Progress on repairing my RV75 has come to a halt. In attempting to perform the alignment procedure in the Operator’s Manual, I have discovered that the VCXO is not oscillating. The VCXO is a voltage controlled crystal oscillator which uses a varactor diode to “pull” a 15.5 MHz crystal oscillator frequency to provide fine tuning for the PLL. Without the signal from this oscillator the PLL will not lock and stabilize the RV75 output frequency.
The VCXO circuitry is somewhat complex and is implemented entirely with discrete components including several semiconductors, a 15.5 MHz crystal, a varactor diode, three variable inductors, and numerous resistors and axial lead ceramic capacitors of the type that were found failed elsewhere on the RF & Analog board. I have visually inspected this circuit under a magnifier and have checked several voltages but have so far not been able to identify a reason why the VCXO is not working. Given the number of components involved and without any clear indication of a component failure, it makes no sense to me to start replacing components, some of which may be available only by salvaging from another RV75 RF & Analog board.
My best current idea for a fix is to send the RV75 off to someone who knows this device far better than I do; apparently wishful thinking on my part as I have been unable to identify someone who both fits this description and is willing to take on this repair. So, for now I will put the RV75 back on the shelf while I turn my attention to other projects and give some background thought to how best to proceed. This is disappointing in that this RV75 is in excellent cosmetic condition, and I have been able to verify that it is apparently working as it should otherwise.
I am still interested in purchasing RV75 repair parts, including a working RF & Analog board, VCXO crystal, VCXO variable inductors, etc. should someone on this forum have these available.
Interesting footnote: An RV75 has been listed on eBay over the last few days for an auction sale, with the auction ending last night. This unit was described as “not working, for parts or repair” and appeared to be in very rough cosmetic condition in the single photo posted. I decided to monitor the bidding on this item for the last five minutes of the auction. When I tuned in there were about seven bids, with the highest at $150. From prior experience on eBay I knew that the real bidding excitement would likely come in the last few seconds of the auction. I wasn’t disappointed. In the last three seconds, two bids were posted, one at $450, and the final bid at $477. Madness!
Rick
K8EZB
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Re: All bent out of shape (3-500z) - now shock sensor value question
On Tue, Feb 13, 2024 at 01:57 AM, Joe - W7RKN wrote:
<When we purchase shipping insurance through whomever, they will always tell you to submit an invoice for the product loss.? I tell them, nuts to you…I paid for 500 dollars of insurance, cut me a check for 500 dollars.? I took UPS to court on <this a number of years ago and won.? Just an FYI!
##? You can't insure it for more than it's worth.?
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Re: All bent out of shape (3-500z) - now shock sensor value question
I use 25g or 50g rated sensors, depending on the weight and value of the package. ? These are the most inexpensive, each, but shipping adds to the cost.
? Amazon has ShockWatch….very expensive.
? As does Grainger:
Also expensive.. ? However, they are cheap if they save your shipped product! One more thing, while I am at it: ? When we purchase shipping insurance through whomever, they will always tell you to submit an invoice for the product loss.? I tell them, nuts to you…I paid for 500 dollars of insurance, cut me a check for 500 dollars.? I took UPS to court on this a number of years ago and won.? Just an FYI! ? Joe – W7RKN ? From: [email protected] [mailto:[email protected]] On Behalf Of Steve Toth via groups.io
Subject: Re: [DRAKE-RADIO] All bent out of shape (3-500z) - now shock sensor value question ? This may be a dumb question, but what is a "typical common sense" value of shock sensor to use when shipping radio equipment?? I have to ship my ICOM 706MKiiG in for repair.
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Re: All bent out of shape (3-500z) - now shock sensor value question
This may be a dumb question, but what is a "typical common sense" value of shock sensor to use when shipping radio equipment?? I have to ship my ICOM 706MKiiG in for repair.
Thanks.
- Steve? W7SJT
"Always look for a positive solution then Improvise, Adapt, and Overcome" - Adaptation of the U.S. Marine Corps motto
"There are no rules here!...We're trying to accomplish something!!"
- Thomas Edison
"Success is not final, failure is not fatal.? It is the courage to continue that counts." -?Winston Churchill
?
On Monday, February 12, 2024 at 09:31:26 AM MST, Joe - W7RKN <w7rkn.7@...> wrote:
Shock sensors on and in the shipment would have removed any and all resistance to the claim by FedEx. Anything of value I ship, has shock sensors, inside and outside the box/shipping container.? To prevent the removal of the sensor, I put it on, outline it with a marks-a-lot then tape over it.? Then take a picture of it on the box.? I have had them removed.? The one inside shows what really happened.? I just tell the receiver that if the sensor is missing, video the opening of the carton, *while the delivery person* is still there, making sure he/she is in the vid.? If the inside sensor has been violated, and is missing on the outside of the box, the shipper will cringe at what will happen to them if the claim ever goes to court. ? Joe – W7RKN ? ? As a side note, insurance claims via FedEx for damaged tubes may or may not be honored. ? Why? ?With an amp and some tubes (packed separately, double boxed, well packed) that I sent out, there was damage. ?Come to find out that "what we don't ship" did not exclude vacuum tubes, only x-ray tubes and a few others. ?However, I also found out that vacuum tubes were listed under "what we don't insure", on their website. ?It was a battle and with the support of the shipper, pictures, specs about g forces for the 3-500Z, etc. the insurance claim was finally honored by FedEx. ?
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Re: Another TR7 Journey begins
The wattmeter circuit is pretty simple. There's not much that can fail. It is essentially the same as a W4. Put your meter on the FWD wattmeter and see if voltage goes up when you transmit power. If you see a sensible increase in voltage suspect the FWD/REF pushbutton or associated wiring. If you don't, meter the high side of pot R2001 on the back side of the Low Pass filter module and do the same. If you don't see voltage check the diodes in the meter circuit (CR2001 and 2002). If the diodes are good check that your transmit output is where it is supposed to be, not oscillating out of band and being absorbed by the low pass filter. You may also have a band switch, T/R relay, or low pass filter issue. The RS cleaner should be OK, but you will want to take precautions to ensure it doesn't spray everywhere. 73 -Jim NU0C On Mon, 12 Feb 2024 11:07:19 -0800 "Bill NZ0T" <nz0tham@...> wrote: [Edited Message Follows]
Hi Jim,
I really appreciate your help.? I was loking at the wrong PDF and the ALC board pic was so blurry I didn't see the label.? I was able to get the voltage down to around 0.5 VDC on a multimeter.? I don't have a VTVM but I'm pretty sure these new meters work OK for this.? The AC control on the ALC board is still extremely touchy and the Forward/Reflected power adjustments do nothing.? In both Forward and Reflected as selected by the pushbotton the panel the meter actually goes below zero.? I was able to get the S-meter set so I know the meter is OK.
So as far as I can tell the ALC is still not working properly.? Still think that control could be the problem.? I do have a can of the old Radio Shack control/contact cleaner and lubricant - wopuld that be OK to use on that control?
73, Bill NZ0T
-- 73 -Jim NU0C
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In light of the discussion regarding the shipment of transmitting tubes vs the apes at the shipping companies, I have a pair of Eimac 3-500Z's available for pickup only in the Greensboro/Raleigh-Durham area.? I had these in my L7 recently and wanted to make sure that they were good before offering them.? I had no trouble getting over a kW out of them in my L7.
I don't need two sets of tubes, so I'm offering these at $250 for the pair.? I will meet you within 50 miles or so of my home QTH in Graham, NC.
73,
Steve Wedge, W1ES/4
Time flies like an arrow.? Fruit flies like a banana.
Sent with secure email.
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Re: Another TR7 Journey begins
Hi Jim,
I really appreciate your help.? I was loking at the wrong PDF and the ALC board pic was so blurry I didn't see the label.? I was able to get the voltage down to around 0.5 VDC on a multimeter.? I don't have a VTVM but I'm pretty sure these new meters work OK for this.? The AC control on the ALC board is still extremely touchy and the Forward/Reflected power adjustments do nothing.? In both Forward and Reflected as selected by the pushbotton the panel the meter actually goes below zero.? I was able to get the S-meter set so I know the meter is OK.??
So as far as I can tell the ALC is still not working properly.? Still think that control could be the problem.? I do have a can of the old Radio Shack control/contact cleaner and lubricant - wopuld that be OK to use on that control?
73, Bill NZ0T
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Re: Another TR7 Journey begins
Look for the High Pass Filter Module schematic, Fig. 2-28. There is a list of illustrations in the front of the SM, page V. Page 2-80 is correct for the 1978 manual that I am looking at. I am aware that different revision manuals may have some slight variations in page numbering. I have no intent of researching that. You have all the information you need to find it. 73, -Jim NU0C On Mon, 12 Feb 2024 09:53:58 -0800 "Dale Parfitt" <PARINC1@...> wrote: Hi Jim,
Page 2-80 is a blank "Notes" page in my original Service manual notebook.
Dale W4OP
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Re: Another TR7 Journey begins
Hi Jim,
Page 2-80 is a blank "Notes" page in my original Service manual notebook.
Dale W4OP
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Re: All bent out of shape (3-500z)
The plate structures in all of these type tubes are fairly massive.? It was probably a side acceleration that actually moved it but I'm thinking that the plate "pin" might not be bent.? The plate structure appears to be tightly crimped and/or spot" welded to the pin
If the side acceleration was sufficient to break that spot weld or cause the crimped connection to loosen,? you could probably give it a little acceleration in the other direction to center the plate structure, but it would be forever "loose"?? (hence the "noise)
If it was enough acceleration to actually "bend" the pin, you could probably (carefully) "accelerate" it in the other direction to straighten it.?
It would be worth a try since the tube is now a science project anyway! Not much to lose here. (or "loose",? if you're in Rio Linda!!)
On Sat, Feb 10, 2024 at 07:37 PM, Jim Shorney 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
? --
73/Rick
W4XA
*Every post is created using Linux
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Re: All bent out of shape (3-500z)
Yup..I forgot to add that to the message! Thanks Jim!
Joe- W7RKN
toggle quoted message
Show quoted text
-----Original Message----- From: [email protected] [mailto: [email protected]] On Behalf Of Jim Shorney Subject: Re: [DRAKE-RADIO] All bent out of shape (3-500z) You must ship with signature required. Otherwise they just drop the package on your porch and run. 73 -Jim NU0C
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Re: TR-7 ALC Board Schematic
/g/DRAKE-RADIO/message/7607673 -Jim NU0C On Mon, 12 Feb 2024 08:47:22 -0800 "Dale Parfitt" <PARINC1@...> wrote: The service manual appears to skip over the ALC board schematic- or at least I am unable to find it.
Anyone enlighten me?
Tnx,
Dale W4OP
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The service manual appears to skip over the ALC board schematic- or at least I am unable to find it.
Anyone enlighten me?
Tnx,
Dale W4OP
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Re: All bent out of shape (3-500z)
You must ship with signature required. Otherwise they just drop the package on your porch and run. 73 -Jim NU0C On Mon, 12 Feb 2024 08:31:20 -0800 "Joe - W7RKN" <w7rkn.7@...> wrote: I just tell the receiver that if the sensor is missing, video the opening of the carton, *while the delivery person* is still there, making sure he/she is in the vid. -- 73 -Jim NU0C
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Re: Another TR7 Journey begins
The ALC board is part of the High Pass Filter module. You will find the schematic on page 2-80. The inputs are clearly labeled. ALC photo is page 2-73. There is a very early ALC board that is a little different but I have only heard of one confirmed in the field so I have no data on when the final version was put in production. 73 -Jim NU0C On Mon, 12 Feb 2024 07:58:28 -0800 "Bill NZ0T" <nz0tham@...> wrote: I am attempying to do the wattmeter null adjustment.? The service manual that I downloded from the files section says to connect a VTVM to the refected power input on the ALC board (see section 2-15).? I have read the description of the ALC board there several times but I can't figure out where that input is.? There is no schematic or photo of the board that I can look at - maybe a page is missing?? Anyone know where that point is on the ALC board?
73, Bill NZ0T
-- 73 -Jim NU0C
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Re: All bent out of shape (3-500z)
Shock sensors on and in the shipment would have removed any and all resistance to the claim by FedEx. Anything of value I ship, has shock sensors, inside and outside the box/shipping container.? To prevent the removal of the sensor, I put it on, outline it with a marks-a-lot then tape over it.? Then take a picture of it on the box.? I have had them removed.? The one inside shows what really happened.? I just tell the receiver that if the sensor is missing, video the opening of the carton, *while the delivery person* is still there, making sure he/she is in the vid.? If the inside sensor has been violated, and is missing on the outside of the box, the shipper will cringe at what will happen to them if the claim ever goes to court. ? Joe – W7RKN ? ? As a side note, insurance claims via FedEx for damaged tubes may or may not be honored. ? Why? ?With an amp and some tubes (packed separately, double boxed, well packed) that I sent out, there was damage. ?Come to find out that "what we don't ship" did not exclude vacuum tubes, only x-ray tubes and a few others. ?However, I also found out that vacuum tubes were listed under "what we don't insure", on their website. ?It was a battle and with the support of the shipper, pictures, specs about g forces for the 3-500Z, etc. the insurance claim was finally honored by FedEx. ?
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Re: Another TR7 Journey begins
I am attempying to do the wattmeter null adjustment.? The service manual that I downloded from the files section says to connect a VTVM to the refected power input on the ALC board (see section 2-15).? I have read the description of the ALC board there several times but I can't figure out where that input is.? There is no schematic or photo of the board that I can look at - maybe a page is missing?? Anyone know where that point is on the ALC board?
73, Bill NZ0T
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Re: All bent out of shape (3-500z)
As a side note, insurance claims via FedEx for damaged tubes may or may not be honored. ? Why? ?With an amp and some tubes (packed separately, double boxed, well packed) that I sent out, there was damage. ?Come to find out that "what we don't ship" did not exclude vacuum tubes, only x-ray tubes and a few others. ?However, I also found out that vacuum tubes were listed under "what we don't insure", on their website. ?It was a battle and with the support of the shipper, pictures, specs about g forces for the 3-500Z, etc. the insurance claim was finally honored by FedEx. ?
73,
Evan, K9SQG
On Monday, February 12, 2024 at 03:51:44 AM EST, Jim VE7RF <jim.thom@...> wrote:
<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
Tell that to UPS, Fedex,? USPS? etc.?
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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
Tell that to UPS, Fedex,? USPS? etc.?
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Drake Technical Net - 11 February 2024
The Drake Technical Net met at 21:00z on Sunday, 11 February 2024 ? There were 39 stations checking in with us, today. The Drake radios used included the following: ? >> Drake Twins (all models): 12 ? >> Drake TR-3 Transceivers: 0 ? >> Drake TR-4 Transceivers (all models): 10 ? >> Drake TR5 Transceivers: 1 ? >> Drake TR7 / TR7A Transceivers: 9 ? The net operated under fairly good conditions and did not close until 22:19z. ? Join us again on Sunday, 18 February 2024 at 21:00z (4:00 PM EST, 3:00 CST). Net Control will be Ron Baker, WB4HFN. ? 73, ? Bill Shadid, W9MXQ Drake Technical Net – Net Control for 11 February 2024 W9MXQ@... ? ?
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Jim Shorney
