Re: T-4XC diode CR1 question
Bill;
You won't regret purchasing the appropriate K4OAH documents for your Drakes.? They sure make it easier to find components.? They aren't perfect....there is no way Garey could cover detailed parts locations?for all versions of radios such as the R-4C, which had several major upgrades.? That said, he did include the various versions of the schematics wherever/whenever he could get them.
If you are seeing 120w out then the?+250 VDC line must be working fine.? Any slight chirp on the CW signal???
73 Peter VE7PS
Thanks Ken & Peter. Very helpful. The Tx seems to be operating ok- over 120 W out and no observed anomalies. It looks like it is time for me to order K4OAH's manual!
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Bill N0CU
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Perhaps the waterproof lights you selected were poor quality to begin with.? Here is a guide on the different products and IP ratings.
https://www.ledyilighting.com/a-guide-to-waterproof-led-strip-lights/
Doug, WA3DSP
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Re: T-4XC diode CR1 question
Thanks Ken & Peter. Very helpful. The Tx seems to be operating ok- over 120 W out and no observed anomalies. It looks like it is time for me to order K4OAH's manual!
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Bill N0CU
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Re: TR7 - PTT CLOSURE-TO-TX SIGNAL OUTPUT DELAY TIME?
Great responses, guys...many thanks.?
Doug WA3DSP: Your solution is definitely the fail-safe one. My SDR switch has both RF switching and audio switching/TX muting capabilities. I could very well just use the audio switch/mute feature with the internal T/R relay of the TR7 for the RF part. The wiring might get a wee bit hairy, as I was planning to use the RX output to drive a 6m transverter. But, it's nothing that some well-planned external switch boxes couldn't overcome.
Jim VE7RF: That is a very slick way of sequencing everything. I'll have to look and see if the TR7 has a TX inhibit line, or if I could easily add one to it. The beauty of your system is that one can add a simple, adjustable time constant to the delay relay PTT line, adding delay as needed before it trips and releases the TX inhibit.
Jeff AC0C: Is 2 mS the total time for PTT closure to output signal (including T/R relay closure, etc.), or is that just the rise time of the TX circuitry after it receives the PTT go-ahead??
73, Dennis W1LJ
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Re: T-4XC diode CR1 question
Bill:
C191 is the tantalum cap adjacent to CR1.? ?See pic from K4OAH's service manual.? And Ken's suggestion about ensuring the +250VDC line and R7 is OK is also good advice.? My bet is on the zener/tantalum though, depending on other symptoms.? Are you getting any power out of the rig at all?
73 Peter VE7PS
Peter, I was suspecting from the diode part number that it was probably a 13V device. Is C191 a tantalum? My read on the schematic is that it is one of the two electrolytics in the nearby can.
On Wed, Mar 8, 2023 at 11:44?AM VE7PS < ve7ps@...> wrote: Bill:
You should see about 13 VDC on that zener.? It's a 13V 1 watt zener.? Check the adjacent tantalum cap, C191.? I have seen these go bad...and take the zener with it!? Chirpy CW is sometimes the clue.
73 Peter VE7PS
This diode (Z-13B) is listed as a voltage regulator. The voltage I am seeing across this diode is only +1.2 volts, which seems unusually low. I don't recall ever seeing a Zener diode that goes below 3 volts. Searching the Internet, I couldn't find any info on this part. Is this the correct voltage for this part? If not, what should it be?
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Bill N0CU
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Re: T-4XC diode CR1 question
Peter, I was suspecting from the diode part number that it was probably a 13V device. Is C191 a tantalum? My read on the schematic is that it is one of the two electrolytics in the nearby can.
On Wed, Mar 8, 2023 at 11:44?AM VE7PS < ve7ps@...> wrote: Bill:
You should see about 13 VDC on that zener.? It's a 13V 1 watt zener.? Check the adjacent tantalum cap, C191.? I have seen these go bad...and take the zener with it!? Chirpy CW is sometimes the clue.
73 Peter VE7PS
This diode (Z-13B) is listed as a voltage regulator. The voltage I am seeing across this diode is only +1.2 volts, which seems unusually low. I don't recall ever seeing a Zener diode that goes below 3 volts. Searching the Internet, I couldn't find any info on this part. Is this the correct voltage for this part? If not, what should it be?
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Bill N0CU
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Re: T-4XC diode CR1 question
Bill,
In an older manual CR1 is listed as a Z-13B which is a 13V, 0.5W Zener. In a later manual I see CR1 listed as 1N4743A, 13V, W.
CR1 is the?voltage regulator for the carrier oscillator. It is fed via R7, a 5K, 20W resistor from the?+250VDC bus. If you are only?seeing? +1.2V then I would look at R7 as well at the?+250V bus.
? 
This diode (Z-13B) is listed as a voltage regulator. The voltage I am seeing across this diode is only +1.2 volts, which seems unusually low. I don't recall ever seeing a Zener diode that goes below 3 volts. Searching the Internet, I couldn't find any info on this part. Is this the correct voltage for this part? If not, what should it be?
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Bill N0CU
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Re: T-4XC diode CR1 question
Bill:
You should see about 13 VDC on that zener.? It's a 13V 1 watt zener.? Check the adjacent tantalum cap, C191.? I have seen these go bad...and take the zener with it!? Chirpy CW is sometimes the clue.
73 Peter VE7PS
This diode (Z-13B) is listed as a voltage regulator. The voltage I am seeing across this diode is only +1.2 volts, which seems unusually low. I don't recall ever seeing a Zener diode that goes below 3 volts. Searching the Internet, I couldn't find any info on this part. Is this the correct voltage for this part? If not, what should it be?
--
Bill N0CU
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This diode (Z-13B) is listed as a voltage regulator. The voltage I am seeing across this diode is only +1.2 volts, which seems unusually low. I don't recall ever seeing a Zener diode that goes below 3 volts. Searching the Internet, I couldn't find any info on this part. Is this the correct voltage for this part? If not, what should it be?
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Bill N0CU
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Re: DX Engineering LC-2-T4X Speech Processor
I used to use one of these years ago with my Drake gear, as needed. ?When used as directed, it increased talk power without adding distortion.
73,
Evan, K9SQG
-----Original Message-----
From: Steve Wedge, W1ES/4 via groups.io <w1es@...>
To: [email protected]
Sent: Wed, Mar 8, 2023 7:49 am
Subject: Re: [DRAKE-RADIO] DX Engineering LC-2-T4X Speech Processor
I thought that it looked like yours.
Steve Wedge, W1ES/KP2
Time flies like an arrow. Fruit flies like a banana.
Sent from Proton Mail for iOS
On Wed, Mar 8, 2023 at 06:33, Bill Losef via groups.io < w.losefsky@...> wrote:
Denis,
These work great and definitely enhances the transmitted audio signal. I have one!
On Wednesday, March 8, 2023 at 02:43:57 AM EST, Denis Sharon <denissharon@...> wrote:
Here is a DX Engineering LC-2-T4X Speech Processor for T-4X, A and C transmitters. It is a highly regarded addition to 4 series transmitters that is easily installed and readily reversible. It is in excellent condition and I?have no reason to believe it won¡¯t operate perfectly but don¡¯t have a 4 series transmitter and have no means to test it. Price is $150 shipped CONUS.?
Regards,?
Denis Sharon ?W1WVA?
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Re: DX Engineering LC-2-T4X Speech Processor
I thought that it looked like yours.
Steve Wedge, W1ES/KP2
Time flies like an arrow. Fruit flies like a banana.
Sent from Proton Mail for iOS
On Wed, Mar 8, 2023 at 06:33, Bill Losef via groups.io < w.losefsky@...> wrote: Denis,
These work great and definitely enhances the transmitted audio signal. I have one!
On Wednesday, March 8, 2023 at 02:43:57 AM EST, Denis Sharon <denissharon@...> wrote:
Here is a DX Engineering LC-2-T4X Speech Processor for T-4X, A and C transmitters. It is a highly regarded addition to 4 series transmitters that is easily installed and readily reversible. It is in excellent condition and I?have no reason to believe it won¡¯t operate perfectly but don¡¯t have a 4 series transmitter and have no means to test it. Price is $150 shipped CONUS.?
Regards,?
Denis Sharon ?W1WVA?
|
Re: DX Engineering LC-2-T4X Speech Processor
Denis,
These work great and definitely enhances the transmitted audio signal. I have one!
On Wednesday, March 8, 2023 at 02:43:57 AM EST, Denis Sharon <denissharon@...> wrote:
Here is a DX Engineering LC-2-T4X Speech Processor for T-4X, A and C transmitters. It is a highly regarded addition to 4 series transmitters that is easily installed and readily reversible. It is in excellent condition and I?have no reason to believe it won¡¯t operate perfectly but don¡¯t have a 4 series transmitter and have no means to test it. Price is $150 shipped CONUS.?
Regards,?
Denis Sharon ?W1WVA?
|
DX Engineering LC-2-T4X Speech Processor
Here is a DX Engineering LC-2-T4X Speech Processor for T-4X, B and C transmitters. It is a highly regarded addition to 4 series transmitters that is easily installed and readily reversible. It is in excellent condition and I?have no reason to believe it won¡¯t operate perfectly but don¡¯t have a 4 series transmitter and have no means to test it. Price is $150 shipped CONUS.?
Regards,?
Denis Sharon ?W1WVA?
|
Re: TR7 - PTT CLOSURE-TO-TX SIGNAL OUTPUT DELAY TIME?
The rise time of some TR7 is almost instant - under 2 mS.? So if
there is any hope, it will be on the PTT to the RF ramp.? Because
the typical TR7 has a fantastically high RF ramp - once it gets
going.
73/jeff/ac0c
alpha-charlie-zero-charlie
On 3/7/2023 11:44 PM, Jim VE7RF wrote:
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Show quoted text
No clue.? But the method the arrl lab uses is as following.?
?They apply a tone to the mic jack.? ?Then key the PTT /
footswitch,? and synced to scope.? Then state how many msecs to
reach 1/2 normal power output.? I find that data a bit flaky at
best.? They should graph it all out.? IE:? power output? vs 0-20
msecs? etc.? My MK-V takes 11 msecs to get to half power ( 100
watts is 1/2 power).? Nice to know, but how much po after say
1-3 msecs ?? ?I don't want any po for the 1st 5 msecs at least.?
To sequence things right in the L4B? with it's vac relays and
also the hb amps,? I had to use the TX inhibit lead in the
MK-V...so PO comes out of the xcvr...dead last.? I used the oem
spst relay in the mk-v (intended to key an amp)? to grnd the TX
inhibit lead on the yaesu mk-v.? That relay takes 5 msecs to
operate.? That gives the vac relays a? 5 msec? head start.? The
oem 3pdt TR relay in the L4B takes 17 msecs to operate.? ?They
were replaced with sped up vac relays.??
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Re: TR7 - PTT CLOSURE-TO-TX SIGNAL OUTPUT DELAY TIME?
Doesn't the TR7 have a outboard receive capability. There is a jumper between the two RCA connectors on the back. See your manual. Mine has the internal jumper removed and the two RCA jacks jumpered with a short piece of coax. Just cut the inside jumper if it exists and connect the SDR to the receive RCA jack. This is switched by the TR7 antenna relay, so no worry of RF to the SDR.
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Doug, WA3DSP
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Re: TR7 - PTT CLOSURE-TO-TX SIGNAL OUTPUT DELAY TIME?
No clue.? But the method the arrl lab uses is as following.? ?They apply a tone to the mic jack.? ?Then key the PTT / footswitch,? and synced to scope.? Then state how many msecs to reach 1/2 normal power output.? I find that data a bit flaky at best.? They should graph it all out.? IE:? power output? vs 0-20 msecs? etc.? My MK-V takes 11 msecs to get to half power ( 100 watts is 1/2 power).? Nice to know, but how much po after say 1-3 msecs ?? ?I don't want any po for the 1st 5 msecs at least.?
To sequence things right in the L4B? with it's vac relays and also the hb amps,? I had to use the TX inhibit lead in the MK-V...so PO comes out of the xcvr...dead last.? I used the oem spst relay in the mk-v (intended to key an amp)? to grnd the TX inhibit lead on the yaesu mk-v.? That relay takes 5 msecs to operate.? That gives the vac relays a? 5 msec? head start.? The oem 3pdt TR relay in the L4B takes 17 msecs to operate.? ?They were replaced with sped up vac relays.??
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I have one of those that I used when tracing wiring on Navy fighter jets. I broke it out again when I got my TR7.? Has proved to be very useful.
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Speaking of testing 6JB6's....?
See attached PDF
This "Tester for 6146 tubes" just came up in a post to the Collins Collectors group forum for testing and matching 6146's.
Perhaps one of the tube manual guru's/engineers can modify this circuit and it would be another option to test and match 6JB6's?
Conceptually it looks pretty simple.
- Steve W7SJT
"Always look for a positive solution then Improvise, Adapt, and Overcome" - adaptation of the U.S. Marine Corps motto "Every day is an opportunity to challenge the achievement of your dreams"
"Success is not final, failure is not fatal.? It is the courage to continue that counts."
-?Winston Churchill
?
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Re: Drake TR-7 digital display vers analog VFO differences
Peter ¨C you may have sent this to the wrong Terry. I don¡¯t own a TR-7 currently. (but wouldn¡¯t mind having one ha ha.) on the positive side, I don¡¯t have any edge connector problems.
toggle quoted message
Show quoted text
On Mar 7, 2023, at 08:27, VE7PS <ve7ps@...> wrote:
? Terry:
Sent this to the list just a few weeks back....? You need to determine if the digital dial is the correct one first.....Probably is.
73 Peter VE7PS
I'll be quick to point out that I am not as familiar with the nuances of the TR-7 PTO as those in the 4-line radios - haven't had to be, fortunately!? Jim, Steve, or Joe may have better ideas on this one than I do, but this has worked for me.
If it's the 5 khz dial (front dial) that is off, and the rubber bushing behind the dial isn't in too bad shape, you should be able to hold the plastic tuning knob still with one hand, and rotate the chrome skirt behind it to reset the 5 khz dial.
If it's the 100 khz dial that is off.....it's way more work, as far as I know.? I have done this a few times in the past;
Take the top cover off.? Let the radio warm up for an hour or two.? Set it at exactly any 100 Khz point on the digital dial, and record which one you set it to.? Turn the radio off and remove the DR-7 digital display board (you can find how to do that elsewhere in the archives.? DON'T BUMP THE TUNING KNOB!
With the radio facing you, release the steel "lever" that releases the idler gear from the gear train.? It's on the right upper corner?of the PTO.??Again, keep the PTO from moving.? With one hand holding the tuning knob still, rotate the 100 Khz dial (rear dial) to the 100 khz setpoint you wrote down.? If the 5 khz dial moves slightly too, try and hold it still with your 3rd hand (!) - you can set it as above later. if necessary. Carefully release the lever so the idler gear re-engages the gear train.? You may have to rock the tuning knob slightly to make that happen.? Repeat as necessary to get the dial where you want it.? The trick is keeping the PTO from moving while you do all this!
Too bad Drake didn't design this radio with easier access to that adjustment?with the DR-7 in place?and giving you a display.? I suppose you could hook up a frequency counter to the PTO and monitor that while you do it - will have to try that, if there is a "next time".
73 Peter VE7PS
Good Morning,
Picked up Drake TR-7 Ham Fest special couple weeks ago for
parts but had to see if I could bring it back to life. Got it up and running
then noticed the digital display differs 23 KHZ from the VFO read out. The TR-7
receives and transmits on correct frequency using the digital display. I
don¡¯t seem to find how to correct this in the service manual? My first
thought was it must have a set screw to align VFO disks. Or do I warp the
digital display over to the VFO displayed.
Thanks,
Terry KF0HR in North Dakota
?
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Re: 6JB6 Tube Tester Adapter
I have just ?received another batch of 20 PCBs for this project. ?
Price is US $7.00 including postage to North America.
Please contact me off list, if you want one.
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73, Bernie. VE3FWF
Real?radios glow in the dark
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Doug Crompton WA3DSP
Ham Radio