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This is my third unit (the first 2 failed). I ordered this one from AliExpress. It arrived from China in 8 days and continues to operate properly. It was 1/3 the price Amazon was showing and was a hassle-free purchase. I received excellent updates on status and location of the unit during transit from China. This is the first time I have used AliExpress, and I was impressed.

This unit is about 3 dB more sensitive than the previous two units that I purchased from Amazon and is less sensitive to spurs on the R4-C “ INJ” line. Freq readings are stable on all bands.

I installed a J310 JFET buffer to drive the counter. Although the insertion loss of this device ranged from 4-5 dB over the freq range of interest (2-34 MHz), there was still at least 6 dB of margin above the threshold of the counter, so I didn’t feel additional gain was necessary.

This unit also had the problem with the color code on the provided cable for the signal input- red is gnd and black is the signal line. The color code for the DC power connector is correct.

Bill N0CU

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Bill N0CU

HI Bill!

Would you happen to have the schematic of the J310 buffer circuit?

I've been using a plj6led for quite some time, but loose lock on counter when transmitting on 15/10Meters, so would like to try a j310 buffer solution.

Tried to use a couple of 2n2222's but result was really not that good.

Would be great if you could share!

Thanks, 73's de oz8abr Michael.

On Thu, May 15, 2025 at 7:06?PM Bill Leonard N0CU via <billincolo73=[email protected]> wrote:

This is my third unit (the first 2 failed). I ordered this one from AliExpress. It arrived from China in 8 days and continues to operate properly. It was 1/3 the price Amazon was showing and was a hassle-free purchase. I received excellent updates on status and location of the unit during transit from China. This is the first time I have used AliExpress, and I was impressed.

This unit is about 3 dB more sensitive than the previous two units that I purchased from Amazon and is less sensitive to spurs on the R4-C “ INJ” line. Freq readings are stable on all bands.

I installed a J310 JFET buffer to drive the counter. Although the insertion loss of this device ranged from 4-5 dB over the freq range of interest (2-34 MHz), there was still at least 6 dB of margin above the threshold of the counter, so I didn’t feel additional gain was necessary.

This unit also had the problem with the color code on the provided cable for the signal input- red is gnd and black is the signal line. The color code for the DC power connector is correct.

Bill N0CU

--

Bill N0CU

Michael,

Attached is a copy of the pdf that I pulled the circuit from.

If by "lose lock" you mean that the freq display is erratic, I would also recommend that you check the alignment on those bands. There is a spur on the INJ line that is 5.645 MHz above the INJ?frequency. As you move to the higher bands, that spur moves closer to the INJ signal and if high enough can cause an unstable?display. This spur caused unstable readings on 10 M with one of the counters. It was only 8 dB below the INJ signal. When I realigned that band I was able to get the spur down 15 dB and the display was stable. Also, there is a difference among the counters with respect to how sensitive they are to this spur. My new counter can deal with that spur when it is only 5 dB below the INJ signal level.

Hope this helps. Let me know if you have any more questions.

Bill N0CU

On Thu, May 15, 2025 at 11:57?AM Michael Jensen via <kavigal=[email protected]> wrote:

HI Bill!

Would you happen to have the schematic of the J310 buffer circuit?

I've been using a plj6led for quite some time, but loose lock on counter when transmitting on 15/10Meters, so would like to try a j310 buffer solution.

Tried to use a couple of 2n2222's but result was really not that good.

Would be great if you could share!

Thanks, 73's de oz8abr Michael.

On Thu, May 15, 2025 at 7:06?PM Bill Leonard N0CU via <billincolo73=[email protected]> wrote:

This is my third unit (the first 2 failed). I ordered this one from AliExpress. It arrived from China in 8 days and continues to operate properly. It was 1/3 the price Amazon was showing and was a hassle-free purchase. I received excellent updates on status and location of the unit during transit from China. This is the first time I have used AliExpress, and I was impressed.

This unit is about 3 dB more sensitive than the previous two units that I purchased from Amazon and is less sensitive to spurs on the R4-C “ INJ” line. Freq readings are stable on all bands.

I installed a J310 JFET buffer to drive the counter. Although the insertion loss of this device ranged from 4-5 dB over the freq range of interest (2-34 MHz), there was still at least 6 dB of margin above the threshold of the counter, so I didn’t feel additional gain was necessary.

This unit also had the problem with the color code on the provided cable for the signal input- red is gnd and black is the signal line. The color code for the DC power connector is correct.

Bill N0CU

--

Bill N0CU

Thanks Bill, appreciate.

I will investigate further, alignment may be it, who knows, first of all I need to wait for the mail man to show up with some capacitors as I've been experimenting with new finals(non Sylvania) so got some?neutralization issues to deal with first of all.

and yes erratic(unstable) display reading on 15/10meters was the correct wording.

73's de Michael - oz8abr

On Thu, May 15, 2025 at 9:03?PM Bill Leonard N0CU via <billincolo73=[email protected]> wrote:

Michael,

Attached is a copy of the pdf that I pulled the circuit from.

If by "lose lock" you mean that the freq display is erratic, I would also recommend that you check the alignment on those bands. There is a spur on the INJ line that is 5.645 MHz above the INJ?frequency. As you move to the higher bands, that spur moves closer to the INJ signal and if high enough can cause an unstable?display. This spur caused unstable readings on 10 M with one of the counters. It was only 8 dB below the INJ signal. When I realigned that band I was able to get the spur down 15 dB and the display was stable. Also, there is a difference among the counters with respect to how sensitive they are to this spur. My new counter can deal with that spur when it is only 5 dB below the INJ signal level.

Hope this helps. Let me know if you have any more questions.

Bill N0CU

On Thu, May 15, 2025 at 11:57?AM Michael Jensen via <kavigal=[email protected]> wrote:

HI Bill!

Would you happen to have the schematic of the J310 buffer circuit?

I've been using a plj6led for quite some time, but loose lock on counter when transmitting on 15/10Meters, so would like to try a j310 buffer solution.

Tried to use a couple of 2n2222's but result was really not that good.

Would be great if you could share!

Thanks, 73's de oz8abr Michael.

On Thu, May 15, 2025 at 7:06?PM Bill Leonard N0CU via <billincolo73=[email protected]> wrote:

This is my third unit (the first 2 failed). I ordered this one from AliExpress. It arrived from China in 8 days and continues to operate properly. It was 1/3 the price Amazon was showing and was a hassle-free purchase. I received excellent updates on status and location of the unit during transit from China. This is the first time I have used AliExpress, and I was impressed.

This unit is about 3 dB more sensitive than the previous two units that I purchased from Amazon and is less sensitive to spurs on the R4-C “ INJ” line. Freq readings are stable on all bands.

I installed a J310 JFET buffer to drive the counter. Although the insertion loss of this device ranged from 4-5 dB over the freq range of interest (2-34 MHz), there was still at least 6 dB of margin above the threshold of the counter, so I didn’t feel additional gain was necessary.

This unit also had the problem with the color code on the provided cable for the signal input- red is gnd and black is the signal line. The color code for the DC power connector is correct.

Bill N0CU

--

Bill N0CU