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Re: T4XC failure?
I don't understand this. Low resistance, ideally NO resistance, of the key contacts is their normal condition. What am I missing here?
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On 12/30/2024 12:19 PM, Jay W6CJ via groups.io wrote:
Gary & Group, A straight key with intermittently low-R contacts was the cause of this meltdown. --
Richard Knoppow Los Angeles WB6KBL SKCC 19998 |
Re: R-4A BFO Gremlins
Where can I find details of Sherwood's product detector fix for the 4B? I have one, which I need to work on for other reasons. If its not an extensive mod, and it really makes a difference, I would like to do it.
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On 12/30/2024 1:11 PM, Gary WB6OGD via groups.io wrote:
without the cap is from 1966. --
Richard Knoppow Los Angeles WB6KBL SKCC 19998 |
Re: TR-5 BPF AMP Board Oddness
Lyndon VE7TFX
Jim, you're looking at the wrong board. The picture you sent is
of the pre-mixer board. The board you want is accessed through the bottom of the chassis. Open the radio on its back, with the rear panel facing you. The BPF Amp board is on the left side, above the compartment where the output filters live. See the picture on page 5-9 of the manual. --lyndon |
Re: TR-5 BPF AMP Board Oddness
Lyndon my TR5 is serial 1159 and picture added.? 73, Jim VE1RB On Mon, Dec 30, 2024 at 4:20?PM Lyndon VE7TFX via <lyndon=[email protected]> wrote: Lyndon VE7TFX writes: |
Re: R-4A BFO Gremlins
Yeah, I think the cap is the correct fix.? But Steve, you did fix it, can't argue with success.
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Your receivers must have worked in the past, without cap nor resistor!? Aging must explain it.
This year it might take a 1K, next year a 2K?
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If you are lowering the supply voltage, you are probably also lowering the output amplitude too.
Might not be any problem but might lead to signal degradation?
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Interesting, you both seem to have 1967 radios, the "bad" schematic without the cap is from 1966.
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BTW, the real fix for the 11 tube R-4A and the R-4B is Rob Sherwood's product detector mod.
This makes a real difference, mostly in the Slow AVC.? Highly recommended, my R-4B has never
sounded better.
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73,
Gary
WB6OGD
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Re: TR-5 BPF AMP Board Oddness
Lyndon VE7TFX
Lyndon VE7TFX writes:
Anybody know what's going on here? I have another TR-5 (s/n 1024)I popped the other one open, and it has the expected board (see attached). So it would appear that something changed between #1024 and #1051. But in my rather limited searching I can't find any documentation related to this. If any of you have a TR-5 in the s/n range 1025-1050 and are inclined towards doing a bit of detective work, I'd appreciate it if you could pop off the bottom panel and let me know which version of the board you have. --lyndon |
Re: T4XC failure?
Gary & Group, RGR - the solder blob could have fallen from where the parasitic chokes connect to the top of the larger choke. Looks like I'll be buying parasitic chokes, Sylvania (?) finals and maybe a driver. A straight key with intermittently low-R contacts was the cause of this meltdown.?? I discovered this when I plugged the key into another transmitter - so check those contacts. 73 Jay On Mon, Dec 30, 2024 at 9:46?AM Gary Follett via <xntrick1948=comcast.net_at_groups.io_lastradioman@...> wrote:
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L4B replacement potentiometer
Fellow Drake Enthusiasts, Happy New Year to all!!! A while back somebody had mentioned that Mouser part number?313-1601F-100K was a direct replacement for the L4B pot, right resistance, with a push pull switch. ?However, that particular pot does not have a shaft that is long enough for the L4B. ?Might I have the part number wrong? I already have some pots that are direct replacements after I machine the mounting collar to the right length. ?However, if there are direct replacements it would save me some time. Can you help? 73, Evan, K9SQG |
Re: TR-4C problem on 40 meters FIXED
On 2024-12-30 07:42, Dieter Horst wrote:
But isn't it wonderful to be able to bring all these Drakes back to*** Or a FTDX10. Mine has a problem with the CAT control over USB. Unfixable. I did identify the chip responsible for that function, and replaced it. What a PITA. Still doesn't work. And there's no WAY to get that big card out and still have it function for troubleshooting. Yaesu doesn't fix them either. Just replace. $850 for the card, plus a couple hours of labor. - Jerry, KF6VB |
Re: R-4A BFO Gremlins
Welp, I guess I need to put my receiver back on the bench and take a butcher's... Steve Wedge, W1ES Time flies like an arrow.? Fruit flies like a banana.
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On Monday, December 30th, 2024 at 10:49 AM, Gary WB6OGD via groups.io <winbladgary@...> wrote:
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Re: R-4A BFO Gremlins
I'll have to go and look.? I can remember that it was built in 1967 because it has the QC tag with it.? Since I reported it to Ron, the s/n is between 6136 and 6968.? Mint condition.? I bought it from a friend who was collecting as much Drake stuff as he could but never got around to putting the station together.? He has a good eye and my A Line is a great proof of that. Steve Wedge, W1ES Time flies like an arrow.? Fruit flies like a banana.
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On Monday, December 30th, 2024 at 10:18 AM, Dave W7GZ via groups.io <w7gz@...> wrote:
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Re: Looking for advice on T4XB issues
Excellent.? Yes, I know that removing covers -- especially on the transmitters and transceivers can bump tubes and that can cause them to be intermittent or not work at all.? The transmitters and transceivers are move vulnerable because of tubes located very close to the back that are not protected.? The C versions have better protection but there are still one or two tubes that can get pushed over when you're rolling the rig around doing work on it. Glad to hear that you've got her going again.? I hope to try and do some SKN and would like to use my T-4X with my 1-A but not sure if I'll get those connections made up in time.? If not, either my A Line or my Collins S Line will be employed. 73, Steve Wedge, W1ES Time flies like an arrow.? Fruit flies like a banana.
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On Monday, December 30th, 2024 at 10:28 AM, Jason Hissong via groups.io <jhissong@...> wrote:
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Re: R-4A BFO Gremlins
Thanks, Gary, for the explanation. I replaced my 1K pull-down resistor with a 0.1uf and it seems to work fine. Obviously that point of the oscillator wants to be at RF ground. I feel much better about the capacitor solution than the 1K solution that matched my knob fiddling. I'll confirm it tonight when the radio is truly cold. The flux around the .47 is from my swapping it out to see if it was bad. Dave
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Re: T4XC failure?
¿ªÔÆÌåÓýAre you saying that the parasitic choke got hot enough to melt solder? Safe bet the tube(s) are bad.Gary W0DVN
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Re: TR7 next problem
¿ªÔÆÌåÓýThat is WAY too high!!The maximum that should be seen at this point is ~15 volts, the high end of 10 meters. 20 volts here would push the VCO to its maximum frequency, if it is running at all.? Is there any RF signal coming out of the VCO? You may have answered this previously but I seem to have forgotten the answer. If there IS RF, here, what is its frequency? Something is telling the PLL phase detector to put out a voltage thinking that the frequency is too low, which is why the voltage on RFC505 is so high. Can you short RFC505 cold end to ground? This SHOULD make the VCO, if it is operating, go to the low end of its range in frequency. This point is fed via a 100K resistor from U504B so this will not hurt anything. Gary W0DVN PS: Not taking into account C516 and C517, I had previously stated that voltage across the tuning diodes depended one the voltage at Q504 Drain. This was an error on my part. Those two capacitors isolate the DC on the tuning diodes from the Drain of the oscillator FET. Cn you short?
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Re: TR-7A No Output
On 2024-12-29 20:37, Jim Shorney via groups.io wrote:
The component leads are flat soldered to the top side. You do need to take care though that you do not rip theSpace permitting, I would access the top with a nice sharp pair of snips, and cut the leads of that regulator flush with its body. Then desolder each lead, one at a time. - Jerry, KF6VB |
Re: R-4A BFO Gremlins
> I have no idea what the added capacitor started the oscillator, but it has worked ever since.
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Drake had an error for a short while (like one month) and fixed the schematic with a missing capacitor.
From message #65666
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"C188 seems to be added to the same BFO circuit in the R-4B. It decouples the exact node you propose to put a 1K to ground!! Might be something Drake discovered in later models?? Also, schematic 919664054 seems to have a big error in the BFO, my downloaded from somewhere
copy has the correction marked in, that makes it like the R-4B schematic (the emitter connects to C163)." Steve somehow found that a resistor (to lower the supply voltage?) fixed the problem, but the real fix is
probably a capacitor like you and Drake used.
73,
Gary
WB6OGD
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Re: TR-4C problem on 40 meters FIXED
¿ªÔÆÌåÓýSorry Tom, I hijacked the thread! Of course, my problem did
affect all bands. Couldn't resist when I read about a solder joint problem. 73, Dieter DL5RDO
Am 30.12.2024 um 14:46 schrieb Tom
Smith:
Why would this only affect 40m? It would seem to me that a PTO problem would affect all bands. Thanks and happy new year to all! |
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