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
|
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
|
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.
|
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
|
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.
|
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
|
Re: The mysteriously modified 7077 (and nothing else¡)
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
|
Re: Drake Collection For Sale
Contact Ken at ken19604520 at sbcglobal.net
|
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.?
Steve Wedge, W1ES
Time flies like an arrow. Fruit flies like a banana.
|
Drake Collection For Sale
I am posting for a local ham, K6SAD, I recently purchased a TR-4CW and C line from.
He has a good size collection he is trying to sell.
Pictures available on request.
Please contact Ken directly at ken19604520@... if interested.
He prefers local pickup north of Sacramento as shipping is a challenge.
73,
Steve
W1SRD
?
====================================================
DRAKE TR7, PS7, MS7 ---- $600.00
DRAKE C TWINS WITH AC4 AND MS4 ----- $600.00
DRAKE B TWINS WITH AC4 AND MS4 ----- $500.00
DRAKE B TWINS $450.00
DRAKE WH7 ---- $125.00
DRAKE RV7 ---- $150.00
DRAKE P75 ---- $50.00
DRAKE C4 COMPLETE ---- $400.00
DRAKE C4 COMPLETE ---- $400.00
DRAKE 2B ---- $150.00
DRAKE 2BQ ---- $125.00
DRAKE RV4C ---- $100.00
?
6JB6A TUBES (HAVE LOTS OF THEM) ---- $30.00 EACH (6 or more $25 each)
?
EV 664 WITH HEAVY BASE ---- $95.00 EACH
SHURE 444 ---- $65.00
SHURE 444D ---- $85.00
==================================================
?
?
?
?
|
Welp, this thread has been taken over, so I¡¯ll post a new one.?
Steve Wedge, W1ES
Time flies like an arrow. Fruit flies like a banana.
On Mon, Feb 3, 2025 at 12:40, Lorne VE6CSR via groups.io < lorneinthesand@...> wrote:
Is it going to need anything special to hook it up to a Drake 4 line T-4XC. Without the nine volt battery.?
On 2025-02-03 09:16, Lorne VE6CSR? via groups.io wrote:
> From the inside bottom of a Silver Eagle
> VE7LXX
>
Interesting.? Looks like that amp has an input impedance of about 1
megohm,
which is set by the base biasing resistor.
????????????????? - Jerry, KF6VB
|
Re: Drake TR7, TX issue any ideas?
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?
?
Best 73's Michael.
|
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
?
|
Is it going to need anything special to hook it up to a Drake 4 line T-4XC. Without the nine volt battery.?
toggle quoted message
Show quoted text
On 2025-02-03 09:16, Lorne VE6CSR? via groups.io wrote:
> From the inside bottom of a Silver Eagle
> VE7LXX
>
Interesting.? Looks like that amp has an input impedance of about 1
megohm,
which is set by the base biasing resistor.
????????????????? - Jerry, KF6VB
|
On 2025-02-03 09:16, Lorne VE6CSR via groups.io wrote: From the inside bottom of a Silver Eagle
VE7LXX
Interesting. Looks like that amp has an input impedance of about 1 megohm, which is set by the base biasing resistor. - Jerry, KF6VB
|
From the inside bottom of a Silver Eagle?
VE7LXX
toggle quoted message
Show quoted text
While we are on the subject of Mics, can someone share the wiring diagram for a powered D104 with me?
On Monday, February 3, 2025 at 09:45:39 AM EST, Steve Wedge, W1ES/4 via groups.io <w1es@...> wrote:
This one has no foam but there¡¯s a white cottony-looking material that is right behind the grille. It looks identical to the Astatic 1011 I have. That mic does have a powered amp, which I run pretty low with my 4 Line sets. It also has a tone control,
which I run fully-up so I don¡¯t get muddy audio.?
The 1011 was made to have an amp in it ¡ª the two sliders in the base attest to that.?
The 7077 has never been powered. The work done inside the 7077 was obviously done after manufacture. The workmanship is terrible and everything is black electrical taped together.?
Steve Wedge, W1ES
Time flies like an arrow. Fruit flies like a banana.
On Sun, Feb 2, 2025 at 19:27, Jim Shorney via groups.io < jimNU0C@...> wrote:
You can find photos of the inside of a 7077 here:
/g/DRAKE-RADIO/album?id=252836
It does have a small transformer in it to step up the voltage output to drive a TR7. No capacitors. And a cheap CB-era dynamic cartridge hidden inside the head. After this many years the blast foam behind the grill will have decayed to crunchy dust. Both the
cartridge and the blast foal are easily replaceable.
On Sun, 02 Feb 2025 23:11:59 +0000
"Steve Wedge, W1ES/4 via groups.io" <w1es@...> wrote:
> I went on to the 7238 Drake Pre-net this afternoon and strange things were happening. I heard some noise in the speaker when the PTT was pressed and WB0IQK said that I sounded excessively tinny. I was fortunate to have my $10 GE-branded Shure 444, which worked
like a charm but, of course, I want to know what is wrong with the 7077, so I took it apart.
>
> Oy, vey! What a mess inside! Someone had put in a couple of capacitors (low value) and what looks like a transformer. It's all kludged in there, so I know this ain't no factory job! Lots of lousy workmanship and electrical tape trying to hold things together!
>
> The mic element I can't be sure if it's correct, though it looks like it all fits together like it should. The mic element measures around 430 ohms on my Fluke 77.
>
> Is this simply a case of the wrong element in this mic? The TR7 manual specifies a high Z mic. I am tempted to simply get a Heil element for high Z and being done with it.
>
> If any of you have a 7077 mic, can you measure resistance across the mic element for me? This should be from ground to pin 1 of the mic plug.
>
> TNX & 73,
>
> Steve Wedge, W1ES
--
73
-Jim
NU0C
|
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 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?
?
|
Drake TR7, TX issue any ideas?
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
|
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 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?
On Monday, February 3, 2025 at 09:45:39 AM EST, Steve Wedge, W1ES/4 via groups.io <w1es@...> wrote:
This one has no foam but there¡¯s a white cottony-looking material that is right behind the grille. It looks identical to the Astatic 1011 I have. That mic does have a powered amp, which I run pretty low with my 4 Line sets. It also has a tone control, which I run fully-up so I don¡¯t get muddy audio.?
The 1011 was made to have an amp in it ¡ª the two sliders in the base attest to that.?
The 7077 has never been powered. The work done inside the 7077 was obviously done after manufacture. The workmanship is terrible and everything is black electrical taped together.?
Steve Wedge, W1ES
Time flies like an arrow. Fruit flies like a banana.
On Sun, Feb 2, 2025 at 19:27, Jim Shorney via groups.io < jimNU0C@...> wrote:
You can find photos of the inside of a 7077 here:
/g/DRAKE-RADIO/album?id=252836
It does have a small transformer in it to step up the voltage output to drive a TR7. No capacitors. And a cheap CB-era dynamic cartridge hidden inside the head. After this many years the blast foam behind the grill will have decayed to crunchy dust. Both the cartridge and the blast foal are easily replaceable.
On Sun, 02 Feb 2025 23:11:59 +0000
"Steve Wedge, W1ES/4 via groups.io" <w1es@...> wrote:
> I went on to the 7238 Drake Pre-net this afternoon and strange things were happening. I heard some noise in the speaker when the PTT was pressed and WB0IQK said that I sounded excessively tinny. I was fortunate to have my $10 GE-branded Shure 444, which worked like a charm but, of course, I want to know what is wrong with the 7077, so I took it apart.
>
> Oy, vey! What a mess inside! Someone had put in a couple of capacitors (low value) and what looks like a transformer. It's all kludged in there, so I know this ain't no factory job! Lots of lousy workmanship and electrical tape trying to hold things together!
>
> The mic element I can't be sure if it's correct, though it looks like it all fits together like it should. The mic element measures around 430 ohms on my Fluke 77.
>
> Is this simply a case of the wrong element in this mic? The TR7 manual specifies a high Z mic. I am tempted to simply get a Heil element for high Z and being done with it.
>
> If any of you have a 7077 mic, can you measure resistance across the mic element for me? This should be from ground to pin 1 of the mic plug.
>
> TNX & 73,
>
> Steve Wedge, W1ES
--
73
-Jim
NU0C
|
Craig W8CS
Scott N1IA
