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Re: 7077 Mic
Yes, I am quite aware of the D-104 head characteristics. I'm the guy who posts the attached graph whenever this comes up. For the TR7 470K x 2 is an ideal load for the cartridge with plenty of voltage
By Jim Shorney · #82487 ·
Re: 7077 Mic
I probably wouldn't have bothered with my TR7 - I would have just connected the D104 to that pin with the 470K resistor. This was in the mid-80's, and I wanted to hook it up to my TS-830S. I don't
By jerry-KF6VB · #82486 ·
Re: 7077 Mic
I have never run any electronics in a D-104/T-UGxx. Just a 470K or higher resistor in series with the audio line. Still plenty of output to drive most anything and the cartridge is happy with its
By Jim Shorney · #82485 ·
Re: 7077 Mic
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.
By Jim Shorney · #82484 ·
Re: 7077 Mic Correction
The 7077 is a dynamic mic, not a ceramic. I looked up 7075. Disregard my remarks. For more on the 7077 see: <https://www.wb4hfn.com/DRAKE/DrakeAcc/Drake%207077%20Microphone.pdf> -- Richard Knoppow Los
By Richard Knoppow · #82483 ·
Re: 7077 Mic
The 7075 is a ceramic element mic. Ceramic and crystal elements measure open circuit for DC. They look like capacitors. Your mic may be fine. -- Richard Knoppow Los Angeles WB6KBL SKCC 19998
By Richard Knoppow · #82482 ·
Re: 7077 Mic
I have a 7075; tried to get a resistance measurement that was not the PTT closure and every combination was open circuit. Don't have a schematic so I was fumbling in the dark. -- Craig/W8CS
By Craig W8CS · #82481 ·
Re: 7077 Mic
It sounds like someone may have added a filter to the mic. Can you tell if the transformer is open? Is is actually a choke?
By Richard Knoppow · #82480 ·
Re: 7077 Mic
That sounds like a legit mod. The D-104 element has very high output and does not need amplification for most rigs but can benefit from a very high load impedance. -- Richard Knoppow Los Angeles
By Richard Knoppow · #82479 ·
Re: 7077 Mic
This came with my first TR7, which I bought in 2019 from a ham. The mic worked fine until today. It¡¯s still a head-scratcher¡­ Steve Wedge, W1ES Time flies like an arrow. Fruit flies like a banana.
By Steve Wedge, W1ES/4 · #82478 ·
Re: 7077 Mic
I have a D-104 that I added circuitry to. A JFET source follower. No gain, but it presents an extremely high impedance to the mike element. Always gets me good reports. - Jerry, KF6VB
By jerry-KF6VB · #82477 ·
Re: 7077 Mic
I bought the Drake mic with bad mic element. Had an extra Kenwood MC-50 laying around and put that element inside and get great audio reports. Good luck and 73. Tony N5DIM
By Tony N5DIM · #82476 ·
Re: 7077 Mic
Sounds like something a CBer might do to get more audio grunt. - Jerry, KF6VB
By jerry-KF6VB · #82475 ·
Re: 7077 Mic
It is looking like I¡¯ll need to do that. The current element fits but there are series capacitors and that tiny transformer. These components seem to be good (capacitors are dead-on). I was shocked
By Steve Wedge, W1ES/4 · #82474 ·
Re: 7077 Mic
I put the Heil element in mine. Works great now. Larry - KB9VY Sent from [Proton Mail](https://proton.me/mail/home) for iOS
By KB9VY · #82473 ·
7077 Mic
Hi, gang! 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
By Steve Wedge, W1ES/4 · #82472 ·
DRAKE NET UPDATE ( February 2, 2025 )
We had 35 check-ins to our net today on 40 meters. More information on the net can be found at Ron's web site at www.wb4hfn.com . The radio's used on the net today were: 8 TWINS 2 TR3 9 TR4(x) 4 TR5 6
By M Gilger · #82471 ·
Re: Tr7 recommission
Thanks Jim Just need to see if I can get scope leads into the housing to check out the CAL pin diodes. Kind Regards Mike G3ZCC
By Mike Davidsohn G3ZCC · #82470 ·
Re: Drake T-4XB rubber feet
Hi Mike: Ok good point - good thing Heather didn't see my e-mail! She is sitting beside me as I type this! After 48-1/2 years that's not about to change on my watch. Let's put it this way...Drake rigs
By VE7PS · #82469 ·
Re: Drake T-4XB rubber feet
Peter, to clarify, Get married or selling the drakes? Mike, WB8VGE
By mike bryce · #82468 ·