Date   

Re: UBITX. FT8 heat sink requirements #ft8 #ubitx

Gordon Gibby
 

I doubt it seriously. Almost all Riggs, have to be Der ated a bit for continuous duty.   


On Jun 18, 2020, at 17:16, Mick <Mgsebele@...> wrote:

Aaron,
I run FT8 all the time without any over heat problems.
--
 

73
Mick VA3EPM 


Re: UBITX. FT8 heat sink requirements #ft8 #ubitx

Mick
 

Aaron,
I run FT8 all the time without any over heat problems.
--
 

73
Mick VA3EPM 


Re: Opposite side band rejection ubitx V6

Dale Parfitt
 

Thank you Gary,

My apologies for not doing my homework. Much appreciated.

Dale W4OP

 

From: BITX20@groups.io [mailto:BITX20@groups.io] On Behalf Of Gary Anderson
Sent: Thursday, June 18, 2020 3:57 PM
To: BITX20@groups.io
Subject: Re: [BITX20] Opposite side band rejection ubitx V6

 

On Thu, Jun 18, 2020 at 11:38 AM, Dale Parfitt wrote:

Hi Allison et al,

What  is the design in/out impedance of the crystal filter?

Dale,
SSB filter is 200 ohms per the circuit description
https://www.hfsignals.com/index.php/ubitx-circuit-description/
Rgds,
Gary


Re: Opposite side band rejection ubitx V6

Gary Anderson
 

On Thu, Jun 18, 2020 at 11:38 AM, Dale Parfitt wrote:

Hi Allison et al,

What  is the design in/out impedance of the crystal filter?

Dale,
SSB filter is 200 ohms per the circuit description
https://www.hfsignals.com/index.php/ubitx-circuit-description/
Rgds,
Gary


Re: UBITX. FT8 heat sink requirements #ft8 #ubitx

Aaron K5ATG
 

I'm guessing that the uBitx V6 transistors and heat sinks are good enough for the digital modes also?
--
'72
Aaron Scott
QRPARCI# 16443
GQRP# 16389
4SQRP # 1080


Re: Opposite side band rejection ubitx V6

Dale Parfitt
 

Hi Allison et al,

What  is the design in/out impedance of the crystal filter?

 

Dale W4OP

 

From: BITX20@groups.io [mailto:BITX20@groups.io] On Behalf Of barry halterman
Sent: Thursday, June 18, 2020 2:29 PM
To: BITX20@groups.io
Subject: Re: [BITX20] Opposite side band rejection ubitx V6

 

Allison, as always, appreciate your input. I have noticed that between my V4 and V6 there seems to be a noticable difference. The V4 tends to be better. I might try the grounding of the cases or change the termination caps to 100pf in my V6.

Thanks

Barry

K3bo

 

 

On Thu, Jun 18, 2020, 1:24 PM ajparent1/kb1gmx <kb1gmx@...> wrote:

I got to play with a bunch of them last year and the result...

The filters vary enough that a good one can easily exceed 40db and the
average was 35db.  One I hand optimized the filter did hit 45dB.

Overall of the filters seems rather narrow and those I measured were
under 2.1KHz wide A wider 2.4 to 2.7 KHz woudl work and sound
better.  The other was soem the caps used to load/tune the fitler
were less than optimal in value.  In all grounding the cans helped
between 2-3 db in the overall shape and opposing sideband rejection.

My suggestion is unless you into building and tunign crystal fitlers 
and have the gear leave it be.  You can break it faster than improve it.

Allison
---------------------------------
No direct email, it goes to bit bucket due address harvesting in groups.IO


Re: Opposite side band rejection ubitx V6

barry halterman
 

Allison, as always, appreciate your input. I have noticed that between my V4 and V6 there seems to be a noticable difference. The V4 tends to be better. I might try the grounding of the cases or change the termination caps to 100pf in my V6.
Thanks
Barry
K3bo


On Thu, Jun 18, 2020, 1:24 PM ajparent1/kb1gmx <kb1gmx@...> wrote:
I got to play with a bunch of them last year and the result...

The filters vary enough that a good one can easily exceed 40db and the
average was 35db.  One I hand optimized the filter did hit 45dB.

Overall of the filters seems rather narrow and those I measured were
under 2.1KHz wide A wider 2.4 to 2.7 KHz woudl work and sound
better.  The other was soem the caps used to load/tune the fitler
were less than optimal in value.  In all grounding the cans helped
between 2-3 db in the overall shape and opposing sideband rejection.

My suggestion is unless you into building and tunign crystal fitlers 
and have the gear leave it be.  You can break it faster than improve it.

Allison
---------------------------------
No direct email, it goes to bit bucket due address harvesting in groups.IO


Re: Opposite side band rejection ubitx V6

ajparent1/kb1gmx <kb1gmx@...>
 

I got to play with a bunch of them last year and the result...

The filters vary enough that a good one can easily exceed 40db and the
average was 35db.  One I hand optimized the filter did hit 45dB.

Overall of the filters seems rather narrow and those I measured were
under 2.1KHz wide A wider 2.4 to 2.7 KHz woudl work and sound
better.  The other was soem the caps used to load/tune the fitler
were less than optimal in value.  In all grounding the cans helped
between 2-3 db in the overall shape and opposing sideband rejection.

My suggestion is unless you into building and tunign crystal fitlers 
and have the gear leave it be.  You can break it faster than improve it.

Allison
---------------------------------
No direct email, it goes to bit bucket due address harvesting in groups.IO


Re: Opposite side band rejection ubitx V6

barry halterman
 

Evan, I played around with the BFO but that really did not help much and like you said the tone quality went down hill. I was just curious.
Thanks
K3bo

On Thu, Jun 18, 2020, 12:27 PM Evan Hand <elhandjr@...> wrote:
It has been a while since I did the measurements, so I may be susceptible to a senior moment.  It does sound about right.  I believe I was adjusting the BFO to trade-off opposite sideband suppression with tonal quality.  I would up somewhere around that figure.  I was trying to hit 43db, but the tone quality was really bad.

FWIW
73
Evan
AC9TU


Re: Opposite side band rejection ubitx V6

Evan Hand
 

It has been a while since I did the measurements, so I may be susceptible to a senior moment.  It does sound about right.  I believe I was adjusting the BFO to trade-off opposite sideband suppression with tonal quality.  I would up somewhere around that figure.  I was trying to hit 43db, but the tone quality was really bad.

FWIW
73
Evan
AC9TU


Opposite side band rejection ubitx V6

barry halterman
 

May I ask what  the opposite side band rejection typically is on the ubitx? Does 35db seem about right?
Barry
K3bo


Re: FS V6

John Veach <ke4d@...>
 

Sold. 


Re: RFI on 2 meters from uBitx

Evan Hand
 

I checked, and I do have the 2 meter signal of the SI5351 3rd harmonic.  It goes away on CW TX, confirming to me it is the LO Clock2 signal, as that is changed to the actual frequency on CW TX.

As Jay noted, it is quite strong.  My ubitx v4 has the relays replaced, and I have verified the harmonic reduction after the replacement.  It is in a metal case, however, I do not have a good ground in the shack, just a copper water pipe. If I use my hand as a temporary RF choke around the antenna coax, I can get a significant reduction in the signal strength on the Kenwood TM-D710G, the squelch will drop out.  Based on my simple test, ferrites on all lines into and out of the rig would be the answer.

Best guesses at this point.
73
Evan
AC9TU


Re: ANTUINO antenna analzer CERTAIN CLARIFICATIONS REG

R. Tyson
 

In response to the original post....

Calculating the length of a dipole from the formula is the first stage and gives you an approximate length. It is best to cut the dipole longer than the calculated length and then trim a bit off each end until you get it to resonance.

As others have mentioned, the antenna will be affected by it's suroundings and also any bending out of shape that may be done to get it to fit into the space available.

Mounting the dipole as an inverted  V  will also affect the resonant length and the feed point impedance. The height of the antenna above ground also affects these things.

So you have it up as a inverted  V  fan dipole which appears to be cut too short to resonate where you want it. Pity as it is easier to cut bits off than to add bits to lengthen them.

You need to add wire, allow extra so you can trim it back, you don't want to keep soldering extra bits on. Do this with both the 40 and 20 metre sections ( I think that's what you originally cut it for). As it's a fan dipole start with the longest, 40M, part and slowly trim each end back until your NanoVNA shows you have it resonant where you want it to be.
Once you have the longest section trimmed then do the same with the shorter 20 metre section. There will be some interaction between the 2 fan dipoles and you should trim the longest one and only then trim the shorter one. Then check where the resonance is on both bands again.... you may need some more slight trimming due to their interaction but
chances are it may be O.K. and the job's done.

If you check the SWR it should be below 2:1, it will probably be lower but it would be O.K at that level. 1:1 SWR is very nice but anything below 2:1 will get you on the air.

Reg                        G4NFR


Re: RFI on 2 meters from uBitx

Dale Parfitt
 

Hi Evan,

While there can be a good deal of math involved to optimize ferrite common mode choking impedance, it  so easy to do trial and error that for most cases we can forgo the math.

I had  a serious distortion issue when I was connecting my Drake TR-7 to my solid state SPE Expert HF amplifier. My K3 had always played beautifully with the SPE as had  a number of other boatanchor rigs- both vacuum tube and solid state. I tried ALC, no ALC, all sorts of fixes. The issue turned out to be common mode on the PTT line from the rig to the amplifier. Who would have thunk it.

 

Dale W4OP

 

From: BITX20@groups.io [mailto:BITX20@groups.io] On Behalf Of Evan Hand
Sent: Thursday, June 18, 2020 8:45 AM
To: BITX20@groups.io
Subject: Re: [BITX20] RFI on 2 meters from uBitx

 

Dale's message prompted me to think of other cables that run near the Raduino.  By chance are you using CAT from the rig?   Snap a ferrite on it and any digital mode cables. 

Dale,
A good suggestion for the ferrites.  I already have them on my rigs because of RF feedback.

73
Evan
AC9TU


Re: RFI on 2 meters from uBitx

Evan Hand
 

Dale's message prompted me to think of other cables that run near the Raduino.  By chance are you using CAT from the rig?   Snap a ferrite on it and any digital mode cables. 

Dale,
A good suggestion for the ferrites.  I already have them on my rigs because of RF feedback.

73
Evan
AC9TU


Re: RFI on 2 meters from uBitx

Dale Parfitt
 

Regarding the 2M issue, you might also try disconnecting your HF antenna and see if the issue goes away. If it does, then some #43 snap on ferrites right where the antenna coax exits the BitX should help- same for the key, mic and power leads. Of course, if the rig is not in a metal cabinet then all bets are off.

 

Dale W4OP

 

From: BITX20@groups.io [mailto:BITX20@groups.io] On Behalf Of Evan Hand
Sent: Thursday, June 18, 2020 8:17 AM
To: BITX20@groups.io
Subject: Re: [BITX20] RFI on 2 meters from uBitx

 

Jay,
Ensuring that it is installed in a metal case that is grounded is the only thing that I could see helping.  Are there any modifications installed?

What you are seeing is the 3rd harmonic of the Clock2 out of the SI5351 that is used in the first mixer to convert the incoming RF to the 45 MHz IF frequency.  That is not a mixing product.  It is the local oscillator for the conversion to 45 MHz IF.  Those signal traces are fairly short, so not much of an antenna.  Also, since it is on both transmit and receive, I doubt that the first mixer is damaged. 

I will see if one of my ubitx has the same issue.

73
Evan
AC9TU


Re: RFI on 2 meters from uBitx

Evan Hand
 

Ashhar Farhan and Raj,

The original email stated that it was there on both transmit and receive.  I think that should rule out the relays, any of the transmitter amplifier stages, and the antenna match.  I guess it is possible that a bad match could affect the 30 Mhz LPF at the input to the first IF,  Still, the double-balanced mixer should isolate the LO from the RF port.

Am I missing something?
73
Evan
AC9TU


Re: RFI on 2 meters from uBitx

Ashhar Farhan
 

It could be lack of shielding on the two meter rig too. We have swept the output of ubitx, there are very very small spurs at 2 meters. Indeed, it would be a wonderful surprise to find the venerable IRF510 shaking a leg on 144 mhz.
I hope 80 meter antenna is well matched.

On Thu 18 Jun, 2020, 5:41 PM Raj vu2zap, <rajendrakumargg@...> wrote:
You could try replacing relays KT1/2/3 with Axicom RF relays, that should reduce this.
Check earlier posts for details.

Raj

At 18/06/2020, you wrote:
>I have been experiencing RFI on the 2 meter band when my V3 is tuned to the upper end of 75 meters. I had my uBitx tuned to the TN Phone net at 3.980 MHz and my 2 meter rig tuned to my local repeater at 146.91 MHz. The 2 meter rig showed full scale receive, with no audio. I checked with my hand held and it was full scale at least 50 feet from the uBitx. The RFI exists when the uBitx is in RX as well as TX. Seems like a 3rd harmonic of a mixing product; (45 MHz+3.98 MHz) X 3 = 146.94 MHz
>
>Any ideas where or how to add shielding or if a component needs to be replaced?
>
>Thanks,
>Jay
>WS4JM





Re: RFI on 2 meters from uBitx

Evan Hand
 

Jay,
Ensuring that it is installed in a metal case that is grounded is the only thing that I could see helping.  Are there any modifications installed?

What you are seeing is the 3rd harmonic of the Clock2 out of the SI5351 that is used in the first mixer to convert the incoming RF to the 45 MHz IF frequency.  That is not a mixing product.  It is the local oscillator for the conversion to 45 MHz IF.  Those signal traces are fairly short, so not much of an antenna.  Also, since it is on both transmit and receive, I doubt that the first mixer is damaged. 

I will see if one of my ubitx has the same issue.

73
Evan
AC9TU