On 2/25/24 09:06, Brian Tibbert wrote:

Hi all,
I am currently trying to rebuild a 2AC crystal calibrator that has
been butchered by a previous owner.
I have stripped? it down to the bare circuit board, and? would?
appreciate a picture of the component layout as original.
Does any member have a photo that they could upload to help me.
Thanks
Brian
G3RKZ

Don't know if this is what you are looking for, but here's a couple of pics.

73

Stan
KM4HQE

And again with my typo fixed. I proofread it, honest!



On Sun, 25 Feb 2024 11:51:18 -0600
"Jim Shorney via groups.io" <jimNU0C@...> wrote:

I've updated K4JNG's digital board schematic image with the in circuit test points flagged and the optical interrupter part number added.

--

73

-Jim
NU0C

I've updated K4JNG's digital board schematic image with the in circuit test points flagged and the optical interrupter part number added.

--

73

-Jim
NU0C

That's good price. There are two on eBay for $11 and $15. I may have to buy a pair for spares. Thanks for the info.

73

-Jim
NU0C

On Sat, 24 Feb 2024 20:45:35 -0800
"K6OXN Bob" <bobk6oxn@...> wrote:

I also forgot to tell everyone that Green Brook Electronics is the source of the Optical Interrupters for the RV-75.? Part # is OPB813S which are $5 each shipping is $7.99

73? Bob

OK, good. That is pointing to the optical interrupter. It may have been useful to report the actual minimum and maximum voltages coming out of the interrupter since this is essentially a analog to digital converter. It would be interesting to know which half of the interrupter failed. P102 pins 2 and 7 would tell us if the LEDs are drawing current.

Good work on finding the replacement. My next question would have been are there any numbers on the interrupter. Don't forget to check the bias and mechanical adjustment after you put the new one in.

73

-Jim
NU0C

On Sat, 24 Feb 2024 20:40:15 -0800
"K6OXN Bob" <bobk6oxn@...> wrote:

I did follow the schematic, and I apologize for not reporting the voltage readings. TP101 reads 1.112 vdc and TP102 reads 8.31 vdc. TP101 does not vary when turning the tune dial, but TP102 varies when I turn the dial.? U101 pin 1 reads 1.112 vdc and pin 5 reads 5.41 vdc and pin 1 does not change with movement of the tune dial, while pin 5 does vary. This led me to believe the Optical Interrupter was at fault since I can change the direction up or down with changing U1 and U2 of the optical device.? Again I apologize and will try and keep everyone informed in the future.

--

73

-Jim
NU0C

开云体育

I also forgot to tell everyone that Green Brook Electronics is the source of the Optical Interrupters for the RV-75.? Part # is?OPB813S which are $5 each shipping is $7.99

73? Bob

I did follow the schematic, and I apologize for not reporting the voltage readings. TP101 reads 1.112 vdc and TP102 reads 8.31 vdc. TP101 does not vary when turning the tune dial, but TP102 varies when I turn the dial.? U101 pin 1 reads 1.112 vdc and pin 5 reads 5.41 vdc and pin 1 does not change with movement of the tune dial, while pin 5 does vary. This led me to believe the Optical Interrupter was at fault since I can change the direction up or down with changing U1 and U2 of the optical device.? Again I apologize and will try and keep everyone informed in the future.

If you want to help please look at the schematic.

73

-Jim
NU0C

On Sat, 24 Feb 2024 19:33:52 +0000
"Clint VE3CMQ" <ve6cmm@...> wrote:

Hi Bob,

It sounds to me that either the emitter or detector on the one channel of the encoder isn’t working. It might be easy to repair this problem. I don’t have an optical encoder like the one in the RV75 to look at though. The emitters will likely be infrared LED’s and the detectors light sensitive diodes. I doubt if photo resistors would be used as likely too slow for an encoder.

73, Clint, VE3CMQ

From: [email protected] <[email protected]> On Behalf Of K6OXN Bob via groups.io
Sent: Saturday, 24 February 2024 13:28
To: [email protected]
Subject: Re: [DRAKE-RADIO] RV-75 only decrements

Well by taking the Optical Interrupter apart and reversing the 2 elements, now the unit increments only. Will keep everyone informed after getting them and doing another calibration.
_._,_._,_

--

73

-Jim
NU0C

Did you make any of the voltage measurements that I asked for? Voltages on pins 2 and 7 of P102 could be helpful also. Don't assume that the part is bad just because you moved it. You could still have a connection issue somewhere. If it turns out to be so it may be possible to disassemble it and replace what is bad.

I'm trying hard to help you here but it's really hard to troubleshoot remotely without getting any feedback of data that I asked for.

73

-Jim
NU0C

On Sat, 24 Feb 2024 11:28:29 -0800
"K6OXN Bob" <bobk6oxn@...> wrote:

Well by taking the Optical Interrupter apart and reversing the 2 elements, now the unit increments only. Will keep everyone informed after getting them and doing another calibration.

--

73

-Jim
NU0C

开云体育

Well by taking the Optical Interrupter apart and reversing the 2 elements, now the unit increments only. Will keep everyone informed after getting them and doing another calibration.

Nice Loop. I'm planning a somewhat larger one. So far, I only have
the capacitor. 15-250pF @ 45kV.

- Jerry, KF6VB

Thanks for the pic and info Mark. That looks like something I would build! I've been meaning to work up something to carry my LAN-IQ portable SDR receiver around. Yes, bearings from two or more locations, a.k.a. triangulation, is a common method of resolving the location of an RF source. I once tracked down the location of a fox in a rare 80m fox hunt here by using the null off the end of the whip antenna of a portable SW receiver while the other hunters were chasing ghosts at the other end of the county. They were all VHF hunters...

73

-Jim
NU0C

On Sat, 24 Feb 2024 02:16:17 -0800
"atlasstuff" <g4fph@...> wrote:

Jim,

Thank goodness the interference was gone the next day and has not returned. I hope it never does. Sounded like one of these horrible Chinese, switch mode / pulsed chargers for automotive batteries. So, my loop stayed under the EMC emergency / break glass cover in the shack - HI!

Please find attached a picture of the loop. It's very simple but very effective, with deep nulls. Built on a plastic, electric fence post, to which I also attach my Kenwood TH-F6 HT as detector / receiver, and designed to be held in one hand while walking about. With no amplification, the combination is easily sensitive enough to hear signals and noises. One enhancement I have thought about is something to resolve the ambiguity of having two nulls per 360-degree of revolution. In practice, however, I have not found this essential as, by making an educated guess / walking about awhile, I have been able to work out which of the two possible directions noises come from.

I keep the loop tuned for the 80-metre band. It comprises three turns of single-strand, insulated wire at around 270 mm diameter. Tuned with the parallel combination of around 210 pF, plus the air variable, which is probably set to 100 pF for mid-band. The pick up loop is one turn of the same stiff wire at around 100 mm diameter, direct connected to a short length of coax terminated with an SMA to connect to the radio.

I commend having one, or similar, to all that try to make HF radio work in non-ideal environments. Like we used to keep spare fanbelts in the boots / trunks of our cars as a guarantee that we would never need them!

Regards,

Mark, G4FPH.

--

73

-Jim
NU0C

Good morning to all on the list! After much thought I have decided to part with my TR4C
and RV 4C. I bought these from GAREY BARRELL back in 2010 during a visit to his QTH in Glen Allen Va . It was gone over by Mike N0BXE in 2022 he made it as good as new ….Iv used it on 40 CW & SSB MANY TIMES. I use an ASTATIC D 104 Golden Eagle amp mic with it with no issues and good audio reports I’m throwing that in as well the AC 4 has been recapped by me and have no real problems with the rig.
Every thing plus GAREY’s CD’s and written manuals are included.
Asking 450$ plus 150$ shipping
Interested parties can contact me off list at my email address
Bill
WB2UFC

Jim,

Thank goodness the interference was gone the next day and has not returned. I hope it never does. Sounded like one of these horrible Chinese, switch mode / pulsed chargers for automotive batteries. So, my loop stayed under the EMC emergency / break glass cover in the shack - HI!

Please find attached a picture of the loop. It's very simple but very effective, with deep nulls. Built on a plastic, electric fence post, to which I also attach my Kenwood TH-F6 HT as detector / receiver, and designed to be held in one hand while walking about. With no amplification, the combination is easily sensitive enough to hear signals and noises. One enhancement I have thought about is something to resolve the ambiguity of having two nulls per 360-degree of revolution. In practice, however, I have not found this essential as, by making an educated guess / walking about awhile, I have been able to work out which of the two possible directions noises come from.

I keep the loop tuned for the 80-metre band. It comprises three turns of single-strand, insulated wire at around 270 mm diameter. Tuned with the parallel combination of around 210 pF, plus the air variable, which is probably set to 100 pF for mid-band. The pick up loop is one turn of the same stiff wire at around 100 mm diameter, direct connected to a short length of coax terminated with an SMA to connect to the radio.

I commend having one, or similar, to all that try to make HF radio work in non-ideal environments. Like we used to keep spare fanbelts in the boots / trunks of our cars as a guarantee that we would never need them!

Regards,

Mark, G4FPH.

Glenn,

Yes, 1N4007 performance as PIN at 30 MHz in that regard is not great. The measurements documented on the page below suggest around 6.5 pF at 10 MHz with some modest level of reverse bias, which seems in line with the datasheet. I wonder whether this issue - even with the original PIN diodes - was the reason that Drake included two in series in the receive path?



As my junk box has no PIN diodes in it, I shall check to see what can be purchased.

Regards,

Mark, G4FPH.