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Robyn T-240D Executive

It looks like Mike knows his way around this thing.



Towards the end of the video he is checking the radio out. When he puts it on ch20 you can hear someone in Alabama getting back to 21 Delaware. He (21) is one of our locals a few minuets north of me. LOL
 
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IF not a cap a tube, but it is (fortunately) a low-voltage system - so I hope it's a simple fix.

The nice thing about this chassis was the open yet compact design. Seems that tubes simplified the radio than like say a President Grant with all those discretes. A side benefit is that tubes - and more than likely yours may be, seem never to fail as original - never would fail due to even the filament warmer "standby" mode let the tubes thermionic emissions stay stable - like a dimmer switch - the filament can last nearly forever in this type of radio.

Just the caps may have failed and that may be a problem - unless the PLL in it is telling the unit to stay off - that is a loop issue and that is separate...
 
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I did some more digging and came to the conclusion that the mic cartridge on the D104 is bad. I swapped the head from my other mic and it works. The Galaxy mic I tried didn't work either because the Robyn is wired different. DOH! Anyway, can someone recommend a good replacement element? I have seen the W2ENY replacements on EBay.
https://www.ebay.com/itm/W2ENY-HiFi...712731?hash=item35d91b50db:g:~FYAAOSwu4BVtQm6
Does this turn it into something like a studio mic?
IMG_20180914_163513617.jpg
It is on a Tug8 stand.
 
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https://www.dxengineering.com/parts/hls-hc51retrokit

Another option Chris....
The kit you listed or this one above are not what I call Studio grade but give a nice natural sound audio...(which is what I like)...When someone says sounds just like you in-person...I stop messing with it!(y)
All the Best
Gary

PS: I have used the Heil kit...worked well for me on SSB and FM...little more price wise but wanted the "Heil Quality" in my element...and the damping foam insert was much more dense IMHO
Turned a $30 Hamfest purchase into a "Real" microphone:whistle::LOL:
https://static.dxengineering.com/global/images/instructions/hls-hc51retrokit.pdf
 
heilwire-300x102@2x.jpg
Another worth wild purchase also...used this or BELDEN version (actually I think Belden makes his) great stuff!!~!!...beat the dickens out of coil cord any day for bench usage.
https://heilsound.com/products/heilwire/
All the Best
Gary
 
Chris,
Take a look here.
https://www.adafruit.com/product/1713

Cheaper and may require a little more work to install (that's half the fun of this hobby :D) but it is also "customizable" as far as gain goes. Looks like a "set it and forget it" deal to me.

I also use the straight Belden mike cord. Love that stuff!

73's
David
 
Chris,
Take a look here.
https://www.adafruit.com/product/1713

Cheaper and may require a little more work to install (that's half the fun of this hobby :D) but it is also "customizable" as far as gain goes. Looks like a "set it and forget it" deal to me.

I also use the straight Belden mike cord. Love that stuff!

73's
David
Wow that's a neat little board. The automatic gain control would be a neat feature. I just don't know about the impedance matching needed and output level matching. Would be a neat project for sure. Unfortunately I don't have time to do something like this right now. I just want to get this one going so a drop in replacement is what I am going for right now.

 
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Have you got any Electret elements?

W2ENYKit.jpg

Because that is what this thing is. The "felt" suspends the element within the space the backing plate, and the windscreen use.

You may have some radios in you pile that use Electrets' these can work in that design - you now have a template...see above...

Go here for Astatic wiring guides...
http://www.cbtricks.com/mic_manuals/astatic/index.htm

You'll need 3 resistors and the schematic to the amp on the base of that TUG 8...

Take a trip to a "JoAnn" fabric or Similar (Michaels) store - they have that felt as padding - don't ask - but if you have the handset with the element - then you can use the handsets "insert" that the Element mounts in, and sits in the cradle that would otherwise use a dynamic element.

Fit the thickness of that element and cradle insert to suspend (you can see they hot glued) then re-wire the mike to handle that dropping resistor (ohmic value you'll need to make a divider for but usually 4.7K X 2 and tie them together as series - one side to the mics power switch, other to the battery negative) - the tied point routes up the unused 3rd wire leg of the pole in the stand - to power the element - the red wire goes to Mic "Hot" downlead and the shield to the black wire - the TUG8 wiring then uses the rest of it.

That yellow shrink wrapped dropping Resistor? Usually is 4.7K to as high as 6.8K - this will change "tone" so try using a 5K pot in series with a 2.2K resistor to "idealize" the level and tone of amplification...2.2K so not to overrun and burn out the element from the internal 9V battery...set you radio to PA to try out the effects to hear how it would work. Once level is set - lock n load...
 
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https://www.dxengineering.com/parts/hls-hc51retrokit

Another option Chris....
The kit you listed or this one above are not what I call Studio grade but give a nice natural sound audio...(which is what I like)...When someone says sounds just like you in-person...I stop messing with it!(y)
All the Best
Gary

PS: I have used the Heil kit...worked well for me on SSB and FM...little more price wise but wanted the "Heil Quality" in my element...and the damping foam insert was much more dense IMHO
Turned a $30 Hamfest purchase into a "Real" microphone:whistle::LOL:
https://static.dxengineering.com/global/images/instructions/hls-hc51retrokit.pdf
Thanks for the links, "just like you in person" is exactly what I am looking for.
 
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Have you got any Electret elements?

View attachment 25294

Because that is what this thing is. The "felt" suspends the element within the space the backing plate, and the windscreen use.

You may have some radios in you pile that use Electrets' these can work in that design - you now have a template...see above...

Go here for Astatic wiring guides...
http://www.cbtricks.com/mic_manuals/astatic/index.htm

You'll need 3 resistors and the schematic to the amp on the base of that TUG 8...

Take a trip to a "JoAnn" fabric or Similar (Michaels) store - they have that felt as padding - don't ask - but if you have the handset with the element - then you can use the handsets "insert" that the Element mounts in, and sits in the cradle that would otherwise use a dynamic element.

Fit the thickness of that element and cradle insert to suspend (you can see they hot glued) then re-wire the mike to handle that dropping resistor (ohmic value you'll need to make a divider for but usually 4.7K X 2 and tie them together as series - one side to the mics power switch, other to the battery negative) - the tied point routes up the unused 3rd wire leg of the pole in the stand - to power the element - the red wire goes to Mic "Hot" downlead and the shield to the black wire - the TUG8 wiring then uses the rest of it.

That yellow shrink wrapped dropping Resistor? Usually is 4.7K to as high as 6.8K - this will change "tone" so try using a 5K pot in series with a 2.2K resistor to "idealize" the level and tone of amplification...2.2K so not to overrun and burn out the element from the internal 9V battery...set you radio to PA to try out the effects to hear how it would work. Once level is set - lock n load...
Too late, I have already ordered the W2ENY kit. The dropping resistor changing the tone sounds interesting, I will have to play with that.
 
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Well you guys aren't going to believe it. I hope you don't get tired of messing around with me and my junk. The original D104 element works now. For some reason I was tempted to plug it in and now it works. I am not crazy. I did A/B tests swapping it with the one from my other mic and it really didn't work. I can hardly believe it myself. I guess its like any other device that is 40 years old, old machines and old cars. I have seemingly fixed machines at work just by walking up to them. Some people refer to this phenomenon as F.M. (F*****G Magic)
 
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Oddly enough, when we started doing autopsies on dead MC-320 cartridges the piezo element is almost always still strong.

What goes bad is the glue that holds the element's tiny rubber support blocks to the plastic cup. The element just wiggles around in the wind. With no attachment to the floor of the cup, the element can't flex against the up-and-down motion of the diaphragm and produce voltage.

Still need to find out where to buy the same gauge and alloy aluminum foil. Might be worth having a mold made to shape new diaphragms and rebuild them.

The original diaphragm will never come loose without damaging it.

73
 
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