"Normal" is the one shown in my photos. On Tue, 04 Feb 2025 01:31:29 +0000 "Steve Wedge, W1ES/4 via groups.io" <w1es@...> wrote: I¡¯d just like to put the thing back to original.
Even the Heil elements now have transformers.
Steve Wedge, W1ES
-- 73 -Jim NU0C
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Re: The mysteriously modified 7077 (and nothing else¡)
It was working fine until Sunday. Perhaps, I¡¯ll try resoldering all the bad-looking connections and/or testing the transformer. As bad as it looks, it was working.?
Most of the stuff I see on eBay looks like ¡°pig-in-a-poke¡±stuff. If I have to, I can install a Heil kit and know that I will have a good mic. But if I can regain the performance without spending another $70, I¡¯m good with that.?
Steve Wedge, W1ES
Time flies like an arrow. Fruit flies like a banana.
On Mon, Feb 3, 2025 at 20:16, Jim Shorney via groups.io < jimNU0C@...> wrote:
That seems likely to be the same cartridge shown in the photos I posted to the group photos section. And yes, as I mentioned previously, it is a cheap CB-era low impedance dynamic cartridge. Thus the need for the transformer to step up the voltage.
On Mon, 03 Feb 2025 21:09:56 +0000
"Steve Wedge, W1ES/4 via groups.io" <w1es@...> wrote:
> I have just about run to the end of my patience with apps and webpages that still think they¡¯re in 1993.
>
> I should be able to up load photos. I will try again.
>
> Steve Wedge, W1ES
>
--
73
-Jim
NU0C
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Re: The mysteriously modified 7077 (and nothing else¡)
Teve¡none of your images cam through! ? Joe ¨C W7RKN ? From: [email protected] [mailto:[email protected]] On Behalf Of Steve Wedge, W1ES/4 via groups.io
Subject: [DRAKE-RADIO] The mysteriously modified 7077 (and nothing else¡) ? Here are some pics of what I found inside.? I have doubts as to the originality of the element itself, as it measures 430 ohms, resistive.? First photo shows what the element looks like in its housing. This all came apart without any tools.?
This is what the element looks like.?
This is the kludge I found in the base.?
Time flies like an arrow. Fruit flies like a banana.
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Re: Drake TR7, TX issue any ideas?
This is shown on the schematic. It appears you may have an early board. The PIN diodes are different also. This pair of PINs are used to inject the calibrator signal. On Mon, 03 Feb 2025 10:57:20 -0800 "Michael Jensen via groups.io" <kavigal@...> wrote: On further inspection I found this:
Those 2 pin diodes connected to a cap? It looks like some modification, how ever I see no holes in the PCB where those 2 pin diodes would go otherwise.
Early version of this board and legit or? -- 73 -Jim NU0C
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I¡¯d just like to put the thing back to original.?
Even the Heil elements now have transformers.?
Steve Wedge, W1ES
Time flies like an arrow. Fruit flies like a banana.
On Mon, Feb 3, 2025 at 20:12, Jim Shorney via groups.io < jimNU0C@...> wrote:
That's what the transformer is for. Although I will say it again, it is not impedance matching. It is a voltage step-up. Impedance matching in microphone circuits is a myth. This is well documented on the internet. Impedance matching is only important when you are transferring power. In fact the pro audio world recommends that the load impedance be 10x the microphone impedance.
https://www.prosoundtraining.com/2010/11/03/microphone-mythbusters-vol-5-impedance-matching/
On Mon, 03 Feb 2025 16:47:04 +0000
"Steve Wedge, W1ES/4 via groups.io" <w1es@...> wrote:
> One thing of note that I will repeat here is that the element itself -- disconnected from the rest of the mic -- measures 430 ohms with my Fluke 77 in resistance mode. That seems odd if the thing is supposed to be high-impedance.
--
73
-Jim
NU0C
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I prefer the C in tight quarters on CW. You can get crystal filters down to 250 Hz stock and 125 Hz if you search. In pileups, these are the equal to newer rigs¡¯ receivers.?
For everyday, casual CW, the B sounds quite nice.?
Understand that the shape factors of the two rigs¡¯ filters are fairly different. Some prefer one over the other.?
The CW subbands aren¡¯t as crowded as they were 20 years ago, so take that into consideration.?
73,
Steve Wedge, W1ES
Time flies like an arrow. Fruit flies like a banana.
On Mon, Feb 3, 2025 at 15:17, Craig W8CS via groups.io < craig_severson@...> wrote:
Hi Scott, have you read the VE3EFJ "Drakemod" manifesto? If I recall Wayne's verbiage, it's something like this:
?
The R-4B is a terrific receiver out of the box and it does everything well, however you won't get the selectivity of an R-4C. The R-4C stock is a bit of a waste compared to its potential due to some questionable design choices. A properly (Sherwood) modified R-4C is transformed and is an exceptional receiver.?
?
Others will have a much more technical take than mine. The 4B is great out of the box; the 4C requires some work to realize exceptional potential.?
--
Craig/W8CS
Greenville, SC
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Re: Drake TR7, TX issue any ideas?
You may need to check your internal grounds, including all screws and any copper fingers attached to boards. As well, the board cage covers need to be attached with all screws, snug but not over tightened. But first add the ground strap to the high pass filter module as shown in the attached photo. This will help with stability. Also check the predriver gain adjustment pot. In a healthy TR7 with the ALC adjustment set for 150 Watts on 20 Meters you should get close to 100 Watts on 10 and 15. This is normal. The ALC and predriver gain adjustments work together and if mis-adjusted can cause issues. You may also want to test the PIN diodes. Procedures are posted on the internet and in this group. On Mon, 03 Feb 2025 08:53:27 -0800 "Michael Jensen via groups.io" <kavigal@...> wrote: Hardly been using it for TX until recently, then I notice that on 10 Meter output is close to 2.5 watts..
Okay, not much.. On 15 meters the current draw is close to 31 amps to produce 100watts! Quite a bit.
more reasonably 21-22 amps on other bands.
So went for an TX alignment, if I crank up the pre drive I can get it up to ~60 watts on 10 meter
obviously not a good scenario and the dr7 board definitely does not like it as the display starts to be all over the place during TX,
with pre drive fully cranked up 40 Meters the PA self oscillates, not good.
So my thoughts, something in the pre drive section or bandpass maybe?
Looking for any suggestions before going nuts down that route.
Thanks on advance!
Best Regards, Michael - oz8abr -- 73 -Jim NU0C
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Re: The mysteriously modified 7077 (and nothing else¡)
That seems likely to be the same cartridge shown in the photos I posted to the group photos section. And yes, as I mentioned previously, it is a cheap CB-era low impedance dynamic cartridge. Thus the need for the transformer to step up the voltage. On Mon, 03 Feb 2025 21:09:56 +0000 "Steve Wedge, W1ES/4 via groups.io" <w1es@...> wrote: I have just about run to the end of my patience with apps and webpages that still think they¡¯re in 1993.
I should be able to up load photos. I will try again.
Steve Wedge, W1ES
-- 73 -Jim NU0C
|
That's what the transformer is for. Although I will say it again, it is not impedance matching. It is a voltage step-up. Impedance matching in microphone circuits is a myth. This is well documented on the internet. Impedance matching is only important when you are transferring power. In fact the pro audio world recommends that the load impedance be 10x the microphone impedance. On Mon, 03 Feb 2025 16:47:04 +0000 "Steve Wedge, W1ES/4 via groups.io" <w1es@...> wrote: One thing of note that I will repeat here is that the element itself -- disconnected from the rest of the mic -- measures 430 ohms with my Fluke 77 in resistance mode. That seems odd if the thing is supposed to be high-impedance. -- 73 -Jim NU0C
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Re: R4B and T4XC Compatble?
Yes, you will need to adjust C61 on the R-4B, exactly the same as if you were using a T-4XB.?
You won¡¯t use the CAR OSC cable and should put a shorting plug in the T-4XC¡¯s PTO LAMP connector.?
73,
Steve Wedge, W1ES
Time flies like an arrow. Fruit flies like a banana.
On Mon, Feb 3, 2025 at 13:46, C Solomon < cdsol@...> wrote:
Will a R4B and a T4XC transceive?? Is there any difference in the interconnections from if I were using R4B with T4XB?
?
Thanks and '73
?
Carl - W5SU
Dallas TX
?
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Also attached as a .JPG file. ? Paul, W9AC ?
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From: [email protected] <[email protected]> On Behalf Of Paul Christensen via groups.io
Sent: Monday, February 3, 2025 7:07 PM
To: [email protected]
Subject: Re: [DRAKE-RADIO] 7077 Mic? Attached below is an LTSpice simulation of Astatic's T-UG8 2-transistor preamp.? Input Z varies between 100 Hz and 3 kHz.??As expected, the input Z varies based on differing hFE (beta) values.? The 2N2712 has a datasheet beta spec variance between 75 and 250.? The simulation uses a beta of 200.?
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Attached below is an LTSpice simulation of Astatic's T-UG8 2-transistor preamp.? Input Z varies between 100 Hz and 3 kHz.??As expected, the input Z varies based on differing hFE (beta) values.? The 2N2712 has a datasheet beta spec variance between 75 and 250.? The simulation uses a beta of 200.?
?
Paul, W9AC
?
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AC-4 Power Supply 10K Bias Trimmer Replacement
I purchased an AC-4 power supply and noticed one of the 3 lugs was snapped off.
Lots of 10Ks out there, but not with two mounting fins for the case.
?
Has anyone replaced these and found a suitable replacement?
?
Many thanks! 73.
--
Joe - W7BWA
Custer, WA
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Are you talking about a D-104 element? If so it should measure open circuit for DC. It should look like a capacitor. If you are getting resistance it is defective or else you are measuring something else.
Note that the bass roll off of the D-104 is not entirely due to its impedance. These were meant to be voice range mics with a fairly sharp peak at 3Khz and a roll off below about 1 Khz. The D-104 was the first crystal mic to be available commericially, c.1933. Initially there were two versions, the peaked voice version and a flat version. The flat version was not made for long but Astatic and others have made plenty of flat crystal mics. The load impedance affects mostly the bass roll off, not the HF peak. The peak is a result of mechanical and acoustic resonances built into the mic, it is a feature not a fault.
Unless there is something else in the mic a resistance in a crystal mic is an indication that the element is damaged.
The value Steve reports sounds like perhaps an electret whre an active element is being measured. It is the wrong value for a high impedance moving coil mic.
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On 2/3/2025 9:04 AM, Ralph Mowery via groups.io wrote: Attached is a file I have on the amplified d104
Ralph ku4pt
On Monday, February 3, 2025 at 11:47:14 AM EST, Steve Wedge, W1ES/4 via groups.io <w1es@...> wrote:
Folks, I will go down to the shack this afternoon and take photos.? I'll also draw, schematically, what it looks like (by hand -- I don't have any CAD by which to do this).
One thing of note that I will repeat here is that the element itself --
disconnected from the rest of the mic -- measures 430 ohms with my Fluke 77 in resistance mode.? That seems odd if the thing is supposed to be high-impedance.? I thus am led to believe that someone went into this mic and changed the element, adding all of the transformer/capacitor bits.
73,
Steve Wedge, W1ES
Time flies like an arrow.? Fruit flies like a banana.
Sent with Proton Mail <> secure email.
On Monday, February 3rd, 2025 at 10:50 AM, Bill Losef via groups.io <w.losefsky@...> wrote:
While we are on the subject of Mics, can someone share the wiring diagram for a powered D104 with me?
Bill N1WL
--
Richard Knoppow
Los Angeles
WB6KBL
SKCC 19998
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Re: The mysteriously modified 7077 (and nothing else¡)
I have just about run to the end of my patience with apps and webpages that still think they¡¯re in 1993.?
Steve Wedge, W1ES
Time flies like an arrow. Fruit flies like a banana.
On Mon, Feb 3, 2025 at 14:09, jerry-KF6VB < jerry@...> wrote: On 2025-02-03 11:06, Steve Wedge, W1ES/4 via groups.io wrote:
> Here are some pics of what I found inside.
Can't see the pix!
- Jerry, KF6VB
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My Semiconductor Inventory
As promised, this is my semiconductor inventory.? Some of the most common ones (ex.: 2N2222) I want to keep a minimum of 5 units.? There are others here that could come in handy in quite a few pieces of gear besides Drake.
If you see anything that you've been looking for, please email me OFF LIST to w1es@....
73,
Steve Wedge, W1ES
Time flies like an arrow.? Fruit flies like a banana.
Sent with secure email.
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Hi Scott, have you read the VE3EFJ "Drakemod" manifesto? If I recall Wayne's verbiage, it's something like this:
?
The R-4B is a terrific receiver out of the box and it does everything well, however you won't get the selectivity of an R-4C. The R-4C stock is a bit of a waste compared to its potential due to some questionable design choices. A properly (Sherwood) modified R-4C is transformed and is an exceptional receiver.?
?
Others will have a much more technical take than mine. The 4B is great out of the box; the 4C requires some work to realize exceptional potential.?
--
Craig/W8CS
Greenville, SC
|
? Scott
The R4C has sharper crystal filters but other than the standard filter for SSB you had to purchase the AM filter if you wanted 4KC or 6KC selectivity and you needed to purchase CW and RTTY filters. The R4C did not come with a noise blanker that was an optional purchase. In the AM mode the pass-band tuning on the R4C does not work only in SSB/CW.
Both are very good receivers the R4B and C with the C due to the crystal filters having a bit better overall selectivity in crowded band situations.
There are other differences in the tubes used and there were changes in the B and C receivers based on early to later models.
Hope this helps.
73 Tim
WB8UHZ
On Monday, February 3, 2025 at 02:14:06 PM EST, Scott N1IA via groups.io <soakland5@...> wrote:
Hello:
I have a question about the differences between the Drake R4B and R4C receivers. In some of the online chatter I have been reading, it is my understanding that the R4B is considered to be somewhat more desirable due to its passband capabilities.
I have a T-4XB (w/ digital display) and am weighing whether to pair it with a R4B instead of the R4C I have now. I haven't begun using it together yet as the R4C is currently being repaired.
My primary mode is CW.
Thanks
Scott N1IA
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Re: Drake TR7, TX issue any ideas?
All right I promise.. I'll stop spamming the group now :).
But one more thing that appears to be a modification, again any one got an idea of why and is it a known modification?
I'm referring to the 2 "extra" resistors.
?
?
Again Thanks! 73's Michael.
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Hello:
I have a question about the differences between the Drake R4B and R4C receivers. In some of the online chatter I have been reading, it is my understanding that the R4B is considered to be somewhat more desirable due to its passband capabilities.
I have a T-4XB (w/ digital display) and am weighing whether to pair it with a R4B instead of the R4C I have now. I haven't begun using it together yet as the R4C is currently being repaired.
My primary mode is CW.
Thanks
Scott N1IA
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Jim Shorney
Paul Christensen
Craig W8CS
Scott N1IA