68 pf caps in parallel. Reason is, the mica caps don't handle RF current at the upper HF freqs, so 5 are used in parallel.? However, the mica's are stable, and don't drift.? On each lower band, a bigger and bigger mica is added to the grand total..that makes up the 'C1' cap.? ?The coil assy is identical to what's used in the L4B linear amp.? The bandswitch in the MN-2000 is also identical to the bandswitch in the L4B linear.?
The C2 cap in the MN-2000 is a 20-245 pf? air variable. The C3 cap is also a 20-245 pf air variable, but is wired in series with the output..then off to the ant.??
?
Here's?a link to the manual...which includes the schematic at the end.?
|
Re: MN-2000 Technical implementation
This looks like a T network. This configuration?is not as common as the Pi and L. The attached artical is just one of many on the web that discuss how these networks work. It may not be the best article, it was just one I thought looked like it would address your questions.
On Sun, Apr 2, 2023 at 9:32?AM Jim VE7RF < jim.thom@...> wrote: Both the references sited, are not even close to? the MN-2000.
IF u look at the schematic for the MN-2000, it consist of a PI network, followed by a series variable cap in the output leg to the ant.?
The 1st....' C1 cap' consists of a mess of paralleled? fixed? mica caps, that are progressively switched in by the progressive bandswitch.? ?On 10m, they use 5 x? 68 pf caps in parallel. Reason is, the mica caps don't handle RF current at the upper HF freqs, so 5 are used in parallel.? However, the mica's are stable, and don't drift.? On each lower band, a bigger and bigger mica is added to the grand total..that makes up the 'C1' cap.? ?The coil assy is identical to what's used in the L4B linear amp.? The bandswitch in the MN-2000 is also identical to the bandswitch in the L4B linear.?
The C2 cap in the MN-2000 is a 20-245 pf? air variable. The C3 cap is also a 20-245 pf air variable, but is wired in series with the output..then off to the ant.??
?
Here's?a link to the manual...which includes the schematic at the end.?
|
Re: MN-2000 Technical implementation
Both the references sited, are not even close to? the MN-2000.
IF u look at the schematic for the MN-2000, it consist of a PI network, followed by a series variable cap in the output leg to the ant.?
The 1st....' C1 cap' consists of a mess of paralleled? fixed? mica caps, that are progressively switched in by the progressive bandswitch.? ?On 10m, they use 5 x? 68 pf caps in parallel. Reason is, the mica caps don't handle RF current at the upper HF freqs, so 5 are used in parallel.? However, the mica's are stable, and don't drift.? On each lower band, a bigger and bigger mica is added to the grand total..that makes up the 'C1' cap.? ?The coil assy is identical to what's used in the L4B linear amp.? The bandswitch in the MN-2000 is also identical to the bandswitch in the L4B linear.?
The C2 cap in the MN-2000 is a 20-245 pf? air variable. The C3 cap is also a 20-245 pf air variable, but is wired in series with the output..then off to the ant.??
?
Here's?a link to the manual...which includes the schematic at the end.?
http://www.radiomanual.info/schemi/ACC_matching/Drake_MN-2000_user.pdf
|
Re: For Sale Beautiful 4A Line Sacramento, CA
Hi Gary,
The T-4X was on the center hump in transceive mode. The R-4 was on the passenger side mounted under the glove compartment. ?The DC-4 had an output to run the receiver by simply plugging it in. I don¡¯t remember whether I installed resistive spark plugs,
a term I had forgotten.
At that point right out of college I had no separate mobile rig. Later I had a permanent TR-4 and then a TR-4C. ?The TR-4 at some point had the hard wired noise blanker upgrade, and the TR-4C had the plugin 34PNB.?
The blankers handled the ignition noise pretty well, plus ground bonding the hood and tailpipe may have helped. ?It is possible by the time the TR-4C came along I may have had a Ford Fairmont. ?
For some reason today I run an IC-706MkIIG in my 2007 RAV4. ?Where could we mount a TR-4 in any modern car? ?Hi Hi. Too bad I don¡¯t have any photos from those days.?
In the last 30 years I had a 4Runner that was awful with ignition and fuel pump noise, then a quiet Camry, and now a quiet RAV4 with few RFI creating electronic gizmos. I once took a mobile trip to CA in a 2006 Prius. ?One terrible RFI generator. ?Not
even quiet on 2 meter FM simplex! ?It was an interesting experiment is all I can say.?
toggle quoted message
Show quoted text
On Apr 1, 2023, at 4:51 PM, wb6ogd <garywinblad@...> wrote:
?
Wait a minute.. Rob, you got a Drake 4 line in a 67 Cougar??? WOW..? Did you stack it in the passenger seat or what?
Back then ignition noise was the problem.? I remember buying new resistor type wires for my TIger Ford V8.. then it was usable.
73,
Gary
WB6OGD
?
|
No, I have not done the mod. I would point out though that while looking at the internals the plates may look similar, the 6146 has about twice the plate dissipation of the 6JB6.? The 6146 is about 35 watts and the 6JB6 is 17.5. It is a shame that Drake did not use the 6146 as it could have easily been incorporated at the time. They probably had similar costs. I can remember 6146's selling for $3.50. The mod is not a big deal for someone that has the time and experience. As he pointed out in his article, a lot of the myths like having to recess the tube and that the plate voltage is not high enough are basically bogus. I never liked sweep tubes much but the old 6DQ5 used in early color sets made a good novice transmitter. It has a 24 watt dissipation rating. 6146's in a Drake using the Drake supply would have as much output as the 6JB6's and they would be loafing doing it.? The 6883A is the 12V version and can be found for a cheaper price. For the T4 where the 6JB6's are wired in series, these could be used wired in parallel.
--
Doug, WA3DSP
|
The two tubes are quite different. The 6146x was designed as an RF power amplifier tube for high duty cycle transmitter service up to 60 MHz, with operational specs described up to 175 Mhz, in various classes of operation (including linear) and signal modes. The xJB6 tubes were pulse rated tubes designed to be used in low frequency (for us) horizontal deflection circuits. That's all. Sylvania was the only company that bothered to publish specs for RF for their tubes. The 6146 will take more punishment in ham use than most any sweep tube. The only sweep that has ever impressed me was the late-in-the-game 6MJ6. I once had a pair glowing red when a 10 Meter amp faulted on me and I didn't notice right away. After I let them cool down they were just fine. If you want to compare pulse ratings, the 6293 variant you mentioned was rated for 3000V plate voltage with 1.5A peak plate current for "Typical operation with rectangular wave shapes" in the recommended test circuit. The JB6 asks for 770V plate with 550 mA peak cathode current. 73 -Jim NU0C On Sat, 01 Apr 2023 11:32:13 -0700 "Rick WA6III" <myr748@...> wrote: 6146's are no more rugged than 6JB6's since they have similar plate dissipation.? Remember, sweep tubes in general are rated to operate 24-7 in horizontal sweep osc service with high peak currents and voltages.
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Re: For Sale Beautiful 4A Line Sacramento, CA
Wait a minute.. Rob, you got a Drake 4 line in a 67 Cougar??? WOW..? Did you stack it in the passenger seat or what?
Back then ignition noise was the problem.? I remember buying new resistor type wires for my TIger Ford V8.. then it was usable.
73,
Gary
WB6OGD
?
|
Re: 2C S Meter Pegs In Standby
Mine goes all the way to 60, thought it doesn't "peg".?
--
72/73 de Steve K9NUD ..
|
Re: MN-2000 Technical implementation
For the group, I *think I understand now. The MN-2000 band switch varies course-grained *inductive reactance by shorting the inductor. The two capacitors give you :
1. Capacitive reactance? 2. Capacitive resistance?
This is my best guess as far as how the MN-2000 works.
If there are any Elmers out there with a better understanding, I¡¯m all ears.
Sean KK6BEB?
On Sat, Apr 1, 2023 at 10:11 AM Sean Lynch < seanlynch@...> wrote: Thanks Frank. So it seems like (specific to the MN-2000) the band selection knob is tapping the inductor coil and then we have two (inline?) air capacitors adjusting reactance. I¡¯ve seen simple hombrew L networks with a single inductor and a single capacitor. I¡¯m trying to understand why the MN-2000 needs *two capacitors. Still learning¡.
KK6BEB? On Sat, Apr 1, 2023 at 10:03 AM Frank Barnes < fbw4npn@...> wrote: There is some good information and references about tuners and more, here:
On Sat, Apr 1, 2023 at 12:38?PM Sean (KK6BEB) < seanlynch@...> wrote: Thanks Ralph, the document you sent does look similar. I appreciate that and will study it.
I do have the instructions for the MN-2000 and have used it many times. I feel like a capable ¡°operator¡± of the tuner but would like to take that to a deeper level of understanding.?
Sean KK6BEB?
You may want to look at thie?
Seems to be the same design without the balun coil.
It is not the conventional L or PI? type of network.
Much harder to tune than the typical PI network, especially if used to the PI.? I hope you have the instructions on how to tune it, if not it will be very difficult to tune.
One does not adjust the inductance.? One is for the resistant part and the other for reactance ( indictive or capacitive)
Ralph ku4pt
On Saturday, April 1, 2023 at 11:41:29 AM EDT, Sean (KK6BEB) < seanlynch@...> wrote:
Hello, I decided recently that I really want to understand antenna tuners better. I opened my MN-2000 and was so impressed my the build quality. I see the two large air variable capacitors and I wanted to better understand how one side is adjusting inductance and the other capacitance.?
Is the MN-2000 based on one of the usual ¡°L Network ¡° designs?
I just really want to understand this thing at a ?deeper level and would love to be directed to some documentation.
Thanks KK6BEB? Sean -._,_._,_
--
Frank Barnes
W4NPN
Chapel Hill, NC
Grid Square FM05
Cell 919.260.7955
|
On Mon, Mar 27, 2023 at 05:40 PM, wb6ogd wrote:
Whoops, my message was lost¡
NO, I haven¡¯t done the 6146 mod and don¡¯t?
plan to unless I blew my 6JB6s and I
couldn¡¯t find any more. ?Seeing as how I
have NEVER LOST ANY final since 1965, I
am doubtful I ever will have to!
73,
Gary?
WB6OGD?
I would "second" Gary's opinion..... I bought my C-Line in 1975 and only replaced the 2 6JB6's about a year or so ago......and it's only because I killed them. With that kind of performance from 6JB6's, I'll have enough for a lifetime! 6146's are no more rugged than 6JB6's since they have similar plate dissipation.? Remember, sweep tubes in general are rated to operate 24-7 in horizontal sweep osc service with high peak currents and voltages. The only 6146 "style" tube that comes close is the 6293! Cheers, Rick --
73/Rick
WA6III
*Every post is created using Linux
|
Re: MN-2000 Technical implementation
There is some good information and references about tuners and more, here:
On Sat, Apr 1, 2023 at 12:38?PM Sean (KK6BEB) < seanlynch@...> wrote: Thanks Ralph, the document you sent does look similar. I appreciate that and will study it.
I do have the instructions for the MN-2000 and have used it many times. I feel like a capable ¡°operator¡± of the tuner but would like to take that to a deeper level of understanding.?
Sean KK6BEB?
You may want to look at thie?
Seems to be the same design without the balun coil.
It is not the conventional L or PI? type of network.
Much harder to tune than the typical PI network, especially if used to the PI.? I hope you have the instructions on how to tune it, if not it will be very difficult to tune.
One does not adjust the inductance.? One is for the resistant part and the other for reactance ( indictive or capacitive)
Ralph ku4pt
On Saturday, April 1, 2023 at 11:41:29 AM EDT, Sean (KK6BEB) < seanlynch@...> wrote:
Hello, I decided recently that I really want to understand antenna tuners better. I opened my MN-2000 and was so impressed my the build quality. I see the two large air variable capacitors and I wanted to better understand how one side is adjusting inductance and the other capacitance.?
Is the MN-2000 based on one of the usual ¡°L Network ¡° designs?
I just really want to understand this thing at a ?deeper level and would love to be directed to some documentation.
Thanks KK6BEB? Sean -._,_._,_
-- Frank Barnes
W4NPN
Chapel Hill, NC
Grid Square FM05
Cell 919.260.7955
|
Re: MN-2000 Technical implementation
Thanks Ralph, the document you sent does look similar. I appreciate that and will study it.
I do have the instructions for the MN-2000 and have used it many times. I feel like a capable ¡°operator¡± of the tuner but would like to take that to a deeper level of understanding.?
Sean KK6BEB?
You may want to look at thie?
Seems to be the same design without the balun coil.
It is not the conventional L or PI? type of network.
Much harder to tune than the typical PI network, especially if used to the PI.? I hope you have the instructions on how to tune it, if not it will be very difficult to tune.
One does not adjust the inductance.? One is for the resistant part and the other for reactance ( indictive or capacitive)
Ralph ku4pt
On Saturday, April 1, 2023 at 11:41:29 AM EDT, Sean (KK6BEB) < seanlynch@...> wrote:
Hello, I decided recently that I really want to understand antenna tuners better. I opened my MN-2000 and was so impressed my the build quality. I see the two large air variable capacitors and I wanted to better understand how one side is adjusting inductance and the other capacitance.?
Is the MN-2000 based on one of the usual ¡°L Network ¡° designs?
I just really want to understand this thing at a ?deeper level and would love to be directed to some documentation.
Thanks KK6BEB? Sean -._,_._,_
|
Re: Drake R4 - Trying to improve the receiver sensitivity, and S meter sensitivity
Thanks guys,
I was able to achieve -1.35vdc off TO2 from adjusting R87
zero adjusted meter to S1
R40 adjustment while calibrator running ran out of range with a max meter deflection of only 2db over 9
here is a QSO received on both the FT-901DB and the Drake R4 as a comparison.?
901 noise floor is S-7, R4 noise floor is S-1
i think I can hear some of the noise floor in the weaker stations on the 901DM.?
the Drake R4 signals do not give mush meter deflection but sound good on the Drake.?
?
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Ham Radio
Rob Sherwood
Doug Crompton WA3DSP
Jim Shorney
Gary WB6OGD
Steve K9NUD