959 VFO windup question...

[Hawkeye351]

Hi all,
Got a 959 on the desk. The owner wanted a VFO windup installed, so I used a 1000uf 25v electrolytic cap. I tied the negative lead to board ground (not chassis) and the positive lead to the flapper pin of the tx frequency adjustment (VR).

This radio has a stock clarifier (will not slide on xmit, only receive). Aligned great and dead on frequency.

The question I have is, is the vfo windup suppose to increase your frequency when it settles?

Reason I ask is because when the windup is turned off, the xmit frequency is dead on, but when you turn it on then the xmit frequency stops at 500 hz high.

Example:
Switch off (solid 27.205)
Switch on (starts at 27.2000 and settles at 27.2055)

Got a 2547 with a stock clarifier someone else wants a VFO windup in it too.

Got a 2000 someone is wanting one in.
(Gotta put clarifier back stock first).

Got a friend wanting one in a 55v also, not sure if I can do this one or not.

Any tips on this issue with the 959 and VFO windup I could try?

 

[brandon7861]

The capacitor might be leaky, try reforming it for a while to decrease the leakage.
If you apply a leakage resistance across the TX adjust wiper, it decreases the voltage which will in turn increase the capacitance of the varactor and decrease the oscillator frequency. A decrease in frequency here will result in an increase [decrease] in VFO frequency to compensate so the loop mix (PLL input) frequency remains constant. You are seeing the [opposite] expected result of pulling the wiper voltage down a little.

If reforming the cap doesn't work, you might be able to use a trimmer to compensate for the difference. A high value pot is in parallel with the top half of VR7 when windup is engaged allowing a separate adjustment for the windup endpoint (because you need to bring the wiper voltage up a little when the leaky cap pulls it down). Nevermind

 

[nomadradio]

then the xmit frequency stops at 500 hz high.

Just seems backwards. A leaky capacitor is a resistor to ground. It should reduce the tuning voltage when it's switched into the circuit. Frequency follows voltage on this radio. Higher voltage is higher frequency. A leaky cap should have the opposite influence reducing tuning voltage and dropping the frequency.

I have no idea why that capacitor should drive transmit frequency up, not down.

73

 

[brandon7861]

I just realized my error too, the vco would follow the mix freq down. Not sure why i thought that

 

[Hawkeye351]

A local friend of mine paid around 1700 bucks for a Stryker 955. He said the tech decked it out with hifi xmit/receive (this info is freely available online), compressor board, echo module, xmit and receive upgrades and VFO windup.

Hmmm, from what I see, compressor boards aren't that expensive and not hard to install.
The Hi-Fi mod info is freely available and not hard to do.
The vfo windup is cheap and easy.
Echo modules aren't expensive and they're easy to install.
The xmit power mods doesn't show any better on signal than my other locals running my radios.

1700 bucks for a 10/11/12 meter radio?

I told this local he just got taken by a big name businessman whose soul purpose is making money, not being honest.

He told me the tech told him it takes a lot to get a VFO windup to work and I may not be able to do it. I told him to continue listening to his "Tech", lol...

He also said his big name tech told him he can't give out the "SECRET FORMULA" for nullifying coax because it's complicated to do, lol...omg... I told him of course a businessman in the business of making money isn't gonna give out the "SECRET CODE" which makes him money. I told him there is no secret code, I told him if he's interested then it's 492/freq in mhz × of of coax for electrical half wavelength and 246/freq in mhz × vf for electrical quarter wavelength. I told him it's best to use an analyzer if you're into the nulling coax thing but it's no secret.

Money, money, money.... 1700 bucks for a CB radio, omg... That's about as retarded as spending 2 thousand on a cobra 2000.

Takeaway:
Some do it for money, others do it to help others. We all do things differently, but please stop taking advantage of people. These operators have been taken advantage of and ripped off for far too long, they're not stupid so stop treating them as such just to fatten up that wallet.

 

[SuperLid]

A local friend of mine paid around 1700 bucks for a Stryker 955. He said the tech decked it out with hifi xmit/receive (this info is freely available online), compressor board, echo module, xmit and receive upgrades and VFO windup.

Hmmm, from what I see, compressor boards aren't that expensive and not hard to install.
The Hi-Fi mod info is freely available and not hard to do.
The vfo windup is cheap and easy.
Echo modules aren't expensive and they're easy to install.
The xmit power mods doesn't show any better on signal than my other locals running my radios.

1700 bucks for a 10/11/12 meter radio?

I told this local he just got taken by a big name businessman whose soul purpose is making money, not being honest.

He told me the tech told him it takes a lot to get a VFO windup to work and I may not be able to do it. I told him to continue listening to his "Tech", lol...

He also said his big name tech told him he can't give out the "SECRET FORMULA" for nullifying coax because it's complicated to do, lol...omg... I told him of course a businessman in the business of making money isn't gonna give out the "SECRET CODE" which makes him money. I told him there is no secret code, I told him if he's interested then it's 492/freq in mhz × of of coax for electrical half wavelength and 246/freq in mhz × vf for electrical quarter wavelength. I told him it's best to use an analyzer if you're into the nulling coax thing but it's no secret.

Money, money, money.... 1700 bucks for a CB radio, omg... That's about as retarded as spending 2 thousand on a cobra 2000.

Takeaway:
Some do it for money, others do it to help others. We all do things differently, but please stop taking advantage of people. These operators have been taken advantage of and ripped off for far too long, they're not stupid so stop treating them as such just to fatten up that wallet.

There's super tech's and there's stupid techs. Then there is no shortage of suckers either.

 

[Hawkeye351]

I've also noticed the receive frequency is affected when the vfo windup switch is flipped on. I then have to turn the clarifier to around 3 o'clock to tune people in on SSB, but when the switch is off everyone is basically at 12 o'clock on the clarifier. This clarifier is stock, all parts in the clarifier section correspond to the schematic and only the receive frequency shifts when rotating the clarifier, transmit isn't affected.

Tried another cap, same results. I'm using Nichicon 1000uf 25v electrolytic caps.

The switch is in the back of the radio (back wall beside so239 input). The positive lead of the cap is soldered to the center pin of the spst switch. The top pin of the switch has a wire soldered to it which leads to the flapper (center) pin of the xmit frequency adjustment on the front edge of the board. The negative lead of the cap has a wire soldered to it which leads to a ground tap on one of the oscillator cans near the xmit frequency adjustment.

Could the wires be too long, or affecting nearby circuits by bleeding off through the wires insulation? Is there a better ground location for the negative lead of the cap I should try? Maybe a different brand of caps?

Gonna fiddle around with it a little more. The owner doesn't use SSB and it doesn't go off much, I got it adjusted now so it's only off by 200 to 300 hz, but still off.

 

[Cable Guy]

Brandon's post shows another VR connected to the cap, which keeps the cap in circuit always, just not switched onto the "flapper" lol. Sorry, that's funny to me. It sounds like you are just switching a cap in and out. Maybe connect as Brandon's post shows, tune for freq with switch off, then see.


I think what I'm getting at is the cap is always connected from ground to above vr7 thru its own VR. Maybe without that connection, you can't tune for the effects of the cap when unswitched. I could be wrong, but that line connects to a varactor diode, which uses voltage to adjust capacitance, and tuning the can without that capacitor already exerting its effects on the varactor, just switching it in could cause goofy issues, but again, I could be wrong just offering my 2 cents. Glad to see you out and about again.

 

[BayouRadioAmplifier]

this is new to me. what is this "VFO windup" circuit about? ?

causing your frequency to sweep. what is the application?

on one radio I disconnected what appeared to be a faulty
roger beep board. I was told it was working normally,
and put it back in circuit. I was told it is a "duck fart" board.

then I came across amplitude modulation problems on RCI/Galaxy
radios, due to a diode, and maybe also a resistor, as a "NPC mod"

 

[Hawkeye351]

 

[Hawkeye351]

So, if I got this right,


I take a separate variable resistor and tie the flapper of said VR to the positive lead of the electrolytic cap. I then solder solder those two together to the center pin of the spst switch. I then take a wire and solder to the unused pin of the spst and run the other end to the flapper of VR 7 (radios stock xmit frequency adjustment). I then take a separate wire and solder to the low end tab of the added variable resistor (one end stays floating) and run the other end of this wire goes to the high end tab of the stock VR7 frequency adjustment. I then take a separate wire and solder one end to the negative of the electrolytic cap and the other end to ground side of R197. Then align the factory VR7 with switch off, then adjust the new added VR with switch on.

Is this correct? That's what I take from the diagram.

 

[Cable Guy]

Per the diagram, yes, try that and see. I have never don't a vfo wind-up before, never saw the need.

 

[Hawkeye351]

I have no desire for it neither, but these locals are asking for it, so it's something I need to read up on and learn from so I can see if I can accomplish this for them.

 

[Hawkeye351]

What should the value of the added variable resistor be? Same value as the radios stock xmit frequency adjustment variable resistor? I'm assuming the same value.

 

[Cable Guy]

I don't know where Brandon got the added VR info from, according to other sources just a cap and switch for the 959. Which board is in it? I thought most Galaxy radios wouldn't take the vfo mod anyways.

Ah, reading the crossed out text says it's to maybe fix a leaking cap