Re: Small lamp reference for Drake L7
Hello group. I need to replace the meter shunts for the Drake L7, LV and HV reading low. From the schematic Drake used 8 2.3 meg 1/2 watt resistors it appears from the schematic and manual pictures
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amfone
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#81580
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Re: T4X part id needed
Jim: Not sure which one is "blown". But all four ceramic feedthroughs shown in the pic are .001 uf/350V rated. *But*.....your HV line (+650VDC) is missing where the unused hole is. Is this what you
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VE7PS
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#81579
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T4X part id needed
Can anyone recommend a subsitute for a blown feed-thru cap that I need ? Appreciate any help Regards W6TTY
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Jim W6TTY
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#81578
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Re: TR7 next problem
yes it was a very pleasant surprised when I turned it on and it worked, The problem I have now id that when i SWITCH FROM lsb OR usB TO cw i get a signal in the receiver 5 over 9 and if I press the
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Jim Harris
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#81577
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Re: Small lamp reference for Drake L7
Thanks a lot for the reference, appreciated ! :)
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Mohamed VA2MKX
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#81576
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Re: R4C Sherwood audio mod questions
I stand corrected. Rob, NC0B Sent: Saturday, January 04, 2025 6:52 AM To: [email protected] Subject: Re: [DRAKE-RADIO] R4C Sherwood audio mod questions The computed -3 dB high-pass turnover
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Rob Sherwood
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#81575
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Re: R4C Sherwood audio mod questions
Hi Floyd, Thanks for pointing that out. I¡¯ll look at the board in my R-4C and see which is correct. It likely doesn¡¯t make much difference with the inverting input impedance. Rob, NC0B Sent:
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Rob Sherwood
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#81574
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Re: TR7 next problem
Well, there ya go! Nice catch. Doesn't it feel good? That is an interesting failure. Just a wild guess but I am thinking the lead had a weak spot, maybe a nick or a spot of corrosion, that caused it
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Jim Shorney
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#81573
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Re: R4C Sherwood audio mod questions
Thank you to all and to Rob especially. This is all very helpful - all gold. Nigel [email protected]> wrote:
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nigel patterson G3YDT
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#81572
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Re: T-4XC Sideband adjustments?
Tweak the cxr osc....such that the low end rolls off the same on LSB? as it does on USB.? ?That's as good as it will get.
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Jim VE7RF
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#81571
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Re: R4C Sherwood audio mod questions
The computed -3 dB high-pass turnover frequency is 123 Hz for 330 uF, and 204 Hz for 200 uF.? Pick either one based on personal roll-off preference. Paul, W9AC
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Paul Christensen
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#81570
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Re: R4C Sherwood audio mod questions
Rob - maybe it makes no difference at all, but there is a discrepancy in the component values for the AMP-4.? The text specifies the inverting input capacitor as 200 uF while the schematic shows it
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Floyd - K8AC
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#81569
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Re: TR7 next problem
I just wanted to let you know I managed to get the high VCO working. I was removing transistors and checking them on my tester, and when I removed Q504 and noticed that the Gate lead was broken off
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Jim Harris
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#81568
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Re: Speaker?
At a guess the smaller magnet was Alnico 5 or some other metallic magnet material while the larger one was ceramic. Ceramic magnets are very powerful but do not conduct magnetism well so tend to be
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Richard Knoppow
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#81567
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Re: TR7 Audio
40m cw at night in a big contest is a good time to rediscover the rf gain. :) John k5mo
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John K5MO
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#81566
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Re: Speaker?
It is not just hiss that is an issue. The wide range speaker will faithfully reproduce any out of band distortion products present in the audio. "Steve Wedge, W1ES/4 via groups.io"
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Jim Shorney
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#81565
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Re: VE3EFJ third mixer mod for the R4C
I did not roll of the high frequencies in the TDA2003 Audio Power Amplifier. The low-level audio stages were completely redesigned as the Drake system really sucked! Bob K9JU
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Bob Loving
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#81564
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Re: TR7 Audio
Well, it actually does make a signal more listenable by reducing the noise floor. "Steve Wedge, W1ES/4 via groups.io" <w1es@...> wrote:
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Jim Shorney
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#81563
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Re: T-4XC has a "condition"
Agree Gary....I have never set bias by turning "all controls to the left". Just make sure the GAIN pot at ZERO....CCW. Seems to have always worked in the past for me. Good hunch about possible 10m
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VE7PS
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#81562
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Re: Speaker?
Over the course of MS4 production, Drake used at least two different speaker driver variations. One has a large magnet, roughly the size of the SSN replacement being discussed. I've seen two minor
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Paul Christensen
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#81561
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