FS-TR7 Transmit Exciter Board
I have a TR7 transmit exciter board for sale that be of use to someone.
I purchased it from K3ICH some time ago but no longer need it as I am selling the TR7, serial 4566.
If interested please contact me off line at? hpolkscw@....
Harold
N3HP
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Re: Drake UV-3 DEAF receiver FIXED!!
Paul
The teflon coax is rather robust. I don’t have a clue as to why it may have shorted out. IT could have been a manufacturing defect when they overheated the braid when soldering it to the pcb. Teflon is normally very tolerate of high temps. Perhaps we’ll never know.
Way back when, I built a Heathkit HW2026A. It worked great mobile in my neck of the woods, we’re kinda rural here, but when you got within twenty miles of Columbus Ohio, that radio would howl, squeak and buzz due to the high powered pager transmitters. The cure? Turn the radio off until you got out of Columbus.
As for the PL, I found a Communications Specialist PL black box. I don’t recall the model number. It has a rotary switch on the front so you can dial up the PL needed. I picked it up at a hamfest for a few bucks. All three local repeater have the same PL, so I set it and don’t mess with it.
I purchased a small PL encoder for one of my Drake TR33s and I got it off of eBay for about $30. It’s set and forget one tone (you of course decide what tone you want) I might get another one for this UV3.
There are two more UV3s in the pile. They both have a full RF board decks. One has no receive whatsoever, but it does transmit. The other….it’s got lots of issues. One, it won’t key when I press the PTT on the mic, yet I can use a clip lead and ground the TX pin on the mic connector (chassis) and the receiver mutes, no TX relay action. Yeah, I tried more than one mic.?
BUT!!!
If you clip the TX pin low with the clip lead and rotate the band switch, whoa! you get power (22W) on 140 module. ditto the same on the other modules.
I live in the shadow of the locale repeater, and even into a dummy load at 1W or less, I can key it up. There are no 220 repeaters, and the 440 repeaters use a digital PL that I can’t produce. I’m thinking these two UV3s might end up on eBay.?
Again, thanks for your help in getting these old radios back on the air.
73 Mike wb8vge
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On Feb 10, 2024, at 7:50 PM, Paul N2NMI via < pdulaff@...> wrote:
Hi Mike Good work. Just a shorted coax, go figure. Was it the aspect of long term teflon creep that let those sharp shield wire strands work there way thru the dielectric ? Those measurements are very good. Receiver is as hot as a pistol, as good as repeater receivers measure. Looks like 5 or 6 poles total in the front end so very good for intermod for a (at the time) mobile multiband rig. Had my 2M single bander in the car when I commuted and would work 146.52 simplex along the long 80 mile commute. Rig was 35 years old then and never missed a beat. Was working a ham 60+ miles away on 146.52 simplex with me being mobile and a 5/8 wavelength mag mount on the roof. No amp, just the rigs 25 watts. I could copy him when I was crossing the Tappanzee Bridge NY and the other station was just north of Atlantic City NJ. What are you using for PL on the UV3's ? Paul - W2NMI
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Re: Another TR7 Journey begins
Jim,
No way I'm going to use regular DeOxit!? I'm planning to devote tomorrow to working on the TR-7 so hopefully I can find the issue.
73, Bill NX0T
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Re: All bent out of shape (3-500z)
This is a common problem of rough handling.? That is why it was ALWAYS said to never lay the Eimac tubes on the side, always standing up and to treat them like fine crystal. Vince N8MQV ?
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From: [email protected] < [email protected]> On Behalf Of David Sent: Sunday, February 11, 2024 7:53 AM To: [email protected]Subject: Re: [DRAKE-RADIO] All bent out of shape (3-500z) ? Yes.? Looks like the bottom end of the plate assembly.? Have seen this before.? For the one I saw the crimp/ weld at the top of the plate was either broken or twisted by damage.? Perhaps by too fast of motion and then an abrupt stop. This is not a good tube.? Compate this to a new Eimac or GE tube and you will see a different structure at the top of the plate. David Assaf III
W5XU??? VP8RXU ? On Sat, Feb 10, 2024, 9:37 PM Jim Shorney <jimNU0C@...> wrote:
OK guys, have a look at this close-up pic of a 3-500z. This was found in an L7 (not mine). That's not lens distortion or an optical illusion, it really looks like that. makes noise when you pick it up and move it around. This LOOKS like brand new tube. As does its partner. 93xx date codes, paint that looks fresh and not burned. I can't figure how this got out of the factory this way but it doesn't look like shipping damage to me. The wonky tube has a yellow dot sticker on top like someone knew...? Wow. The moral of this story is always give unknown tubes a good look before you power them up. I hate to think of what would have happened if I had hit this one with full HV.
--
73
-Jim
NU0C
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Re: All bent out of shape (3-500z)
Yes.? Looks like the bottom end of the plate assembly.? Have seen this before.? For the one I saw the crimp/ weld at the top of the plate was either broken or twisted by damage.? Perhaps by too fast of motion and then an abrupt stop. This is not a good tube.? Compate this to a new Eimac or GE tube and you will see a different structure at the top of the plate.
David Assaf III
W5XU??? VP8RXU
On Sat, Feb 10, 2024, 9:37 PM Jim Shorney < jimNU0C@...> wrote:
OK guys, have a look at this close-up pic of a 3-500z. This was found in an L7 (not mine). That's not lens distortion or an optical illusion, it really looks like that. makes noise when you pick it up and move it around. This LOOKS like brand new tube. As does its partner. 93xx date codes, paint that looks fresh and not burned. I can't figure how this got out of the factory this way but it doesn't look like shipping damage to me. The wonky tube has a yellow dot sticker on top like someone knew...? Wow. The moral of this story is always give unknown tubes a good look before you power them up. I hate to think of what would have happened if I had hit this one with full HV.
--
73
-Jim
NU0C
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Re: All bent out of shape (3-500z)
The weird part is the rod doesn't look bent and there is no stuff loose inside the envelope. That's the first thing I looked for. I wouldn't think that the plate structure has enough mass to bend that thick rod that much, but maybe. And who put the yellow dot on it and stuck it the amp? The current owner wasn't even sure there were tubes in it, he sent along a set of new Chinese tubes for it. 73 -Jim NU0C On Sun, 11 Feb 2024 03:59:06 +0000 (UTC) "Evan via groups.io" <k9sqg@...> wrote: Jim,
I have a similar one too. ?The plate "stud" or rod was bent due to excessive force during shipping. ?Typically there will also be some flakes of the grid floating around too if the tube is not new.
Getting an insurance claim settled was quite a saga.
73,
Evan
On Saturday, February 10, 2024 at 10:37:19 PM EST, Jim Shorney <jimnu0c@...> wrote:
OK guys, have a look at this close-up pic of a 3-500z. This was found in an L7 (not mine). That's not lens distortion or an optical illusion, it really looks like that. makes noise when you pick it up and move it around. This LOOKS like brand new tube. As does its partner. 93xx date codes, paint that looks fresh and not burned. I can't figure how this got out of the factory this way but it doesn't look like shipping damage to me. The wonky tube has a yellow dot sticker on top like someone knew...? Wow. The moral of this story is always give unknown tubes a good look before you power them up. I hate to think of what would have happened if I had hit this one with full HV.
-- 73 -Jim NU0C
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Re: All bent out of shape (3-500z)
Jim,
I have a similar one too. ?The plate "stud" or rod was bent due to excessive force during shipping. ?Typically there will also be some flakes of the grid floating around too if the tube is not new.
Getting an insurance claim settled was quite a saga.
73,
Evan
On Saturday, February 10, 2024 at 10:37:19 PM EST, Jim Shorney <jimnu0c@...> wrote:
OK guys, have a look at this close-up pic of a 3-500z. This was found in an L7 (not mine). That's not lens distortion or an optical illusion, it really looks like that. makes noise when you pick it up and move it around. This LOOKS like brand new tube. As does its partner. 93xx date codes, paint that looks fresh and not burned. I can't figure how this got out of the factory this way but it doesn't look like shipping damage to me. The wonky tube has a yellow dot sticker on top like someone knew...? Wow. The moral of this story is always give unknown tubes a good look before you power them up. I hate to think of what would have happened if I had hit this one with full HV.
--
73
-Jim
NU0C
|
All bent out of shape (3-500z)
OK guys, have a look at this close-up pic of a 3-500z. This was found in an L7 (not mine). That's not lens distortion or an optical illusion, it really looks like that. makes noise when you pick it up and move it around. This LOOKS like brand new tube. As does its partner. 93xx date codes, paint that looks fresh and not burned. I can't figure how this got out of the factory this way but it doesn't look like shipping damage to me. The wonky tube has a yellow dot sticker on top like someone knew... Wow. The moral of this story is always give unknown tubes a good look before you power them up. I hate to think of what would have happened if I had hit this one with full HV.
--
73
-Jim
NU0C
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Does anyone have a RV7 front panel they are willing to sell?
73
Stan
KM4HQE
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Re: Drake UV-3 DEAF receiver FIXED!!
Hi Mike
Good work. Just a shorted coax, go figure. Was it the aspect of long term teflon creep that let those sharp shield wire strands work there way thru the dielectric ? Those measurements are very good. Receiver is as hot as a pistol, as good as repeater receivers measure. Looks like 5 or 6 poles total in the front end so very good for intermod for a (at the time) mobile multiband rig. Had my 2M single bander in the car when I commuted and would work 146.52 simplex along the long 80 mile commute. Rig was 35 years old then and never missed a beat. Was working a ham 60+ miles away on 146.52 simplex with me being mobile and a 5/8 wavelength mag mount on the roof. No amp, just the rigs 25 watts. I could copy him when I was crossing the Tappanzee Bridge NY and the other station was just north of Atlantic City NJ. What are you using for PL on the UV3's ?
Paul - W2NMI
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Re: Drake UV-3 DEAF receiver FIXED!!
Good on you!? Great Sleuthing! David Assaf III W5XU, VP8RXU ?
On Sat, Feb 10, 2024 at 5:11?PM Mike Bryce < prosolar@...> wrote: Paul and group…
I have said it in the past that I’m no RF engineer. However I am persistent.
It made no sense to me why the receiver should be so deaf when nothing was staring me in the face. All of the transistor voltages were just about spot on.
As Paul suggested, I too thought maybe the pin diode CR301 might be shorted or very leaky. Turns out it was fine.
What else could it be?
To paraphrase an old sleuth, Mister Sherlock Ohms;
“After you eliminate the impossible, whatever is left, however improbable, must be the truth.”
So went back to the beginning and in this case that was the input to the receiver. The input does show continuity to ground, because there is a inductor ?(L1504) connected directly to the antenna connector. I checked this before, and decided it was normal.
However when I re-visited this, I removed the inductor, easy to do by taking out a nut and screw.?
And the ground remained! The bloody input was shorted to ground. No wonder the receiver couldn’t hear a thing.
To condense this rather long story down, the problem with the deaf receiver was traced down to a 2” piece of miniature coax that connects the T/R relay to the 140 board front end. Apparently, over time, a couple of sharp braid wires managed to punch through the teflon insulator and short out the coax, and with the antenna at DC ground, it was simply overlooked.?
The UV3 can now hear a .06 uV signal and .14 uV opens the squelch.? With .3 uV, the meter deflects a bit.
Sometimes the birds do sing.
A special call out and thanks to Paul, W2NMI, for all his help in describing how this beastie works. Paul, I owe you a beer!
Mike, WB8VGE
A man with one clock knows what time it?is. A man with two clocks is never sure.
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Re: Drake UV-3 DEAF receiver FIXED!!
Paul and group…
I have said it in the past that I’m no RF engineer. However I am persistent.
It made no sense to me why the receiver should be so deaf when nothing was staring me in the face. All of the transistor voltages were just about spot on.
As Paul suggested, I too thought maybe the pin diode CR301 might be shorted or very leaky. Turns out it was fine.
What else could it be?
To paraphrase an old sleuth, Mister Sherlock Ohms;
“After you eliminate the impossible, whatever is left, however improbable, must be the truth.”
So went back to the beginning and in this case that was the input to the receiver. The input does show continuity to ground, because there is a inductor ?(L1504) connected directly to the antenna connector. I checked this before, and decided it was normal.
However when I re-visited this, I removed the inductor, easy to do by taking out a nut and screw.?
And the ground remained! The bloody input was shorted to ground. No wonder the receiver couldn’t hear a thing.
To condense this rather long story down, the problem with the deaf receiver was traced down to a 2” piece of miniature coax that connects the T/R relay to the 140 board front end. Apparently, over time, a couple of sharp braid wires managed to punch through the teflon insulator and short out the coax, and with the antenna at DC ground, it was simply overlooked.?
The UV3 can now hear a .06 uV signal and .14 uV opens the squelch. ?With .3 uV, the meter deflects a bit.
Sometimes the birds do sing.
A special call out and thanks to Paul, W2NMI, for all his help in describing how this beastie works. Paul, I owe you a beer!
Mike, WB8VGE
A man with one clock knows what time it?is. A man with two clocks is never sure.
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Re: Drake UV-3 DEAF receiver
Hi Mike. Looking at the IF/Discriminator/Audio board schematic, a 10.7 Mhz, 3 mv RF level (signal generator input) at the input side of the pin diode CR301 will produce 100 mVp-p at the drain side of Q300. This may be an easy, useful sanity check for confirming if the back end after the mixer is meeting spec. The first callout is somewhat unclear as these signal level callouts from Drake have been expressed as Peak to Peak. The 3 mv input level is labeled as "signal generator", thus would be Vrms. Hypothesis - could be a bad leaky pin diode (CR301, one example) or the diode not fully forward biased and attenuating signal or some other flaw in the back end ?
Paul - W2NMI
?
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Re: Drake TR-7 - A repair journey
To the group:
I made three corrections to the TR-7 Parent Board pinout docs and posted the updated Excel file and PDF file to the files section here:
The older version of the files have been deleted to conserve space.
Thanks again to Jim Shorney for catching the errors.
73, Tom, AG9X
On Thu, Feb 8, 2024 at 3:33?PM Jim Shorney < jimNU0C@...> wrote:
I can relate to that Tom. It does seem that no matter how many times I proof something I still miss things too often. I hope if anyone spots any errors in my stuff they will let me know. Thanks for all that you do.
73
-Jim
NU0C
On Thu, 8 Feb 2024 15:20:48 -0600
"Tom Evans" <Tom.AG9X@...> wrote:
> Thanks for catching the errors in the parent board pinout doc.? No matter
> how many times a person rechecks something, a different pair of eyes can
> spot unseen errors.
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Re: Drake UV-3 DEAF receiver
Hi Mike. This case is measuring well past scope's 3 db point. Expected then the scope would report a lower value than actual in this case. Simple way then is to compare the output at T800 (transmitter RF in) at 2.8 Vp-p to the receiver mixer LO input value of 4.0 Vp-p. The transmit level looks to be nearly correct given the transmitter power, so can then use that value of drive as a baseline to determine if the LO injection at the mixer is reasonable. If Q813 is suspect, need to look at the drain side and see if the scope can display the clipping of the LO drive.?
Paul - W2NMI
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Re: Drake UV-3 DEAF receiver
Hi Paul and the gang.
I think I may have done a serious measurement error! While this didn’t fix the problem with the deaf receiver, it has laid down a different avenue for me to take.
I measured 210mv at the source of Q813. That’s not even close to the 4.00 V pp as per the schematic.
However this morning, it dawned on me that I had the scope’s probe in the 10X position so it won’t load down the circuit. So my 210mV should be 2.10Vpp.
That however is only half the required signal level.
So I’m back to square one, and the lack of LO signal to the mixer.
Mike Bryce wb8vge
"The eye is always caught?by the light, but shadows?have more to say"
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On Feb 9, 2024, at 11:50 PM, Paul Dulaff via < pdulaff@...> wrote:
Hi Mike. So looking at the transmit power out of 18 watts vs the spec of 25 watts the rig is only slightly down in transmit power. Assuming the small drop is all drive from the VCO board, this is -1.43 db down. Using this, the output voltage at T800, instead of being 2.8 Vp-p, this voltage is 2.4 V p-p. Knowing this and using the scope, this voltage being measured with a scope with rolloff, can be used to gage the scope response at 146 Mhz and a tool to check the injection level at the mixer.
The receiver should be closer to 0.3 uV sensitivity than the measured 3 uV. So the receiver looks down at least 20 db as compared to the transmitter at 1.43 db. Seems then this issue would be Q811, Q813 section where the bigger issue exists. Now, mixers aren't linear devices so this is an imperfect comparison. The 4 Vp-p signal at the source of Q813 is substantially all local oscillator signal. Assume 20db gain at the RF Amp and we have 30 uV at the gate of Q813 with 3 uV input. Looking at the drain side of Q813 with the scope, you should see a clipped version of the local oscillator signal with gain. The Q813 device to be good mixer needs to be driven into saturation so that LO signal at the drain side (mixer output) should look like a hard clipped version of the sinusoidal signal at the source. The signal at the drain will be lower level as compared to the source as the IF input tank circuit C840/L801 is tuned to 10.7 Mhz with the LO at something like 135 Mhz. If little or no clipping exists, then low drive or Q813 JFET source or Q813 has issues as can be evidenced by no hard clipping of the LO signal at the drain.
Paul - W2NMI
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Does anyone have the adjustment/ alignment procedures for the Drake MN4?? Repaired the meter, but the readings are incorrect.
many thanks.
David Assaf III W5XU, VP8RXU ?
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Re: Another TR7 Journey begins
On Sat, 10 Feb 2024 06:55:52 -0800 "Bill NZ0T" <nz0tham@...> wrote: Got the PS working and it was mostly pilot error.? The previous owner had replaced the Jones connector on the DC cord with Molex connectors for whatever reason and had put PowerPoles on the Jones connector.. The devil is in the details... :D So that leaves the very low sidetone volume, no forward/reflected power on the meter and the wonky ALC to fix before I put the rig on the air.? I'm wondering if the ALC pot on the ALC board migt be dirty or bad.? I may try a shot of DeOxit to see if that helps.
Any suggestions are greatly appreciated! Again, do not use DeOxit on pots. Use a cleaner that is designed specifically for pots, like Faderlube. Or just clean the entire ALC board with alcohol. Drake liked high impedance circuits and crud accumulation on boards can sometimes throw things off. -- 73 -Jim NU0C
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Re: Another TR7 Journey begins
Got the PS working and it was mostly pilot error.? The previous owner had replaced the Jones connector on the DC cord with Molex connectors for whatever reason and had put PowerPoles on the Jones connector..? And for whatever reason I was thinking he had somwhow added that line so I only had to use the other connector for everything.? I finally actually looked at the photo of the PS in the owners manual I downloaded and realized that BOTH cables had to be connected - DUH!? So I cut off the Molex conectors, replaced them with the orginal Jones connector, plugged both into the rig and guess what - it worked!
So that leaves the very low sidetone volume, no forward/reflected power on the meter and the wonky ALC to fix before I put the rig on the air.? I'm wondering if the ALC pot on the ALC board migt be dirty or bad.? I may try a shot of DeOxit to see if that helps.
Any suggestions are greatly appreciated!
73, Bill NZ0T
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Re: Added photo album Drake R-4C T-4XC and MS-4 Powersupply
#photo-notice
Dwight,
You didn’t give info on who is selling, seller’s contact info, and price. ?When you have a moment please post that information. ? 73, Bill KJ5BNE ++++++++++++++++ Bill Blodgett Arlington, Texas
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On Feb 9, 2024, at 11:47?PM, Group Notification <[email protected]> wrote:
?
dwight_talley <dwight_talley@...> added the photo album
Drake R-4C T-4XC and MS-4 Powersupply
: For sale are a complete set of Drake Receiver, Transmitter and Supply /Speaker
From the estate of a Ham. The receiver is very sensitive and sounds good. I am unable to test the transmitter but it does powerup without issue.
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David
Jim Shorney
