Re: R4B 50 Khz I.F. sweep.
50 KHz is hard. Most analyzers that could fall into ham hands don't go down that far. I have an old HP that goes down to 20 Hz but it would anchor a decent size boat. 73 -Jim NU0C On Sun, 19 Mar 2023 17:17:32 -0700 "W6MQI via groups.io" <w6mqi@...> wrote: Has anyone ever tried to sweep the 50Khz I.F. in the R4B with a spectrum analyzer?? WA8SAJ had a powerpoint presentation a few years ago showing screenshots using his SA to sweep the 50 Khz I.F., but he gave no real explanation of how he performed the test and adjustments for the passband curves. I have tried to reproduce his SA sweeps without success just can't seem to find the right input for the tracking generator and output from the R4B to the SA? input.? Anyone have success performing this procedure?
Dave
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Re: R4B 50 Khz I.F. sweep.
Guess I should mention I have the exact same spectrum analyzer as WA8SAJ used in his test.
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Has anyone ever tried to sweep the 50Khz I.F. in the R4B with a spectrum analyzer?? WA8SAJ had a powerpoint presentation a few years ago showing screenshots using his SA to sweep the 50 Khz I.F., but he gave no real explanation of how he performed the test and adjustments for the passband curves. I have tried to reproduce his SA sweeps without success just can't seem to find the right input for the tracking generator and output from the R4B to the SA? input.? Anyone have success performing this procedure?
Dave
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I think this is an example of the "real hams" make their own cables claim many like to make, he's just making an allowance for the elderly and handicapped... Ken, N2VIP
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On Mar 19, 2023, at 17:36, Jim W7RY via groups.io <jimw7ry@...> wrote:
?
At what age does elderly start??
Are you sure they wont sell them to the young or non handicapped?
Just askin...
Jim W7RY
On 3/19/2023 5:26 PM, Gregory Beat via
groups.io wrote:
Elderly or handicapped radio amateur can buy pre-made cables for
Drake?4-line Twins or Collins S-line?
from Joel at RF Connection (Gaithersburg,
MD)
RG-58 or RG-62 coax cable (you request).
<424FE80E-0C4C-4199-BD55-78BA72409F81.jpeg>
--
Thanks and 73, Jim W7RY
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At what age does elderly start??
Are you sure they wont sell them to the young or non handicapped?
Just askin...
Jim W7RY
On 3/19/2023 5:26 PM, Gregory Beat via
groups.io wrote:
Elderly or handicapped radio amateur can buy pre-made cables for
Drake?4-line Twins or Collins S-line?
from Joel at RF Connection (Gaithersburg,
MD)
RG-58 or RG-62 coax cable (you request).
--
Thanks and 73, Jim W7RY
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Elderly or handicapped radio amateur can buy pre-made cables for Drake?4-line Twins or Collins S-line? from Joel at RF Connection ( Gaithersburg, MD)RG-58 or RG-62 coax cable (you request). 
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DRAKE TECHNICAL NET UPDATE ( March 19, 2023 )
Today we had 31 stations checking into the net on 7.238. It was a bit rough with the Virginia QSO part?going on, but we made it through with little difficulty.?
The following radio's were used to check in.?
Twins = 10 TR4(x) = 5 TR5 = 1 TR7(x) = 5
73's, Mark, WB0IQK
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Re: Success- the vernier drive on my T-4XC is back together and working.
I tend to leave the drive alone unless there¡¯s a problem with moving the slug rack. The problem usually manifests itself at the high frequency end (10m). If resetting the preload won¡¯t fix it, then I¡¯ll take it out, clean it, inspect it and try to reposition the shaft as needed after putting in new grease.?
Even when I wash the chassis, I won¡¯t take apart a working drive. I keep the detergent away from the drive.?
73,
Steve Wedge, W1ES/4
Time flies like an arrow. Fruit flies like a banana.
Sent from Proton Mail for iOS
On Fri, Mar 17, 2023 at 21:36, Bill Leonard N0CU < billincolo73@...> wrote: After trying unsuccessfully for several days to reassemble the vernier drive on my T-4XC, I noticed a small ball bearing on the carpet under my work bench. Since the vernier drive is the only thing I had been working on that had any bearings, I assumed that it must have fallen out of the drive while I was removing it from the T-4XC. It turns out that this bearing is used as a spacer inside the large shaft. After placing it next to the spring inside the large shaft, I was able to reassemble the drive with just a slight amount of preload. The preload required is only that required to get the set screws on the large shaft to fit into the notch on the main shaft. The main shaft is the one that moves the coil slugs. The preload needed can easily be generated by a medium size screwdriver and no special clamp is required. Although removing the vernier allowed me to remove all of the old grease, I am not sure the improvement over what was achieved by simply cleaning the drive in place justifies the extra work involved in reassembling the drive.
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Bill N0CU
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Success- the vernier drive on my T-4XC is back together and working.
After trying unsuccessfully for several days to reassemble the vernier drive on my T-4XC, I noticed a small ball bearing on the carpet under my work bench. Since the vernier drive is the only thing I had been working on that had any bearings, I assumed that it must have fallen out of the drive while I was removing it from the T-4XC. It turns out that this bearing is used as a spacer inside the large shaft. After placing it next to the spring inside the large shaft, I was able to reassemble the drive with just a slight amount of preload. The preload required is only that required to get the set screws on the large shaft to fit into the notch on the main shaft. The main shaft is the one that moves the coil slugs. The preload needed can easily be generated by a medium size screwdriver and no special clamp is required. Although removing the vernier allowed me to remove all of the old grease, I am not sure the improvement over what was achieved by simply cleaning the drive in place justifies the extra work involved in reassembling the drive.
-- Bill N0CU
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For what it's worth, Drake does call it AGC on the schematic.? His statement as I read it is saying that as shipped with the 1 Meg AGC does not work properly and adding the 15K makes it work, At least that's the way I read it. It is also stated this was fixed in later T4's.
I saw this statement in another search -
The 15k AGC resistor is wired across the 1meg AGC resistor that was installed by the factory.? At least that is what Drake did in my T4X.? The 1meg was a design mistake by Drake that was fixed in later models.? A quick solution to the problem was to simply wire a 15k across the 1meg and settle for slightly less than 15k.? With a 1meg resistor there was no AGC.
Regards,
Frank Kamp, K5DKZ,? July 14, 2002
I wonder if K5DKZ is a member of this group? Perhaps he can explain it.
?
Doug, WA3DSP
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I have read that years ago, noted it on my schematic.
I do find it hard to believe a Drake factory screw up that makes it to not work!
I do have my T-4X on the bench right now, I will try to check it out.
I remember back in the day guys were bending a tube pin out to disconnect all ALC..? made for a bigger signal but with splatter.
They were hams but thought like CBer's.? Lowering that resistor might do pretty much the same.
Yes, AGC is ALC..? I am pretty sure Drake called it ALC, he is the only one calling it AGC, though it is the same.
Gain vs. Level.. pretty much the same to me, hi hi.
73,
Gary
WB6OGD
?
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In this article on conversion to 6146's? -? He states the following. This seems like a radical change of value. Is this valid? Exactly what does AGC do? Is this really better termed ALC?
Connect a 15k ohm, half watt resistor from the plate of V1B (AGC amp) to ground. This may only be needed on the T4X to correct a factory screw-up. The original value of the resistor here was 1 meg which would ensure that there was no AGC action. No one really noticed so it may not be a big deal. If you want the AGC to work on an old T4X, install the 15k resistor. No need to remove the original 1 meg resistor, just wire the 15k across it.
Doug, WA3DSP
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Re: TR7 Service Kit - Extender Boards Needed
Yes, finding .156 connectors is easy, perhaps I should've asked ones that are compatible with the originals as far as pin dia is concerned along with the hooks that hook over the edge of the pcb so the connector is not distorted when plugged in and unplugged.... Thanks for your help.
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Re: TR7 Service Kit - Extender Boards Needed
Mark,
No, tell ron to keep the listing for me.
Mike, WB8VGE
SunLight Energy Systems
The Heathkit Shop
.com/
J e e p
o|||||||o?
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On Mar 16, 2023, at 7:45 PM, Mark - WB0IQK < mgilger@...> wrote:
I'll let Ron know to remove Bob's ad for those boards. He might have forgotten to advise him that they were all sold.?
Mike, should I remove your boards from the parts & service doc on his site??
73's,
Mark
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BTW a 12GN7 while not a direct substitute has the same pinout and is about twice the plate dissipation and higher transconductance than the 12BY7. I could not find one to try but it would be an interesting to try if you could find one. It would definitely require retuning.
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Doug, WA3DSP
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I think I have answered my own question. These tubes are basically one and the same. I found quite a few in my stash, and this RCA is numbered with all three types. I ended up using a JAN GE 12BY7A which worked fine.
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Doug, WA3DSP
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Re: TR7 Service Kit - Extender Boards Needed
I'll let Ron know to remove Bob's ad for those boards. He might have forgotten to advise him that they were all sold.?
Mike, should I remove your boards from the parts & service doc on his site??
73's,
Mark
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Looking for a Excellent top cabinet if anyone knows where I might find one.
An excellent original R7A manual would be nice too.
Marty
KL7AM
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Re: TR7 Service Kit - Extender Boards Needed
Mike, FYI in Drake parlance this is known as the "Jumper Board" and is described as such in the TR7 service manual. 73 -Jim NU0C On Thu, 16 Mar 2023 11:07:38 -0400 "Mike Bryce" <prosolar@...> wrote: I did make a ¡®bridge¡¯ board to connect the cards necessary to run the transceiver without the DR board.
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Re: Sourcing T4Xany cathode and screen grid resistors
I don¡¯t have the answer to that. I did, however, throw out some carbon resistors recently (and I¡¯m in an ongoing process with my stock, which dates back decades) that were grossly out of spec, even for 10 or 20% parts. Those were probably from the 1930s, judging by their appearance.?
My stock came back to me from my friend Brent, W1IA (SK), who had received them from me in 2006, when I moved. I got them from a co-worker in the 1980s, and they belonged to his dad, who was a TV repairman, so most of the parts are at least 37 years old. Other parts had been added over the years by Brent and me.?
Most of the parts look more ¡°modern¡± and most of those are still good, so far.?
Not all of the resistors in our Drakes have gone out of tolerance. The parts are affected by time, use, storage environment and other factors.?
I tend to only start measuring components when something is not working right or if I need to adjust a pot or cap to its extreme value. One could go crazy worrying about the parts, so we have to invest a certain amount of ¡°faith¡± that the parts inside are ¡°close enough¡±.?
73,
Steve Wedge, W1ES/4
Time flies like an arrow. Fruit flies like a banana.
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On Thu, Mar 16, 2023 at 12:26, Bill Leonard N0CU < billincolo73@...> wrote: Steve, I agree. This is more of a temporary fix for me. Once I get everything working I will go back and replace them with new parts. What I don't remember is what is the drift profile of carbon comp resistors. Does continue indefinitely at a fairly constant rate or does it level off. If it is the latter, then I am not sure whether replacing them is necessary.
On Thu, Mar 16, 2023 at 9:56?AM Steve Wedge, W1ES/4 via <w1es= [email protected]> wrote: The problem with that with respect to the cathode and screen resistors is that the out of tolerance parts will continue to drift out of tolerance. It¡¯s best to use new replacements of the original value.
73,
Steve Wedge, W1ES/4
Time flies like an arrow. Fruit flies like a banana.
Sent from Proton Mail for iOS
On Thu, Mar 16, 2023 at 11:09 AM, Bill Leonard N0CU < billincolo73@...> wrote: Since I have several boxes full of resistors, I have simply been measuring the starting resistance and calculating what parallel resistance is needed. I trimmed the meter shunt to 1% and matched the cathode and grid resistor to 1-2%.
On Wed, Mar 15, 2023 at 8:58?PM Doug Crompton WA3DSP < wa3dsp@...> wrote: There is NO reason these resistors need to be 1%. 5 or even 10% are fine and you can always select from a stash to match them if that is your thing. They don't even need to be exactly the specified resistance, as long as it is close and they are reasonably matched. Someone put 10 ohm 2W cathode resistors in my T4XC. That vaue would probably be more likely to be found. The only resistor that might benefit from being 1% is the 3.3 ohm meter shunt, but that is also a stretch given the accuracy of the meter itself.
--
Doug, WA3DSP
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Jim Shorney
W6MQI
Greg W9GB
Doug Crompton WA3DSP
Gary WB6OGD
