<This is a common problem of rough handling.? That is why it was ALWAYS said to never lay the Eimac tubes on the side, always standing up and to treat them like fine crystal.

<Vince N8MQV

Tell that to UPS, Fedex,? USPS? etc.?

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If you plan on doing CW you may want to also take a look at the article here by Floyd K8AC:



73

-Jim
NU0C

On Sun, 11 Feb 2024 11:22:56 -0800
"Bill NZ0T" <nz0tham@...> wrote:

After fining the much better PDF copy of the sevice manual in the files here I have a plan to try tomorrow.

1.? Very low sidetone volume:? Check R1152 a 330 ohm on the IF/audio board to see if it's shorted, way out of tolerance or has been replaced with a different vvalue to lower the volume.? Maybe a PO wanted to use his keyer sidetone instead of the rig and with no sidetone adjutment in the rig that is how the PO soved it.
2.? Perform the null adjustment of C1901 on the rear LP assembly before I try adjusting the forward and reflected pots.? Maybe thats way out of adjustement and causing the other adjustments to not work which is affecting the ALC adjustment?? Worth a try.

I'll report back tomorrow.? But now it's time to cheer on my Chiefs!

73, Bill NZ0T

Mark,

On Sun, 11 Feb 2024 11:02:15 -0800
"atlasstuff" <g4fph@...> wrote:

@Mike: Thanks for you post. I hope you are in good health. I will send you an e-mail regarding the power supply board. TI and others have some amazing switching regulator IC's available these days. If I had time for a design challenge, it would be to have a go at replacing all of the linear regulators with them. The +24 and -5 Volt rails must run hardly any current. Has anyone measured the current draw on the +10 and +5 Volt rails. In any case, must be less than 5-Amp and 1-Amp respectively.

The +24 supplies a boost voltage to the PLL for faster lock. The -5 back-biases the PIN diodes on the IF filter board and typically measures arounf -3 to -4. Not very critical it seems. I wouldn't go nuts about replacing the regulators. The original design is very good. There was a blurb in QST years ago about adding some bypass caps to the regulators to reduce noise. It may be in the group file section but if not I can probably dig it up.

@Group: I now have the TR-7 transmitter working OK. The Drake 7077 mic that came with the radio sounded somewhat average, so I plugged in the Shure 444 that I use on my other TR-7. It didn't work - what!? The reason was that this low s/n TR-7 did not have the 470k resistor installed between pins 1 & 4 on the rear of the microphone socket. It now has, and the 444 sounds good.

I was going to mention that eventually. I have a 7077. Not impressed with it. Most any other mic sounds better in my experience.

The transmitter produces 100 W RF out up to and including 20 metres. On 15 metres, it's down to around 85 W. On 10 metres, it's down to about 25 W, so some work to do. Despite having a low s/n of just over 1000, this TR-7 has the MkII pre-driver board in the PA, whic I guess is a good thing.

The ALC threshold is lowered by a pair of resistors on the band switch for 15 and 10 meters due to lower gain of the transistors at higher frequencies. A good PA deck should easily do 140+ on 20m and very close to 100 0n 15/10 when adjusted to service manual spec. The version 2 predriver was a standard upgrade by Drake service. Apparently they had a lot of trouble with the original.

I have some 'talkback' / low-level undemodulated SSB getting back into the speaker when I transmit. Think I read somewhere that the early models were prone to this and that separating out the Hi- and Lo- Amps lines in the DC power lead (like Atlas did!) helps. I will try this. Any other tips for getting rid?

That somewhere is probably here:



Also check that you have a 470uF capacitor on the bottom side from pin 10 of the Power Supply board to chassis.

I did have a nice find when I went digging to do the transmit carrier balance - an AUX 7 card installed, with the three Drake diode modules fitted for full 0 - 1.5 MHz receive coverage, plus a previous owner had made some, Christmas-tree style, modules for 30, 17 and 12 metres. So, I did have a bit of luck after all the pain!

Lucky score!


--

73

-Jim
NU0C

After fining the much better PDF copy of the sevice manual in the files here I have a plan to try tomorrow.

1.? Very low sidetone volume:? Check R1152 a 330 ohm on the IF/audio board to see if it's shorted, way out of tolerance or has been replaced with a different vvalue to lower the volume.? Maybe a PO wanted to use his keyer sidetone instead of the rig and with no sidetone adjutment in the rig that is how the PO soved it.
2.? Perform the null adjustment of C1901 on the rear LP assembly before I try adjusting the forward and reflected pots.? Maybe thats way out of adjustement and causing the other adjustments to not work which is affecting the ALC adjustment?? Worth a try.

I'll report back tomorrow.? But now it's time to cheer on my Chiefs!

73, Bill NZ0T

@Tom: Thanks for those fixes. I will remember to go grab the updated version. Coming to the radio with zero practical experience of what was inside, just finding where to put the probe was a real challenge until I found your document.

@Mike: Thanks for you post. I hope you are in good health. I will send you an e-mail regarding the power supply board. TI and others have some amazing switching regulator IC's available these days. If I had time for a design challenge, it would be to have a go at replacing all of the linear regulators with them. The +24 and -5 Volt rails must run hardly any current. Has anyone measured the current draw on the +10 and +5 Volt rails. In any case, must be less than 5-Amp and 1-Amp respectively.


@Group: I now have the TR-7 transmitter working OK. The Drake 7077 mic that came with the radio sounded somewhat average, so I plugged in the Shure 444 that I use on my other TR-7. It didn't work - what!? The reason was that this low s/n TR-7 did not have the 470k resistor installed between pins 1 & 4 on the rear of the microphone socket. It now has, and the 444 sounds good.

The transmitter produces 100 W RF out up to and including 20 metres. On 15 metres, it's down to around 85 W. On 10 metres, it's down to about 25 W, so some work to do. Despite having a low s/n of just over 1000, this TR-7 has the MkII pre-driver board in the PA, whic I guess is a good thing.

I have some 'talkback' / low-level undemodulated SSB getting back into the speaker when I transmit. Think I read somewhere that the early models were prone to this and that separating out the Hi- and Lo- Amps lines in the DC power lead (like Atlas did!) helps. I will try this. Any other tips for getting rid?

I got to try out my jumper board, when I went to balance out the carrier. Would have been nice if Drake had put a suitable hole in the DR-7 board so the pot on the transmit exciter that needs adjusting was easily accessible <grumpy face>. I did have a nice find when I went digging to do the transmit carrier balance - an AUX 7 card installed, with the three Drake diode modules fitted for full 0 - 1.5 MHz receive coverage, plus a previous owner had made some, Christmas-tree style, modules for 30, 17 and 12 metres. So, I did have a bit of luck after all the pain!

Regards,

Mark.

I have a TR7 transmit exciter board for sale that be of use to someone.
I purchased it from K3ICH some time ago but no longer need it as I am selling the TR7, serial 4566.
If interested please contact me off line at? hpolkscw@....
Harold
N3HP

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Paul

Jim,

No way I'm going to use regular DeOxit!? I'm planning to devote tomorrow to working on the TR-7 so hopefully I can find the issue.
73, Bill NX0T

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The weird part is the rod doesn't look bent and there is no stuff loose inside the envelope. That's the first thing I looked for. I wouldn't think that the plate structure has enough mass to bend that thick rod that much, but maybe. And who put the yellow dot on it and stuck it the amp? The current owner wasn't even sure there were tubes in it, he sent along a set of new Chinese tubes for it.

73

-Jim
NU0C

On Sun, 11 Feb 2024 03:59:06 +0000 (UTC)
"Evan via groups.io" <k9sqg@...> wrote:

Jim,
I have a similar one too. ?The plate "stud" or rod was bent due to excessive force during shipping. ?Typically there will also be some flakes of the grid floating around too if the tube is not new.
Getting an insurance claim settled was quite a saga.
73,
Evan
On Saturday, February 10, 2024 at 10:37:19 PM EST, Jim Shorney <jimnu0c@...> wrote:


OK guys, have a look at this close-up pic of a 3-500z. This was found in an L7 (not mine). That's not lens distortion or an optical illusion, it really looks like that. makes noise when you pick it up and move it around. This LOOKS like brand new tube. As does its partner. 93xx date codes, paint that looks fresh and not burned. I can't figure how this got out of the factory this way but it doesn't look like shipping damage to me. The wonky tube has a yellow dot sticker on top like someone knew...? Wow. The moral of this story is always give unknown tubes a good look before you power them up. I hate to think of what would have happened if I had hit this one with full HV.

--

73

-Jim
NU0C

OK guys, have a look at this close-up pic of a 3-500z. This was found in an L7 (not mine). That's not lens distortion or an optical illusion, it really looks like that. makes noise when you pick it up and move it around. This LOOKS like brand new tube. As does its partner. 93xx date codes, paint that looks fresh and not burned. I can't figure how this got out of the factory this way but it doesn't look like shipping damage to me. The wonky tube has a yellow dot sticker on top like someone knew... Wow. The moral of this story is always give unknown tubes a good look before you power them up. I hate to think of what would have happened if I had hit this one with full HV.


--

73

-Jim
NU0C

Does anyone have a RV7 front panel they are willing to sell?


73

Stan
KM4HQE

Hi Mike

Good work. Just a shorted coax, go figure. Was it the aspect of long term teflon creep that let those sharp shield wire strands work there way thru the dielectric ? Those measurements are very good. Receiver is as hot as a pistol, as good as repeater receivers measure. Looks like 5 or 6 poles total in the front end so very good for intermod for a (at the time) mobile multiband rig. Had my 2M single bander in the car when I commuted and would work 146.52 simplex along the long 80 mile commute. Rig was 35 years old then and never missed a beat. Was working a ham 60+ miles away on 146.52 simplex with me being mobile and a 5/8 wavelength mag mount on the roof. No amp, just the rigs 25 watts. I could copy him when I was crossing the Tappanzee Bridge NY and the other station was just north of Atlantic City NJ. What are you using for PL on the UV3's ?

Paul - W2NMI

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Paul and group…

Hi Mike. Looking at the IF/Discriminator/Audio board schematic, a 10.7 Mhz, 3 mv RF level (signal generator input) at the input side of the pin diode CR301 will produce 100 mVp-p at the drain side of Q300. This may be an easy, useful sanity check for confirming if the back end after the mixer is meeting spec. The first callout is somewhat unclear as these signal level callouts from Drake have been expressed as Peak to Peak. The 3 mv input level is labeled as "signal generator", thus would be Vrms. Hypothesis - could be a bad leaky pin diode (CR301, one example) or the diode not fully forward biased and attenuating signal or some other flaw in the back end ?

Paul - W2NMI

?