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I can’t find any specs on the Tenma 72-460. Tenma makes decent equipment, but the 72-460 may not be as sensitive as laboratory grade instruments from a variety of manufacturers, including HP.

The HP 5385A is a nice counter. It is essentially an updated version of the 5305B and is just a bit more sensitive at 15mV RMS vs 20mV. I have been using a 5305B, which was made in the mid '70's,

The counter is a Tenma 72-460 that a friend lent me.? I do not know it's specs,? Yes the 10V is adjusted properly.

*** I scored an HP 5385A on Ebay specifically for this job. Sensitivity of 15mV RMS. I also have a cheap GPSDO for checking the counter. - Jerry, KF6VB

Excellent Jim, thanks very much. 73 de Raoul CE3RY

No. Pin 8 is the common ground of all the buffers if the ULN2003 chip. You can test the LED segments by BRIEFLY grounding, one at a time, pins 10 through 16 of U9032. Doing so will illuminate the

Just a guess, but how sensitive is your counter. The 5.645 MHz signal on Pin-40 is speced at 80mV P-P (57mV RMS) and is often quite a bit less in some TR7’s. You need a counter that can read a

Hi Ed, You want to start at the tail end of the R-4C. Pull the last IF tube that is a pain to remove. If the static does not go away, you know it is either the product detector or the audio

True that, but he is following the alignment instructions in the service manual which has specific requirements. 73 -Jim NU0C "Bob Loving" <bob.loving@...> wrote:

Did you ensure that the +10 was adjusted spot on first? You may need to play with the value of C1029 a bit. That's why it is a factory selected value, it it compensates for variations in other

If I remember correctly, Bill, the frequency is dependent upon the mode of operation. The frequency shifts above or below the center 5.645000-MHz frequency of the various mode filters to place the

A bad/leaky power supply filter cap could be the culprit, especially in the +14v line. Is it there with no antenna connected? How about with volume at zero? -- 73 de Mike, W1NR THAT was the

I had a noisy V4, 6BA6, IF Amplifier. Bob K9JU

Folks, I have a lot of the frying egg/static noise in my R-4C. I am using the Sherwood third mixer mod so don't have the usual suspect third mixer tube.? What else could be the source of that

I finally had a chance to use a decent frequency counter today. The 40 MHz oscillator is now spot on 40 MHZ and the VCXO is right on 53.695 MHz.? But the 8.05 MHz oscillator still will not quite get

Hi All, I'm trying to repair a DR7 board and I would like to "turn on" all LED segments. From the diagram, I believe that grounding pin 8 of U9032 might do it. As I don't want to ruin anything on the

Well, this is vexing, The Drake AGC circuit is very high impedance: on the order of megohms. It is employed to control the gain of the various stages by changing the bias voltage. It has been

Okay quick info on progress on the saga... Replaced V4&V5 with 2 NOS tubes, that brought the meter down from ~5-6 S units to ~4 S units, still the zero pot needs to be maxed/minimize depending how we

Been there. Did that. Spot on (slang for absolutely perfect). All my TR7s will get this mod. 73, -Glenn/ WB0DKT

Hi Raoul, Nice to see you are still at it. You will be better off with the version 2 predriver. 95 Watts on 15m is a good sign. If you have not seen this yet, here is a discussion of the V2 board