Re: ND6T AGC implementation for uBIT-X
Jerry you know the uBITx PA design is nothing like the WA2EBY design, so why would you expect the same result?? It escapes me why people bring this up.? The commonality is that they use the same PA transistors and that¡¯s pretty much where it ends.? We¡¯ve both done simulations on both systems and understand the differences precisely (given the ¡°S¡± params we have). ? A closer study of the datasheets for the IRF & RD devices tell the story.? Failures in the IRF device is likely caused by the degree of coupling between the gate and drain.? Allison in another post wrote: ¡°This is more often seen with higher capacitance devices like IRF510.? The failure mechanism is with high RF voltages ?on the drain it¡¯s is coupled back to the gate by the gate to drain capacitance and if the source (driver) ?impedance is not low enough the gate can reach a voltage that exceeds its breakdown level ?(20V or less) this leads to gate oxide punch through and the device fails.¡± ? Now no one should be alarmed by this post.? If you treat your radio right, there will be no PA problems. ? ? Dr. William J. Schmidt - K9HZ J68HZ 8P6HK ZF2HZ PJ4/K9HZ VP5/K9HZ PJ2/K9HZ ? Owner - Operator Big Signal Ranch ¨C K9ZC Staunton, Illinois ? Owner ¨C Operator Villa Grand Piton ¨C J68HZ Soufriere, St. Lucia W.I. Rent it: Like us on Facebook! ? Moderator ¨C North American QRO Group at Groups.IO. ? email:? bill@... ? ?
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From: [email protected] [mailto:[email protected]] On Behalf Of Jerry Gaffke via Groups.Io
Sent: Sunday, April 29, 2018 11:24 AM
To: [email protected]
Subject: Re: [BITX20] ND6T AGC implementation for uBIT-X ? Like I said, most of the cooked IRF510 reports seem to be from twiddling bias pots,
not high SWR.? Can you point to a few posts that report otherwise?
When operating at 12v?
Of course there aren't any reports of failed RD16HHF1's.? There's likely fewer than a half dozen
who have bothered to swap them in, and all by folks well experienced with hacking at radios.
Good that you can report 20W continuous with a couple RD16HHF1's.
In my previous post, I quoted Allison as saying:
"My favorite is two in a push pull amp (K500r/wa2eby design) with 28V running about 55W on 40m
and 37W at 10M and after 6 years of wrong antenna and all sorts of usual havoc its still running with the same pair. "
Can your dual RD16HHF1's do that?
If IRF510's in push-pull can do that at 28V, why would that same configuration be even vaguely suspect at 12V?
You made a point a week or two ago that the IRF510's require more drive to get significant power out?at 30mhz.?
That's fair enough.? The uBitx drivers to that final are built on $0.03 2n3904's, I wouldn't expect great?
performance at 30mhz.? Those that really need 20W on 30mhz could do well to follow your lead with
the RD16HHF1's.? Or they could add Fidel's 2 caps and inductor to get reasonably even output from the uBitx.
Maybe add a WA2EBY dual IRF510 amp to use with their uBitx and get Allison's 37W at 30mhz.
?
I'm coming down a bit hard here because I see absolutely no reason to alarm
several thousand forum readers with the prospect of a smoking crater where their rig used to be.
The IRF510's at 12v seem quite bulletproof, and an excellent choice for a $109 rig.
All that said, experimentation with other totally different finals is most welcome.
Jerry, KE7ER
On Sun, Apr 29, 2018 at 08:21 am, K9HZ wrote: ¡°Exactly where did you find this data?¡±? Right here on the forum.? Multiple reports of IRF510 failures.? Not a single RD16HHF1 failure reported yet (now that doesn¡¯t mean it can¡¯t happen).? My own experience:? I unplugged the antenna at 20 watts while the transmitter was transmitting¡ it sat for several minutes while I took a phone call. It got hot but never failed.? I¡¯d love for someone to try that with the IRF510.? Bias is important only because there is no junction over-voltage protection.? So maybe there is a correlation between knowing how to replace the IRF device and not crank the bias pot up? ?
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Re: Please don't make Radiuno with CH340/CH341 chipsets any more! Or at least advertise that you do use them!
#radiuno
... and if you don¡¯t want to solder the tiny CP2102 chip, you can get it on a board, with everything you need to hook it up to your Arduino for $2 at Tayda:?
--
Karl Heinz - K5KHK
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Using Encoders with the Teensy and ?BITX
All:
Yesterday morning I had a lot more hair than I have today. I'm working with a KY-040 encoder which has a switch built into it. I'm also using a Teensy 3.6 instead of the Nano. The encoder has 5 pins on it: +, GND, SW, A, and B. Pins A and B are responsible for the pulse chain that can be read to determine the direction the encoder is being turned. I ran the switch pin (SW) to pin 2 on the Teensy and the series of 4 GND pins near one end of the board. Determining the direction worked flawlessly. The switch...not so much. I tried everything, checked with an ohm meter and it looked fine. I even switched it out with another encoder...no joy. While I was taking a lunch break, I was thinking...
You don't suppose...
Yep. Those GND pins are for a small prototyping area and have no relation to the digital pins on the board. They are completely independent. Yet another flat forehead mistake. Perhaps this can save some of you from going bald.
Jack, W8TEE
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Re: A steal for Arduino Experimenters
The description on-line specs it for 3.3V boards.? Is the one you are referring to different?
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Re: Finding your hex (and other) files
#bitx20
Opps...I misunderstood the problem.
Jack, W8TEE
On Sunday, April 29, 2018, 12:40:26 PM EDT, Bo Barry <wn4ghv@...> wrote:
Thanks so much Jack. I've often needed that info for other projects! I printed it out fo keep.
However, I was referring to Ian's precompiled hex files I couldn't find, because I was having trouble compiling/uploading them from the Arduino program.
The hex loader program worked fine on the one I found.
It turned out to be the nano bootloader problem!? ?I swear I had used the top option not the old bootloader option on previous occasions and now only the old one works.
At any rate, I'm now thoroughly enjoying Ian's work. The 20x4 I2c display works fine.
Thanks again.
Bo W4GHV
P.S. I have some spare parts left over from your nice QST XCVR project If anyone is interested. I can do inventory if needed.
]
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Re: No output on LSB but output fine on CW.
I believe Dave has identified your problem area, if you wired up your mic jack per the wire up instructions your Kenwood/ Beofang mic won¡¯t work. That mic has the audio/bias on the ring and ground on the sleeve the tip is not use for this purpose. So you¡¯ll need to wire your uBITX or BITX to reflect that configuration unless you are only going to use it with your BITX¡¯s. By the way also PTT is on the sleeve of the 2.5mm plug.
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On Apr 29, 2018, at 10:00, davesters@... wrote: I would bet that the mic socket is wired incorrectly. Two of the pins disconnect when the plug is inserted.
73
Dave
K0MBT
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I did Howard's mod by adding the calculated 27uH inductor in series with R86 and parallel caps of 220pF on R87 and R88. My power output change results: 7MHz from 12.5w to 14.5w 14MHz from 7w to 11.5w 21MHz from 4w to 8w 28MHz from 2w to 4w A very worthwhile mod for just 3 components. Nigel G4ZAL 
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Re: Please don't make Radiuno with CH340/CH341 chipsets any more! Or at least advertise that you do use them!
#radiuno
If D0 and D1 come out to a jack for the keyer paddle, can use the same jack for firmware downloads.?
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On Sun, Apr 29, 2018 at 09:47 am, Jerry Gaffke wrote:
And, should be possible to use D0 and D1 for other stuff when not downloading firmware.
Perhaps a good choice for paddle dot/dash digital inputs.
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Re: Please don't make Radiuno with CH340/CH341 chipsets any more! Or at least advertise that you do use them!
#radiuno
Could be that the Raduino's processor just gives access to the RX/TX UART pins, no USB chip on board at all.
Then use your choice of FTDI/Prolific/SiLabs in a cable adapter such as this:??
? ??
Or just go around the USB chip on the cheap Nano's,
should be trivial to do according to that webpage pointed to in my previous post.
And, should be possible to use D0 and D1 for other stuff when not downloading firmware.
Perhaps a good choice for paddle dot/dash digital inputs.
Jerry, KE7ER
On Sun, Apr 29, 2018 at 09:01 am, Paula Bailey-Stine wrote:
Probably the only chipsets that are a) legitimately inexpensive and b) work pretty much gracefully across all platforms seem to be the SiLabs CP2102 (which is honestly what I tend to use anymore with anything requiring a USB-to-serial connection--no issues with blacklisting, works pretty much out-of-the-box across OS's).? If the Raduino does end up redesigned, I'd humbly suggest using CP2102s :D
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Re: uBITX_CEC1.073_20I.hex
Ian, I'm marveling at your code! Fantastic.
I had seen your note about 5 hex files being available and I couldn't find them.
I was having problems with the source and couldn't upload them. Hence the look for your hex files.
The problem was the nano bootloader! Choosing the old option fixed things! My 20x4 I2c works fine.
Now I can enjoy you work again and add minor options to it. I like to P&M stuff (plagiarize & modify). :)
73, Bo W4GHV since '54
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Re: Finding your hex (and other) files
#bitx20
Thanks so much Jack. I've often needed that info for other projects! I printed it out fo keep.
However, I was referring to Ian's precompiled hex files I couldn't find, because I was having trouble compiling/uploading them from the Arduino program.
The hex loader program worked fine on the one I found.
It turned out to be the nano bootloader problem!? ?I swear I had used the top option not the old bootloader option on previous occasions and now only the old one works.
At any rate, I'm now thoroughly enjoying Ian's work. The 20x4 I2c display works fine.
Thanks again.
Bo W4GHV
P.S. I have some spare parts left over from your nice QST XCVR project If anyone is interested. I can do inventory if needed.
]
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Re: ND6T AGC implementation for uBIT-X
Like I said, most of the cooked IRF510 reports seem to be from twiddling bias pots,
not high SWR.? Can you point to a few posts that report otherwise?
When operating at 12v?
Of course there aren't any reports of failed RD16HHF1's.? There's likely fewer than a half dozen
who have bothered to swap them in, and all by folks well experienced with hacking at radios.
Good that you can report 20W continuous with a couple RD16HHF1's.
In my previous post, I quoted Allison as saying:
"My favorite is two in a push pull amp (K500r/wa2eby design) with 28V running about 55W on 40m
and 37W at 10M and after 6 years of wrong antenna and all sorts of usual havoc its still running with the same pair. "
Can your dual RD16HHF1's do that?
If IRF510's in push-pull can do that at 28V, why would that same configuration be even vaguely suspect at 12V?
You made a point a week or two ago that the IRF510's require more drive to get significant power out?at 30mhz.?
That's fair enough.? The uBitx drivers to that final are built on $0.03 2n3904's, I wouldn't expect great?
performance at 30mhz.? Those that really need 20W on 30mhz could do well to follow your lead with
the RD16HHF1's.? Or they could add Fidel's 2 caps and inductor to get reasonably even output from the uBitx.
Maybe add a WA2EBY dual IRF510 amp to use with their uBitx and get Allison's 37W at 30mhz.
?
I'm coming down a bit hard here because I see absolutely no reason to alarm
several thousand forum readers with the prospect of a smoking crater where their rig used to be.
The IRF510's at 12v seem quite bulletproof, and an excellent choice for a $109 rig.
All that said, experimentation with other totally different finals is most welcome.
Jerry, KE7ER
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On Sun, Apr 29, 2018 at 08:21 am, K9HZ wrote:
¡°Exactly where did you find this data?¡±? Right here on the forum.? Multiple reports of IRF510 failures.? Not a single RD16HHF1 failure reported yet (now that doesn¡¯t mean it can¡¯t happen).? My own experience:? I unplugged the antenna at 20 watts while the transmitter was transmitting¡ it sat for several minutes while I took a phone call. It got hot but never failed.? I¡¯d love for someone to try that with the IRF510.? Bias is important only because there is no junction over-voltage protection.? So maybe there is a correlation between knowing how to replace the IRF device and not crank the bias pot up?
?
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Re: A steal for Arduino Experimenters
This is a board from eBay that I find very useful when trying out various projects using the Nano. Nano plugs in and there is access to every port pin and adjacent to each a 0V and 5V connection point. e  Bay search?? Nano I / O Expansion sensor Shield Module For Arduino UNO R3 Nano V3.0
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Re: Please don't make Radiuno with CH340/CH341 chipsets any more! Or at least advertise that you do use them!
#radiuno
If you find a Nano with an FTDI chip for $2, it's likely a clone FTDI chip.?
FTDI is fed up with supporting clones of their chips, have taken defensive measures.
As I recall, some of their drivers disable a clone chip that claims to be an FTDI.?
The genuine FTDI chips work very well, and are what's used on the original Arduino Nano.
This in a nutshell. While macOS may have issues with CH340 chips, Windows users tend to have issues with both FTDI and Prolific chips (in both cases, the market was flooded with cheap, cheerful and counterfeit PL2302s and FT232RLs and as a result Prolific and FTDI started locking out chips; even a lot of legit vendors were getting burned by this (most of the programming cables even offered by OEMs for Wouxun and Baofeng hand-helds turned out to be using counterfeit or at least blacklisted PL2032s, and Sparkfun actually got burned on a batch of FTDI chips that turned out to be counterfeit or at least blacklisted).? Apparently there are STILL issues to this day on Win7 and Win10 with the Prolific chips in particular... Probably the only chipsets that are a) legitimately inexpensive and b) work pretty much gracefully across all platforms seem to be the SiLabs CP2102 (which is honestly what I tend to use anymore with anything requiring a USB-to-serial connection--no issues with blacklisting, works pretty much out-of-the-box across OS's).? If the Raduino does end up redesigned, I'd humbly suggest using CP2102s :D -KI4QGJ
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By the way you have not stated witch BITX board you are testing. If it is a SMD version from Ashar Farahan
then you should do the carrier shifting mod suggested by VK3YE Peter Parker by witch you will move the carrier to place it correctly and improving the audio quality of the BITX. Replacing the carrier oscillator capacitor C102 with a lower value from 47pF to some thing like 22pF or 27pF and then again re aligning the carrier oscillator so achieve correct side band suppression? by tuning C103 This applies to almost all BITX boards and not uBITX Satish VU2SNK
On Sun, Apr 29, 2018 at 9:06 PM, Arv Evans <arvid.evans@...> wrote: Tim
Just disconnecting the microphone sometimes does not reduce incidental noise
in the audio spectrum enough for a good measurement of carrier balance.? This is
especially true if using a microphone preamplifier.? Shorting the microphone input
to ground kills any possibility of external AF, or external RF, getting into the audio
input and causing modulation.
It should be possible to do some minimal modification of the BFO balanced modulator
so you can have manual control of the balance.? This should not be necessary so you
probably want to do this in a non-destructive manner to allow restoration of the original
circuit if that does not solve the problem.?
Your situation is interesting.? It has been several years since I worked on the BITX20A
design, but there we always obtained at least 45 db of carrier suppression, and sometimes
in the range of 50 to 65 db.? This was with 1N4148 diodes which are supposed to be
inferior to those in the BITX-40 and uBITX.?
I think you have already addressed possibility of hum or noise on the power supply, so
that is probably not the problem.?
Arv
_._
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Tim
Just disconnecting the microphone sometimes does not reduce incidental noise
in the audio spectrum enough for a good measurement of carrier balance.? This is
especially true if using a microphone preamplifier.? Shorting the microphone input
to ground kills any possibility of external AF, or external RF, getting into the audio
input and causing modulation.
It should be possible to do some minimal modification of the BFO balanced modulator
so you can have manual control of the balance.? This should not be necessary so you
probably want to do this in a non-destructive manner to allow restoration of the original
circuit if that does not solve the problem.?
Your situation is interesting.? It has been several years since I worked on the BITX20A
design, but there we always obtained at least 45 db of carrier suppression, and sometimes
in the range of 50 to 65 db.? This was with 1N4148 diodes which are supposed to be
inferior to those in the BITX-40 and uBITX.?
I think you have already addressed possibility of hum or noise on the power supply, so
that is probably not the problem.?
Arv
_._
On Sun, Apr 29, 2018 at 8:37 AM, Tim Gorman <tgorman2@...> wrote: Arv,
I get the same carrier level in the spectrum analyzer with a tone or
without a tone, just the two-tone generator output impedance as a
termination.
When you say to terminate the mike input what impedance are you
thinking of? I've attached a png of the output circuit of the two-tone.
I use the line output which basically offers a 33K impedance to the mic
input.
I don't think it is the diodes themselves. If one or both of them were
bad I wouldn't expect even 25db of suppression.
I've never been a big fan of this kind of balanced modulator. There
isn't much you can do to maximize carrier balance.? I thought perhaps
it might be unequal inter-winding capacitance in T7 so I did the
best I could to equally space all the windings around the toroid and
the wire length to the circuit board but it made no difference at all.
I haven't tried yet but I've thought about lifting C63 to isolate the
mic pre-amp to see if that makes the carrier suppression better. I've
got everything torn down now to move the circuit board closer to the
back so I can use the box as a heat sink. When I get it all back
together I will try liftin C63 to see what happens.
tim ab0wr
On Sat, 28 Apr 2018 17:10:53 -0600
"Arv Evans" <arvid.evans@...> wrote:
> Tim
>
> Interesting.? How much carrier suppression do you get without tone
> insertion?
> Just terminate the mike input and balance the modulator without any
> modulation
> being inserted.? If that dip is too shallow then it could point to the
> modulator diodes
> themselves.
>
> Arv
> _._
>
>
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Re: ND6T AGC implementation for uBIT-X
¡°Exactly where did you find this data?¡±? Right here on the forum.? Multiple reports of IRF510 failures.? Not a single RD16HHF1 failure reported yet (now that doesn¡¯t mean it can¡¯t happen).? My own experience:? I unplugged the antenna at 20 watts while the transmitter was transmitting¡ it sat for several minutes while I took a phone call. It got hot but never failed.? I¡¯d love for someone to try that with the IRF510.? Bias is important only because there is no junction over-voltage protection.? So maybe there is a correlation between knowing how to replace the IRF device and not crank the bias pot up? ? ? Dr. William J. Schmidt - K9HZ J68HZ 8P6HK ZF2HZ PJ4/K9HZ VP5/K9HZ PJ2/K9HZ ? Owner - Operator Big Signal Ranch ¨C K9ZC Staunton, Illinois ? Owner ¨C Operator Villa Grand Piton ¨C J68HZ Soufriere, St. Lucia W.I. Rent it: Like us on Facebook! ? Moderator ¨C North American QRO Group at Groups.IO. ? email:? bill@... ? ?
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From: [email protected] [mailto:[email protected]] On Behalf Of Jerry Gaffke via Groups.Io
Sent: Sunday, April 29, 2018 6:16 AM
To: [email protected]
Subject: Re: [BITX20] ND6T AGC implementation for uBIT-X ? Exactly where did you find this data?
Most of the forum posts about dead IRF510's seem to be from people who twiddle bias pots for no particular reason.
A fuse or polyswitch in the PA-PWR line to the IRF510's would catch that before anything catastrophic,
and would be a good idea for the RD16HHF1's as well.
Other than that, I'd find it hard to imagine that a pair of IRF510's giving 5W each in a final on 12v would blow.
They are quite hardy even at 24v and 4x the power if you give them an adequate heat sink.
In post 22597, KB1GMX reports: My experience with IRF510s is extensive and much different. ?I rarely kill one even during experimenting.? I use them for RF power though 6M. ?How much 8 in a parallel 4x4 push-pull at 6M running 225W! ?My favorite is two in a push pull amp (K500r/wa2eby design) with 28V running about 55W on 40m and 37W at 10M and after 6 years of wrong antenna and all sorts of usual havoc its still running with the same pair.? Granted, the RD16HHF1 is 10x more expensive.?
So folks using the IRF510 might tend to be more "experimental" and blow one occasionally.
? ??
Yes, heat transfer from die to tab on the IRF510 is not ideal.
So if working it hard, be sure to give it an adequate heatsink.
Likewise the RD16HHF1 has a lower Vds max, so don't run it from supplies much over 12v.?
Jerry, KE7ER
On Sat, Apr 28, 2018 at 09:08 pm, K9HZ wrote: Well, data shows that the RD16HHF1 does have a lower ¡°kill rate¡± than the IRF510.? In fact, the RD16 device can run at higher power and still survive usual SWR problems (short, open, etc).? I don¡¯t think it has anything to do with voltage spikes, as the maximum voltage of the IRF510 is about double the RD16 device limits.? I have not studied the dies thoroughly, but I think it has to do with heat removal and the way the junctions are manufactured. ?
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Satish, No mic. Just the two-tone generator. When I get the rig put back together I'll try isolating the mic pre-amp to see if it is generating some kind of noise. It doesn't look like noise on the spectrum analyzer but I'm willing to try anything. tim ab0wr On Sun, 29 Apr 2018 20:14:39 +0530 "Satish Chandorkar" <satish.vu2snk1@...> wrote: Remove your microphone and then check for any carrier leakage at the
input of the crystal filter
and after the crystal filter. I do this with a RTL dongle. May be your
electrat mic may be faulty,
Just confirm. Happened with me.
Satish
VU2SNK
<>
Virus-free.
www.avast.com
<>
<#DAB4FAD8-2DD7-40BB-A1B8-4E2AA1F9FDF2>
On Sun, Apr 29, 2018 at 8:07 PM, Tim Gorman <tgorman2@...> wrote:
Arv,
I get the same carrier level in the spectrum analyzer with a tone or
without a tone, just the two-tone generator output impedance as a
termination.
When you say to terminate the mike input what impedance are you
thinking of? I've attached a png of the output circuit of the
two-tone. I use the line output which basically offers a 33K
impedance to the mic input.
I don't think it is the diodes themselves. If one or both of them
were bad I wouldn't expect even 25db of suppression.
I've never been a big fan of this kind of balanced modulator. There
isn't much you can do to maximize carrier balance. I thought
perhaps it might be unequal inter-winding capacitance in T7 so I
did the best I could to equally space all the windings around the
toroid and the wire length to the circuit board but it made no
difference at all.
I haven't tried yet but I've thought about lifting C63 to isolate
the mic pre-amp to see if that makes the carrier suppression
better. I've got everything torn down now to move the circuit board
closer to the back so I can use the box as a heat sink. When I get
it all back together I will try liftin C63 to see what happens.
tim ab0wr
On Sat, 28 Apr 2018 17:10:53 -0600
"Arv Evans" <arvid.evans@...> wrote:
Tim
Interesting. How much carrier suppression do you get without tone
insertion?
Just terminate the mike input and balance the modulator without
any modulation
being inserted. If that dip is too shallow then it could point
to the modulator diodes
themselves.
Arv
_._
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Re: Please don't make Radiuno with CH340/CH341 chipsets any more! Or at least advertise that you do use them!
#radiuno
Virtually any RasPi will do that, and most will run software equivalent or better than 'doze stuff for operation.
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Re: Diagnostic software for uBitx
#ubitx
Heathkit used to do this with some of its kits oh so many years ago. Then the concept seemed to disappear into the ether. Congrats to you for newly discovering the concept again. It is a concept that is of huge benefit to the newcomer to electronics that doesn't have the resources to build up a test bench right off. tim ab0wr On Sun, 29 Apr 2018 05:44:30 +0000 "Hans Summers" <hans.summers@...> wrote: Hi all
So far I have to say the Han's QCX concept is really
neat. It uses 6 passive components and provides an
on-board DC, AC/RF meter, RF power meter, frequency
meter and signal generator. Brilliant.
That coupled with the measuring functions pre-loaded
in software and an expected list of values seems the
best value for money in debugging a radio's circuit
and wiring. Thanks for the nice comments about the built-in test equipment and
alignment procedures in the QCX transceiver kit
! At the time I developed these features I
had no idea that they would create so much excitement.
I had never seen a kit with built-in test and alignment equipment
before. But I have personally in the past have built kits or
projects, and got all the way to the end - only to find what seems
like a very complex alignment procedure, or I need some other piece
of test equipment for it - and relegated the kit to the shelf for
seemingly infinite postponement.
The QCX concept was originally designed for the YOTA 2017 summercamp
buildathon hosted in UK by RSGB in August last year. I could imagine
a room full of youngsters finishing the assembly and getting stuck
for want of equipment to use for an adjustment procedure... or
fighting over one set of equipment the organizers had brought along
for the purpose. How much nicer, to have all the equipment built-in,
along with firmware assistance to guide you easily through the
process! In the QCX it's a Band Pass Filter peaking adjustment, then
the I-Q balance and phasing adjustment to get best unwanted sideband
suppression. It makes alignment simple. Literally just a few minutes
is all it takes to adjust it for around 60dB unwanted sideband
cancellation.
Once that far... It was a relatively small further thought step to
say, well why not add the DVM (which can later be jumpered to the
power supply input to allow an on-screen battery icon, useful for
portable use!), RF Power meter, frequency counter and signal
generator. It took very few additional components to add these, which
are useful if the assembly needs debugging, and even just for general
purpose use in the shack.
I'm really happy these built-in test and alignment equupment features
have turned out so popular!
73 Hans G0UPL
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K9HZ
Skip Davis
Satish Chandorkar