Re: DR7 fitting partial success.
Hi Roger
Just seen your reply.
Looks like the problem now is with segment a the top one.
All the others are working.
Will check that centre wire tomorrow.
Kind Regards
Mike
G3ZCC
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Re: DR7 fitting partial success.
Hi everyone
Well after a day checking those three pins, fitting? 5mm blue LED's to the PTO and meter, fitting it all back together still a problem.
looks like segment a if I read the schematic correctly.?
Back to the drawing board.
Kind Regards
Mike
G3ZCC
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Hi all. Thanks for the fine info and offers.? The original plan was to use an old Heathkit unit I had? but? I've managed to obtain a 2-BQ with one fitted.
So the connector is no longer required.
Regards
Gary ZL2AKI
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Re: L75 Amp Main Power Switch Availability
On Sun, Mar 14, 2021 at 08:21 PM, Jim Shorney wrote:
<Hmm... They survived through three engineering generations and served the purpose over the decades of real world use. Real HV fuses are expensive for a new build. Even the great W8JI <espouses the use of fault limiting resistors, although he prefers higher values.
<73
<-Jim
<NU0C
##? ?You won't see any amps other than drake, using a .82 ohm? @? 2 watt? resistor.....for a... 'hv? fuse'.? ?New, correctly sized? HV? fuses are cheap, and meet? ?UL /? CSA? standards.? ?Drake could have bought thousands of em? at whole sale prices.? ?W8JI? typ will use 10 ohm,? or? 20? ohm max, for the? current limiting resistor (aka...'glitch resistor').? ?ARRL handbook? sez to use? 10-15 ohms? per KV.? ?After building? 38? x hb? B+? supplies over the years, and experimenting with different value glitch resistors,? I settled on? 50 ohms, regardless of the? actual? B+? value.? ?But it's a two edged sword.? ?Higher values will limit fault current to a lower value.... BUT dissipate more heat, depending on? mode, and how much average plate current involved.? ?Higher value? glitch resistors? also have a higher? V drop? across them...? ( which will increase even more, with higher plate currents).?
##? In? L4B? size amps,? ?with say? 2650 vdc no load..and a fault occurred,? it's then just 2650 /? 50 ohms =? ? 53 amps of fault current.? And? ?53 amps of fault current will open off that? BUSS? 750 ma HV fuse in? < 2 msecs? every time.? ?On a L4B, with? 800 ma peaks on? ssb,? the? V drop on peaks is .8? X? 50 ohms? = 40 vdc? V drop on the loaded? B+.? ? Average plate current on ssb mode is? typ? 400 ma( with processing).? ?(.4 X.4 )? ?X 50 ohms =? ? 8 watts dissipation? in the? 50 ohm glitch R.? ?( and? 32 watts if a? 800 ma? dead cxr, like tuning up with a cxr).? ?Hence my use of a? simple? 50 ohm, 50 watt wire wound? for the glitch? R.?
##? On the bigger? HB? B+? supplies, with a lot more filter C,? ?I use globar type AS? resistors.? The? AS types are designed for glitch service, and will handle a lot of joules of? energy...and also a lot of HV.? Typ,? 4 x 200 ohm, type? AS? resistors are wired in parallel..and also fan cooled.? ?But that's what's required for 5-8 kv dc? supplies..and tubes that? suck 1.5? to 3 amps of plate current.? ?3 amps? ccs? into 50 ohms? =? ?450 watts, which is a bunch.? The type? AS? resistors are? 18"? long x 1.5"? diam,? rated for? 225 watts each /? 900 w? total.? They run hot when used in ccs modes.? ?Lower? duty cycle modes like? ssb is a non issue,? only? ?1/4 the? dissipation...same as? the 50 ohms used in the? L4B? B+? supply.
Jim? VE7RF
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Re: 2B Second Mixer Bias Issue
John,
Thank you for the follow-up report.
73,
Michael Smith, N4KZO
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Re: DR7 fitting partial success.
Sounds like a good idea. Please post a pic sometime if you get a chance. 73 -Jim NU0C On Mon, 22 Mar 2021 11:16:30 -0500 "Gary Follett" <xntrick1948@...> wrote: That¡¯s the term I was looking for, fish paper.
Drake may not have widely implemented that ECO but I have had several TR7¡¯s that did have it and I installed it on every one that came through here. It is a tight fit and the results of that short are not leading to a happy ending. If the short is short-lived, you only lose the segments but a longer-term short will destroy the display. No down side to doing this, big downside to not doing it.
Gary. W0DVN
On Mar 21, 2021, at 11:15 AM, Jim Shorney <jshorney@...> wrote:
?
Interesting. I don't recall having seen this. Fish paper maybe?
73
-Jim
NU0C
On Sun, 21 Mar 2021 11:00:19 -0500
"Gary Follett" <xntrick1948@...> wrote:
Drake, in later radios, glued a grey piece of high voltage cardboard on top the PTO assembly. Your radio looks like a pretty early one so may not have this.
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Re: DR7 fitting partial success.
That¡¯s the term I was looking for, fish paper.
Drake may not have widely implemented that ECO but I have had several TR7¡¯s that did have it and I installed it on every one that came through here. It is a tight fit and the results of that short are not leading to a happy ending. If the short is short-lived, you only lose the segments but a longer-term short will destroy the display. No down side to doing this, big downside to not doing it.
Gary. W0DVN
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On Mar 21, 2021, at 11:15 AM, Jim Shorney <jshorney@...> wrote:
?
Interesting. I don't recall having seen this. Fish paper maybe?
73
-Jim
NU0C
On Sun, 21 Mar 2021 11:00:19 -0500
"Gary Follett" <xntrick1948@...> wrote:
Drake, in later radios, glued a grey piece of high voltage cardboard on top the PTO assembly. Your radio looks like a pretty early one so may not have this.
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Re: 2B Second Mixer Bias Issue
Well, the mystery is solved. ?Once I pumped a modulated signal in at the ant term and heard the tone in the speaker, I knew this stage was working.
I suspected the meter was loading the osc when measuring that pin. ?Turns out that is the problem.
A couple days ago I stumbled across a two year old post on another forum where the fellow had the same problem on his 2b. ?He measured +3V on pin one instead a negative. ?He rightly suspect loading and wrapped a 100K resistor around the tip of the meter¡¯s probe and touch the other resistor lead to pin one and got the correct negative voltage.
Thanks to everyone for their help. ?I learned where a lot of the parts are located.
For you 2B owners, it¡¯s worth making a note about this on the voltage chart in the manual.
de K8NN
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Re: DR7 fitting partial success.
Hi Mike, The loose left wire is for segment F. The center wire is for segment A. The right wire is for segment B. Suggest re-soldering all three wires.
You can use an ohmmeter to check for continuity from the F, A & B wires to the the F, A & B segments for the 4 LSD (right) digits at the LEDs mounting angle header. From the front of the DR7 pin 1 is the far left angle header pin. From the F wire there should be continuity to pin 22. From the A wire there should be continuity to pin 21. From the B wire there should be continuity to pin 20.
I don't know why DF4NW decided to use the 3 wires as the F, A & B signals are already on the aftermarket LED circuit board. Likely to make the new circuit board look more like the originals LEDs installation.
73
Roger VE7LB
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I¡¯m currently using a Nye Viking MB-V-A. Built like a tank and available for around $300. I¡¯ve been using it to drive balanced antennas with the L7 and it takes everything I can give it.?
Steve Wedge, W1ES/4
Time flies like an arrow.? Fruit flies like a banana.
Sent from ProtonMail Mobile
On Sun, Mar 21, 2021 at 14:22, AC9PA via groups.io < byroncordes@...> wrote: Well if where talking tuners ! Ten Tec L tuner works but cost is high .
On Mar 21, 2021, at 12:48 PM, Jim Shorney <jshorney@...> wrote:
?
I was just thinking the same thing. I have a Murch sitting atop my MN2700. And a second homebrew knockoff awaiting cleanup. Spent less money than a night on the town for both combined.
73
-Jim
NU0C
On Sun, 21 Mar 2021 16:45:41 +0000
"Dick" <w1ksz@...> wrote:
> Look for a Mutch UT-2000B (not the A). They go for short money
> and will load up the proverbial bedspring.
>
> 73, Dick, W1KSZ
> ________________________________
> From: [email protected] <[email protected]> on behalf of Billy Pickering KO4INE <pickeringw@...>
> Sent: Sunday, March 21, 2021 9:16 AM
> To: [email protected] <[email protected]>
> Subject: Re: [DRAKE-RADIO] MN2000
>
> We have a huge hamfest coming up this next Saturday in Sevierville that I'm going to keep an eye out there and see what I can find. Thanks everyone.
>
>
>
>
>
>
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I had one of these years ago. I remember on 160 that it wouldn¡¯t do legal limit ¡ª about 800W before it arced. Good tuner, though.?
Steve Wedge, W1ES/4
Time flies like an arrow.? Fruit flies like a banana.
Sent from ProtonMail Mobile
On Sun, Mar 21, 2021 at 12:45, Dick < w1ksz@...> wrote:
Look for a Mutch UT-2000B (not the A). They go for short money
and will load up the proverbial bedspring.
73, Dick, W1KSZ
We have a huge hamfest coming up this next Saturday in Sevierville that I'm going to keep an eye out there and see what I can find. Thanks everyone.
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Re: DR7 fitting partial success.
Hi Fred?
I was going to buy a TR7 back in the day, got warned off, spent more money and bought a Triumph Stag.
After three engines I sold it and bought a Lotus Sunbeam.
Best car I ever had,
Kind Regards
Mike
G3ZCC
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Re: DR7 fitting partial success.
Hi Roger
Thanks for that, I just checked and looking at the board from the front, there is a bad solder joint on the left wire link of the three.
Just resoldered it, it came off in my hand.
Fitting some blue LED's to the meter and PTO today replacing the two bulbs, cant wait to check the DR7 out after everything is all back together.
Kind Regards
Mike
G3ZCC??
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Re: DR7 fitting partial success.
Hahaha
I bought a blue Triumph TR7 like that but a hard top in 1985 with my ill gotten gains from my first job overseas
AND
I bought? a Drake B line. The previous owner had upgraded to a Drake TR7
73 Fred G4BWP
Hoarder of fine valved radios
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Re: WTB: lonely Final Cage for T-4Xb
Hi Ryan
No luck so far with a replacement.?
Bernie suggested that I Fab one from His me Depot material. That¡¯s a possibility.?
If you have time, please take a look.? I would gladly reimburse for the cage plus postage.?
Thank you! ?73 Bob KQ2Q. Danielsville. GA. 30633
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Show quoted text
On Mar 21, 2021, at 10:23 PM, Ryan Scott via groups.io <tweeker42000@...> wrote:
?
Any Luck?? I have some parts units in the garage.? I can look tomorrow after work
Ryan N7QJ
On Saturday, March 20, 2021, 11:50:22 AM PDT, kq2q <kq2q@...> wrote:
Hello All
Looking for a final cage for my T-4Xb
I have reworked the Chassis and need the Final Cage
Thanks
?Bob. kQ2Q. Danielsville GA
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I posted a link the Lew McCoy's article in an earlier message. And here are some shots of the homebrew unit I have, likely build from guidance found in that article. 73 -Jim NU0C On Mon, 22 Mar 2021 01:01:24 +0000 (UTC) "Ralph Mowery via groups.io" <ku4pt@...> wrote: Murch did not try to claim it was his design but was a copy of the Ultimate Transmatch? by Lewis McCoy.
Murch just put it into production and there were several versions of it over the years.
While I am not sure, I think Murch made many of the components as they were hard to find.
Ralph ku4pt
On Sunday, March 21, 2021, 04:03:48 PM EDT, Steve Bookout, NR4M <steve@...> wrote:
None of us know everything.?¡®Murch¡¯ is an old school brand of basic, well built, tuners.?
Much better, and beefier than many current tuners.?
73 de Steve, NR4M?
On Mar 21, 2021, at 3:57 PM, Billy Pickering KO4INE <pickeringw@...> wrote:
?It's another brand of antenna tuner made by Murch Electronics.
_._
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Re: WTB: lonely Final Cage for T-4Xb
Any Luck?? I have some parts units in the garage.? I can look tomorrow after work
Ryan N7QJ
On Saturday, March 20, 2021, 11:50:22 AM PDT, kq2q <kq2q@...> wrote:
Hello All
Looking for a final cage for my T-4Xb
I have reworked the Chassis and need the Final Cage
Thanks
?Bob. kQ2Q. Danielsville GA
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Re: DR7 fitting partial success.
Hi Mike, Your two missing MSD LEDs segment signals, F and A, are both carried by the wire jumpers to the top of the display board. Check the continuity from the F and A cathode segments back to the DR7. See message 56280 from Joe as it has a picture that shows the wires to the two MSD LEDs including the third B segment wire.
73
Roger VE7LB
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Murch did not try to claim it was his design but was a copy of the Ultimate Transmatch? by Lewis McCoy.
Murch just put it into production and there were several versions of it over the years.
While I am not sure, I think Murch made many of the components as they were hard to find.
Ralph ku4pt
On Sunday, March 21, 2021, 04:03:48 PM EDT, Steve Bookout, NR4M <steve@...> wrote:
None of us know everything.? ¡®Murch¡¯ is an old school brand of basic, well built, tuners.?
Much better, and beefier than many current tuners.?
73 de Steve, NR4M? On Mar 21, 2021, at 3:57 PM, Billy Pickering KO4INE <pickeringw@...> wrote:
?It's another brand of antenna tuner made by Murch Electronics.
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And here is a pic of my Murch. The new knobs nicely hide the holes from the mounting of the cheap junk verniers. 73 -Jim NU0C On Sun, 21 Mar 2021 15:38:52 -0500 "Jim Shorney" <jshorney@...> wrote: Yeah, it's sort of a dark gray. I thought maybe I had a pic of mine with the green knobs. I'll do that later.
I'm more of a function over form guy. It it does the job I don't care how it looks. In my case it matches a Hy-Gain Penetrator 500 from 10 through 12 Meters.
73
-Jim
NU0C
On Sun, 21 Mar 2021 13:32:51 -0700
"VE7PS" <ve7ps@...> wrote:
Jim:
You are right about the A model being green...or at least the cabinet
is.? Front panel looks like dark gray??? But maybe I have only ever seen
them in B & W QST's!!!? Not too many of those ever made it north of the
49th.
The B model appears to have been a gray hammertone cabinet, unless the
one I saw in an old Ebay listing has been painted.? Front panel looks
black in the pic I found.
Great tuner from all reports....but maybe not a good match for a Drake
4-line station, at least from a cosmetic standpoint.
PS
On 2021-03-21 1:23 p.m., Jim Shorney wrote:
Commercial version of Lew McCoy's "Ultimate Transmatch" described in the linked article. This is what mine looks like (except for the outer knobs).
73
-Jim
NU0C
On Sun, 21 Mar 2021 12:51:12 -0700
"Joe Wolfe" <w7rkn.7@...> wrote:
At the appearance of being incredibly dumb, what is a 'Murch'?
Joe - W7RKN
-----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf Of Jim Shorney
Subject: Re: [DRAKE-RADIO] MN2000
This is the tech behind the Murch. And also why you find homebrew variants.
73
-Jim
NU0C
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Mike Davidsohn G3ZCC
Jim Shorney
Ryan Scott
