Hello everyone, everything good ? I have a problem with installing the FC390 frequency meter on my 148GTL snake. I did the installation of the frequency meter according to the scheme, I did not use any capacitor in the VCO cable, I did some capacitor tests of 47pf / 39pf / 68pf / 100pf / and all above channel 80 showed the wrong frequency, at 78.xxx MHz , when I used a 103pf it made the correct reading and when I use without capcitor it also makes the correct reading in RX. However in TX above channel 70 the frequency meter makes a totally misleading reading and oscillating, it does not remain stable, in tx it oscillates. Could someone tell me what it could be? THANKFUL
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Adding Frequency Counter to Cobra 148 GTL with front panel mic.
- Thread starter 8113 Northern MN
- Start date
if someone has the correct picture of the installation and information about the reason why the frequency converter oscillates the frequency reading in TX (transmission) please send to rciato@outlook.com
it sounds like your VCO is going out of lock on the high channels and causing the freq counter to go erratic.
try adjusting your VCO coil to where it will lock on the high channels.
you may now lose some low channels.
going back and forth with the VCO adjustment will show you what the actual range of the VCO lock is.
The VCO in the 148GTL is L19.
LC
try adjusting your VCO coil to where it will lock on the high channels.
you may now lose some low channels.
going back and forth with the VCO adjustment will show you what the actual range of the VCO lock is.
The VCO in the 148GTL is L19.
LC
Does the FC 347 schematic work with the FC-390 - I see something in the 347 that is creepy, and need to clarify - because the problem he is having can be related to it.
I guess I was more concerned about the amp design. because with both, you can have a attenuation as well as out of lock issue depending on how the "tap" and where the tap was placed and how the part you tapped from is oriented...
Rev. C board, the 10K is ACROSS the lead-in to the box ground.
Rev D board, the 10K is STILL ACROSS the Lead-in to the box ground.
In Rev C - the grounds are tied even at the Lead-in.
In Rev D/ - the grounds are NOT equal - only RF provided - DC is blocked - at the Lead-in.
Depending on how the tap is made, if you use the COMPONENT side of the board for the tap lead-in - you use the parts in a way that the signal is tapped but not attenuated. You get one result.
If you tap from the FOIL side - as I have seen - you get an unstable result - DUE TO PARALLEL CAPACITANCE - as in what he's taking about - DIRECTLY - you couple to the counters' Buffer amp thru C14 in D and C13 in C...anyone else noticing the 10K 's location and quality of the amps' ability to amplify?
Hint - where's' R2 - per R1 and R2 (divider) or R10/R11 or R13/R11 and R12 - electrically DC isolated from Base to Ground at that buffer amp affecting Class as well as its' ability to be linear...
Anyone?
I guess I was more concerned about the amp design. because with both, you can have a attenuation as well as out of lock issue depending on how the "tap" and where the tap was placed and how the part you tapped from is oriented...
Rev. C board, the 10K is ACROSS the lead-in to the box ground.
Rev D board, the 10K is STILL ACROSS the Lead-in to the box ground.
In Rev C - the grounds are tied even at the Lead-in.
In Rev D/ - the grounds are NOT equal - only RF provided - DC is blocked - at the Lead-in.
Depending on how the tap is made, if you use the COMPONENT side of the board for the tap lead-in - you use the parts in a way that the signal is tapped but not attenuated. You get one result.
If you tap from the FOIL side - as I have seen - you get an unstable result - DUE TO PARALLEL CAPACITANCE - as in what he's taking about - DIRECTLY - you couple to the counters' Buffer amp thru C14 in D and C13 in C...anyone else noticing the 10K 's location and quality of the amps' ability to amplify?
Hint - where's' R2 - per R1 and R2 (divider) or R10/R11 or R13/R11 and R12 - electrically DC isolated from Base to Ground at that buffer amp affecting Class as well as its' ability to be linear...
Anyone?
The 14D schematic looks as if it could work by just tapping into the radio's VCO output, where it splits off to the receiver and transmitter mixers. The input impedance should be 1000 ohms or more, too high to disrupt the radio you tap into.
But the older one reflects a design feature of all the Galaxy radios, both the 40-channel and "10-meter" models. Those radios each have a separate buffer-amplifier circuit that serves only to drive the counter input. It isolates any loading caused by a counter input to be isolated from the radio's transmit and receive circuits.
No doubt the input circuit in the 14C version would tend to load down the circuit you tap it into. A Galaxy radio won't care, it's built for this. Has plenty of drive into the counter's input.
But simply tapping off the test point in a radio not built for this gets trickier. If you put a resistor (usually 100 ohms or more) in line with the center wire of the counter's input coax, you might not get enough drive to the counter. The digits just jiggle around when this happens.
But connecting it direct to the test point could pull down the transmit power and receiver sensitivity. We have found 100 ohms usually prevents crippling the radio.
Never really compared these two before.
Thanks, Andy.
73
But the older one reflects a design feature of all the Galaxy radios, both the 40-channel and "10-meter" models. Those radios each have a separate buffer-amplifier circuit that serves only to drive the counter input. It isolates any loading caused by a counter input to be isolated from the radio's transmit and receive circuits.
No doubt the input circuit in the 14C version would tend to load down the circuit you tap it into. A Galaxy radio won't care, it's built for this. Has plenty of drive into the counter's input.
But simply tapping off the test point in a radio not built for this gets trickier. If you put a resistor (usually 100 ohms or more) in line with the center wire of the counter's input coax, you might not get enough drive to the counter. The digits just jiggle around when this happens.
But connecting it direct to the test point could pull down the transmit power and receiver sensitivity. We have found 100 ohms usually prevents crippling the radio.
Never really compared these two before.
Thanks, Andy.
73
Good morning guys .... after breaking my head a lot, I discovered the reason why my FC390 was doing the correct reading of my RX and my TX reading oscillating and totally wrong ...
Letting the chavemanto of my snake 148gtl is installed an expander chanel of 172+ and 16-, of 3 digits
It was the cable of the frequency meter being passed over the equipment board, put it in a way that it went out on the side of my radio going through the inside of the radio and the problem is over ... In other words, it was stable. I noticed a slight variation of some hertz in tx in the frequency meter when it reaches a temperature of use, but nothing that dissapoints and even in channels above 110.
But I believe it is due to the switching that causes high channel variance.
Before switching the position cable I had carried out test with capacitors of all values 39pf / 47pf / 68pf / 100pf and none did the correct reading in tx, above 50 channels it changed to 78.xxxMHz. only with a capacitor of 103pf did it read correctly. But even so, I connected the frequency cable to the card directly and the rx reading is accurate on all channels. I also tried to connect a 100 ohm resistor and the rx reading was also wrong in the 78.xxx Mhz. The best option was direct soldering without capacitor and without resistor.
I believe there is a variation from one radio to another.
Anyway, I thank you immensely for the help of all of you, if you have any other suggestions you are always welcome.
A big hug in everyone.
Letting the chavemanto of my snake 148gtl is installed an expander chanel of 172+ and 16-, of 3 digits
It was the cable of the frequency meter being passed over the equipment board, put it in a way that it went out on the side of my radio going through the inside of the radio and the problem is over ... In other words, it was stable. I noticed a slight variation of some hertz in tx in the frequency meter when it reaches a temperature of use, but nothing that dissapoints and even in channels above 110.
But I believe it is due to the switching that causes high channel variance.
Before switching the position cable I had carried out test with capacitors of all values 39pf / 47pf / 68pf / 100pf and none did the correct reading in tx, above 50 channels it changed to 78.xxxMHz. only with a capacitor of 103pf did it read correctly. But even so, I connected the frequency cable to the card directly and the rx reading is accurate on all channels. I also tried to connect a 100 ohm resistor and the rx reading was also wrong in the 78.xxx Mhz. The best option was direct soldering without capacitor and without resistor.
I believe there is a variation from one radio to another.
Anyway, I thank you immensely for the help of all of you, if you have any other suggestions you are always welcome.
A big hug in everyone.
Whew, glad to know you got it working.
Routing the cable can make or break any install.
What I was researching was the amp used in the counter itself. Could we make it better for low-level signals that would otherwise not make the counter lock onto what was present back at the radio?
One of the many faults of frequency counters are their inability to discriminate against stray spurious signals that can interfere or generate a mixing product that is not your frequency but someone else's by your location - because of the leakage the counter picked up may be theirs not yours.
To reduce an attenuation issue, I just noticed the Schematic showed 10K ACROSS the input signal - not the coupling cap present (signal there first then resistor?). Why do it this way when you can use the coupling cap and then use the divider network BEHIND the cap - and you can then provide a method to "trim and amplify" the signal present on the cable at the transistor - else the signal trying to arrive is attenuated by the 10K resistor first, then appears at the cap. So why even do that?
That was what I saw, and unfortunately - life gets in the way so all I could show was the schematic and ask some "dumb questions" to answers I don't even know - Like its' ok for Vegans to Eat Animal Crackers - just eat the ones that eat veggies, like Bunnies and Mice - skip the Meat eaters like Lions Tigers and Bears...and putting mom to bed for the night...SIGH - lest we forget - "Oh My!"
Anyhoo, just noticed a quirk - don't panic, we're still here...
:+> Andy <+:
Routing the cable can make or break any install.
What I was researching was the amp used in the counter itself. Could we make it better for low-level signals that would otherwise not make the counter lock onto what was present back at the radio?
One of the many faults of frequency counters are their inability to discriminate against stray spurious signals that can interfere or generate a mixing product that is not your frequency but someone else's by your location - because of the leakage the counter picked up may be theirs not yours.
To reduce an attenuation issue, I just noticed the Schematic showed 10K ACROSS the input signal - not the coupling cap present (signal there first then resistor?). Why do it this way when you can use the coupling cap and then use the divider network BEHIND the cap - and you can then provide a method to "trim and amplify" the signal present on the cable at the transistor - else the signal trying to arrive is attenuated by the 10K resistor first, then appears at the cap. So why even do that?
That was what I saw, and unfortunately - life gets in the way so all I could show was the schematic and ask some "dumb questions" to answers I don't even know - Like its' ok for Vegans to Eat Animal Crackers - just eat the ones that eat veggies, like Bunnies and Mice - skip the Meat eaters like Lions Tigers and Bears...and putting mom to bed for the night...SIGH - lest we forget - "Oh My!"
Anyhoo, just noticed a quirk - don't panic, we're still here...
:+> Andy <+:
After a while with the radio turned on in high channels it again showed read variations in TX mode on the frequency meter.
When I soldered a resistor of 100 ohms in the cable welded to the board of the radio the readings even in rx were mistaken, is it that if you do as you mentioned to solder this resistor in the positive of the cable vco in the board of the equometer ends the problem?
Sorry for my ignorance, I'm not a technician.
I am very grateful for any kind of help and suggestions.
When I soldered a resistor of 100 ohms in the cable welded to the board of the radio the readings even in rx were mistaken, is it that if you do as you mentioned to solder this resistor in the positive of the cable vco in the board of the equometer ends the problem?
Sorry for my ignorance, I'm not a technician.
I am very grateful for any kind of help and suggestions.
No remove that part, the 100 ohms can make the problem worse - won't damage it per-se - but it can re-create the problem you're trying to fix.
Just go back to where you had it working.
Part of the problem is when you run a weaker signal output - the counter can't always track the frequency the radio is producing. It's a weak signal. Doesn't mean or indicate the radio is faulty - just the counter doesn't have a good quality signal to lock into so what the radio operates on, doesn't always mean it's off frequency, just not enough there to make the counter work. Else the radio itself will become unstable - you'd know it - because it won't lock in by itself.
The counter has an amp - that if properly set up - you should not be having such a problem like you have now, I'm trying to find a way to fix that, so that when others follow that same path, they can move forward using the steps, process and parts to develop a signal that is strong enough to make the counter work, and not generate a "SATURATION" or clipping issue skewing the results you're seeking because you now have that signal strong enough at the extreme ends to lock into - it's now a problem with the counters ability to track strong signals that are closer to the peaking region of the radio's IF your sampling - generating a dynamic headroom, clipping issue.
Just remember that the counter takes some of that RF energy away from the section, weakening it's own ability to maintain lock and feedback loop processing. I wish I had more ability to produce a solution - but at this time the only thing I can easily see if the limitation. By the symptoms and researching the schematic, they show several faults including an attenuation issue that is some ways is needed to TERMINATE the signal without too much reflection back into the tuning circuit it's trying to sample, but what you don't want is ATTENUATION - in a way it's an interference problem - just not sure if it's a "Standing wave" condition causing the interference and spurious wave problem - like poorly terminated cables tend to generate a noise loop screwing everything up because the branch reflects back to the splitter a signal that is either out of phase or noises at a level that injects more noise to mask what you are looking for.
There are two issues at play here...
The internal oscillator of the FC-390 and the internal oscillator of the radio. One is supposed to stay isolated from the other - so they too make noise and also have their own types of internal dampers - (or inertial SIC) so the signal used to generate the gate cycles for the window to count the SAMPLE - should not add their own "counts" to the window and not send a signal back to the system you want to sample. Hence your 78.xxxMHz default.
I'm just trying to bring a problem I've had before, to the forefront to either locate a fix, try and find a solution, just looking for ideas.
Just a peaceful discussion nothing more. I don't want a re-make of - that when brought up on another forum long ago, somehow got into twisted arguments with others over various quality issues that didn't produce anything but - posts... with a lot of nails...worse than Martin Luthers' 29 Thesis. Back then in the days where CRTs were the norm...
Anyways, don't mind me, I'm harmless - just looking for something that got lost a long time ago...
:+> Andy <+:
Just go back to where you had it working.
Part of the problem is when you run a weaker signal output - the counter can't always track the frequency the radio is producing. It's a weak signal. Doesn't mean or indicate the radio is faulty - just the counter doesn't have a good quality signal to lock into so what the radio operates on, doesn't always mean it's off frequency, just not enough there to make the counter work. Else the radio itself will become unstable - you'd know it - because it won't lock in by itself.
The counter has an amp - that if properly set up - you should not be having such a problem like you have now, I'm trying to find a way to fix that, so that when others follow that same path, they can move forward using the steps, process and parts to develop a signal that is strong enough to make the counter work, and not generate a "SATURATION" or clipping issue skewing the results you're seeking because you now have that signal strong enough at the extreme ends to lock into - it's now a problem with the counters ability to track strong signals that are closer to the peaking region of the radio's IF your sampling - generating a dynamic headroom, clipping issue.
Just remember that the counter takes some of that RF energy away from the section, weakening it's own ability to maintain lock and feedback loop processing. I wish I had more ability to produce a solution - but at this time the only thing I can easily see if the limitation. By the symptoms and researching the schematic, they show several faults including an attenuation issue that is some ways is needed to TERMINATE the signal without too much reflection back into the tuning circuit it's trying to sample, but what you don't want is ATTENUATION - in a way it's an interference problem - just not sure if it's a "Standing wave" condition causing the interference and spurious wave problem - like poorly terminated cables tend to generate a noise loop screwing everything up because the branch reflects back to the splitter a signal that is either out of phase or noises at a level that injects more noise to mask what you are looking for.
There are two issues at play here...
The internal oscillator of the FC-390 and the internal oscillator of the radio. One is supposed to stay isolated from the other - so they too make noise and also have their own types of internal dampers - (or inertial SIC) so the signal used to generate the gate cycles for the window to count the SAMPLE - should not add their own "counts" to the window and not send a signal back to the system you want to sample. Hence your 78.xxxMHz default.
I'm just trying to bring a problem I've had before, to the forefront to either locate a fix, try and find a solution, just looking for ideas.
Just a peaceful discussion nothing more. I don't want a re-make of - that when brought up on another forum long ago, somehow got into twisted arguments with others over various quality issues that didn't produce anything but - posts... with a lot of nails...worse than Martin Luthers' 29 Thesis. Back then in the days where CRTs were the norm...
Anyways, don't mind me, I'm harmless - just looking for something that got lost a long time ago...
:+> Andy <+:
Muito obrigado Andy ...
O amigo como sempre muito prestativo, agradeço muito pelo seu esclarecimento ...
Eu realmente percebi que, mesmo me perguntando se esse problema não está relacionado à troca de rádio. Porque isso só acontece em canais altos, então o rádio em canais altos está trabalhando fora de seu parâmetro normal correto ele é adaptado para trabalhar em frequências que não foram projetadas, então a variação de potência e pll não são normais.
Na verdade, a impressão é que o rádio não fornece energia suficiente ao FC390 para ler a freqüência correta em canais altos.
As minhas ovas são de 1.3 SWR, por isso os problemas relacionados com ovas são descartados.
Quando o equipamento é ligado, o conversor de freqüência lê corretamente ambos, tx e rx, mas depois de um certo tempo a unidade aquece lendo o fc390 no modo TX, ele oscila demais em canais altos acima de 70.
Meu switch é o expansor de canal que faz 172 canais positivos e 16 canais negativos e o dislay de canal de 3 dígitos, não sei se esse switch pode ser responsável pelo problema.
É muito legal essa troca de informações, isso é saudável ...
Talvez não tenhamos encontrado uma solução para isso ...
O amigo como sempre muito prestativo, agradeço muito pelo seu esclarecimento ...
Eu realmente percebi que, mesmo me perguntando se esse problema não está relacionado à troca de rádio. Porque isso só acontece em canais altos, então o rádio em canais altos está trabalhando fora de seu parâmetro normal correto ele é adaptado para trabalhar em frequências que não foram projetadas, então a variação de potência e pll não são normais.
Na verdade, a impressão é que o rádio não fornece energia suficiente ao FC390 para ler a freqüência correta em canais altos.
As minhas ovas são de 1.3 SWR, por isso os problemas relacionados com ovas são descartados.
Quando o equipamento é ligado, o conversor de freqüência lê corretamente ambos, tx e rx, mas depois de um certo tempo a unidade aquece lendo o fc390 no modo TX, ele oscila demais em canais altos acima de 70.
Meu switch é o expansor de canal que faz 172 canais positivos e 16 canais negativos e o dislay de canal de 3 dígitos, não sei se esse switch pode ser responsável pelo problema.
É muito legal essa troca de informações, isso é saudável ...
Talvez não tenhamos encontrado uma solução para isso ...
Again, thank you for starting a conversation.
We wish you the best in your endeavor - Yes, it's the high frequency roll-off issue and as with any tuned circuit - they are sensitive to any stray reactive components - even with the coax cable itself can attenuate the signal within a few feet of it's point of origin to a point where the signal is degraded and un-useable.
I hope to have a solution soon, or at least a picture of how you can possibly fix it.
Don't be a stranger! check in every now and then!
:+> Andy <+:
We wish you the best in your endeavor - Yes, it's the high frequency roll-off issue and as with any tuned circuit - they are sensitive to any stray reactive components - even with the coax cable itself can attenuate the signal within a few feet of it's point of origin to a point where the signal is degraded and un-useable.
I hope to have a solution soon, or at least a picture of how you can possibly fix it.
Don't be a stranger! check in every now and then!
:+> Andy <+:
Ok so here we go, all this info was very helpful. My friend was trying to hookup an fc347 with the board that ends in D. Soldering to the bottom of the board did not allow enough signal to drive the counter. So we soldered to the TP3 and boom it came right in. Problem now was the frequency counter reads 2.5khz low. So I saw a video on Youtube from Mike's Radio Repair that showed what to do in this situation. On this latest board, there is an empty slot right next to the trimmer capacitor, two empty pads. This is to add extra capacitance so you can adjust the the frequency. He used a 15pf cap and it worked perfect. We have a 15pf cap on order and I am sure this will take care of the problem. Just so people who come across this thread will have and answer. Also you have to sold both pads on the freq counter. Hope this all helps
Scott
w4ffx
192nc
Scott
w4ffx
192nc
Please forgive me for resurrecting this year old thread, I do it because it is the same topic; the Fc347 frequency counter. I am NOT a tech in anyway shape or form. I am having a problem wiring it into my Grant XL, & having it work properly. I have followed the picture that Sonoma posted. So far, when I power up the radio & frequency counter it reads 76.0830, it stays like that no matter what channel the radio is on. The only time I can get it to change is when I go to LSB or USB. Then it reads 76.0850 & 76.0820 respectively. I have installed a 100pf cap inline on the white wire for the VCO & there has been no change from without it. I am hoping that one of the brilliant minds here will be able to save my bacon as I am starting to go sane...
Thank you in advance.
Thank you in advance.
Ok, so you know, looks like you've tapped the wrong IF Point.
Your "Shift" which is programmed in automatically to redisplay the offset for USB or LSB is ok, leave that wiring alone...
What TP point did you use?
Your "Shift" which is programmed in automatically to redisplay the offset for USB or LSB is ok, leave that wiring alone...
What TP point did you use?