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Re: One last call for Help..T-4XB
Tim, I was under the impression that Ron retired from Drake repair about a year ago. Can anyone confirm or deny that? 73, Mike KE5YTV
On Wednesday, January 31, 2024 at 03:08:24 PM CST, Tim Randa <randaranch@...> wrote:
One last request for ideas before shipping my T-4XB off to guru Ron Baker for his magic. I suddenly had what seems to be sidetone bleed through. When the radio is keyed in cw mode there is a constant fuzzy tone. When you press the cw key the actual sidetone is heard above the volume level of the bleed through but the background buzz/tone is always present. This does not happen in ssb mode. I had hoped replacing a possible gassy 6EV7 tube might fix it but no luck. Years ago I had installed the hayseed capacitor?can in a different set of B's but just can't remember if that was for this issue or not. The twins just aren't usable for me with this issue. ?
Any ideas you can send my way would be appreciated?greatly
?
73 de Tim? K?FL
Kansas
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One last call for Help..T-4XB
Tim Randa
One last request for ideas before shipping my T-4XB off to guru Ron Baker for his magic.
I suddenly had what seems to be sidetone bleed through. When the radio is keyed in cw mode there is a constant fuzzy tone. When you press the cw key the actual sidetone is heard above the volume level of the bleed through but the background buzz/tone is always present. This does not happen in ssb mode. I had hoped replacing a possible gassy 6EV7 tube might fix it but no luck. Years ago I had installed the hayseed capacitor?can in a different set of B's but just can't remember if that was for this issue or not. The twins just aren't usable for me with this issue. ?
Any ideas you can send my way would be appreciated?greatly
?
73 de Tim? K?FL
Kansas |
Re: RV75 Issues
On Mon, Jan 29, 2024 at 11:31 PM, Joe Pyles wrote:
even though the capacitance was in spec the ESR was way offIn quickly checking ESR today I noticed this in at least one instance. All new caps ordered per Jim's parts list. Jim: Thanks for making this so easy: go to Mouser website, enter PN's & quantity, checkout. In looking more carefully at the 10K resistor described by Peter (aka Steve) as "broken," that description appears to be accurate on close inspection. I see no evidence of burning on the resistror body or PC board. How this would come to be broken and positioned as I found it is not at all clear, except by human intervention. This resiistor does not appear on my manual ckt diagram. OTOH, the 150 ohm resistor shows very clear evidence of burning on both the resistor body and PC board. This resistor connects to the "Enable" line via the RV75 to TR7 cable and appears to bias the PIN diode on to enable RF output. A quick check of the PIN diode seems to indicate it is OK. I'll need to look at the TR7 ckts to better understand how this is supposed to work. I have spent considerable time visually inspecting both boards and see no obvious physical problems beyond the failed resistors. There is some evidence of rework around two DIP IC's on the digital board, but this may have been done by Drake on the production line. My current plan is to replace the defective resistors and any caps where the value or ESR is out of line. I'll also investigate the "Enable " line back into the TR7. Once this is done I dont see that I can go much farther without reassembling the RV75 and powering it up with the TR7. RB |
Re: RV75 Issues
I have 2 RV75 VFOs and on both of them I started hearing strange noises when tuning across a signal. This was very noticeable on AM. The internal PTO did not make the noises. I put a scope on the voltage rails and there was all kinds of noise on them. I started removing the electrolytics 1 at a time and even though the capacitance was in spec the ESR was way off. So I replaced all of the electrolytics and the noise on the DC voltage rail was gone and the noise when tuning across signal was gone. They both have been regular use for the last 5 years with no more problems.
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73, Joe Pyles KC9LAD At 10:53 PM 1/29/2024, you wrote:
There is a method to my madness. Sub standard or failing capacitors can cause all sorts of strange problems. The RV75 was released in 1982. That's over 40 years ago. |
Re: RV75 Issues
There is a method to my madness. Sub standard or failing capacitors can cause all sorts of strange problems. The RV75 was released in 1982. That's over 40 years ago.
73 -Jim NU0C On Mon, 29 Jan 2024 15:34:43 -0800 "Rick K8EZB" <frboswell@...> wrote: I'll get to this but first trying to do a top level assessment of what the problem might be. Since the caps seem OK for now, I'll look for other possible causes first. My approach is to attempt to get this gear limping along and then tidy up the seconday issues. So far I have only about an hour of time into this, and am seeing all this for the first time; still much to learn. Per your suggestions, going slow and taking plenty of pictures! -- 73 -Jim NU0C |
Re: RV75 Issues
On Mon, Jan 29, 2024 at 03:59 PM, John K5MO wrote:
"Fixing" too much stuff at once can inject additional problems into the mix ,often masking the initial problem !Been there, done that too! I wont plug in the soldering iron until I have a strong conviction as to what the problem is.? RB |
Re: RV75 Issues
RB That's a wise strategy.? "Fixing" too much stuff at once can inject additional problems into the mix ,often masking the initial problem ! I'm sensitive to this behavior as I've done it multiple times myself...? :-) John K5MO On Mon, Jan 29, 2024 at 6:34?PM Rick K8EZB <frboswell@...> wrote: Just replace them.I'll get to this but first trying to do a top level assessment of what the problem might be. Since the caps seem OK for now, I'll look for other possible causes first. My approach is to attempt to get this gear limping along and then tidy up the seconday issues. So far I have only about an hour of time into this, and am seeing all this for the first time; still much to learn. Per your suggestions, going slow and taking plenty of pictures! |
Re: R4B loose wire on board 8 (crystal calibrator)
Joe, ? |
Re: RV75 Issues
Just replace them.I'll get to this but first trying to do a top level assessment of what the problem might be. Since the caps seem OK for now, I'll look for other possible causes first. My approach is to attempt to get this gear limping along and then tidy up the seconday issues. So far I have only about an hour of time into this, and am seeing all this for the first time; still much to learn. Per your suggestions, going slow and taking plenty of pictures! Thanks for your response. RB |
R4B loose wire on board 8 (crystal calibrator)
Good day,
I have the R4B out of the cage getting ready to replace the electrolytic capacitors. I was looking around for anything out of place before I got started. Upon inspection, I saw a red wire that is soldered to the crystal calibrator board #8 that is not attached on the other end. I've attached two images. One is from my R4B, and the other is from the K4OAH CD. I don't see the same red wire on Garey's image, so I'm scratching my head a bit over here. The red wire in my image is soldered to the chasis grounded perimeter trace of the board that is connected to the ground screws.? Any thoughts on this? I'm attaching two images. One from Garey's CD, and the other is from my R4B. Thanks! Joe ki5o |
Re: Looking for a working Drake T4X
Not?sure this?got to you.?? I have a R4A and T4X combo.? All working as I have recently restored both.? I would be willing to sell both or either.? Assume that your power supply?is good?? Also have the?AC4 and MS4 if?you?wish.? If you are interested, I will send a pix of what you want. Also let me know about the broken switch.? I have a parts T4XB and it has a good switch.? It would be a real job to replace, but if it is just a wafer, it would be "easier." David Assaf III W5XU, VP8RXU ? On Sun, Jan 28, 2024 at 9:45?PM Kevin W2TVS via <johnlamondwyrk=[email protected]> wrote: Recently, I sent my Drake R4A and T4X to WB4HFN for a restoration and repair.? He was able to restore my R4A, but the T4X was deemed unrepairable due to the broken band switch, intermittent function switch and bad final tubes, ?I am now searching for a working Drake T4X at a reasonable price.? I have a working power supply, so I only need the transmitter itself.? If anyone has a working Drake T4X that they would be willing to sell, please contact me.? Thank you for reading this. ?73, Kevin W2TVS |
Re: Power Supply questions
Got it. Thanks¡ personal account sent directly from google mail. please pardon lack of outlook features... On Mon, Jan 29, 2024 at 4:46?PM VE7PS <ve7ps@...> wrote:
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Re: Power Supply questions
Joe: You'd have to jumper the switched line in the rig power plug as well (not the AC Line cord!).? You could do that internally in the PS. I've seen PS-7's with a rear SPDT switch added that would allow this to be easily done, and reversed as easily too. 73 Peter VE7PS On Mon, Jan 29, 2024 at 1:42?PM Joseph K4JNG <jgraif1@...> wrote:
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Re: Power Supply questions
Thanks, Peter but I¡¯m missing something here. I thought the power supply could only ¡°power up¡± if it is connected to a transceiver¡ BTW, already planning a remote switch for the PS7 to protect the TR7. personal account sent directly from google mail. please pardon lack of outlook features... On Mon, Jan 29, 2024 at 4:32?PM VE7PS <ve7ps@...> wrote:
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Re: Power Supply questions
Joe: You could use one of those cheap internet "wall wart" style switches that you just plug into the wall, then plug the PS-75 into the switch.? Install the program on your smart phone and you're done.? It?does mean you have to carry your phone with you to the shack. I am using one to provide the "delay" needed to start a Kenwood VFO-230 after the TS-830s is turned on.? It was intended to be a temporary measure until I could build a little delay relay circuit into the VFO-230, but works so well that?may never happen! 73 Peter VE7PS On Mon, Jan 29, 2024 at 12:26?PM Steve Wedge, W1ES/4 via <w1es=[email protected]> wrote:
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Re: Power Supply questions
Thanks, Jim. I see the plate. Couldn't I just mount my box fan on the top
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cover right where that plate is? It already has an AC power cord. joseph n. graif k4jng -----Original Message-----
From: [email protected] <[email protected]> On Behalf Of Jim Shorney Sent: Monday, January 29, 2024 3:30 PM To: [email protected] Subject: Re: [DRAKE-RADIO] Power Supply questions Joe, The PS7 has a spot on the rear panel for mounting a Drake FA7 or equivalent cooling fan. Look for the square plate right behind the main filter caps. There is a two pin AC socket next to is to power a 120VAC fan. And you do want to pull air out. 73 -Jim NU0C On Mon, 29 Jan 2024 10:14:30 -0800 "Joseph K4JNG" <jgraif1@...> wrote: I hope it's OK to combine these two questions into a single thread. First,now that I have acquired a PS7, I thought about using my PS75 to power my CW75 and SP75, but with no rig attached to it, how would I power it up? Second, I have a 4.5" X 4.5" box fan that I wish to use on the PS7. Looking at the top from the front (strap) side, which "quadrant" would be the best over which to situate the fan. Aslo, I assume the fan should be "sucking" air out as opposed to blowing it in.
-- 73 -Jim NU0C |
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