FY6800 Sig Generator as External VFO for Ten Tec Trasceivers? - Page 1
Forum section: electronics / rf-microwave

author: vinlove
author_rank: Frequent Contributor
timestamp: October 26, 2019, 08:49:14 pm
content: What is VFO? It just generates set RF signals, and feed into the IF Mixer of HF Radios?Would it mean that popular SG such as FY6800 modulation output of 5Mhz - 5.5Mhz AM into the Ten Tec Transeivers VFO input, and work as external VFO?I am not sure on the point that the FY6800 cannot generate SSB, but only AM or FM, but the Ten Tecs on;y operate on SSB. But then the Ten Tecs do have BFO, or ssb generating / converting modules to deal with the injected AM signals to ssb? I am not sure on these points. What do you guys think?

author: DimitriP
author_rank: Super Contributor
timestamp: October 26, 2019, 09:38:06 pm
content: VFOs are not modulated."All they have to do" is produce a clean, stable carrier.More importantly, which TenTec?

author: vinlove
author_rank: Frequent Contributor
timestamp: October 26, 2019, 09:43:14 pm
content: FY6800 has output for modulated am or fm sig.? So maybe it won't work as VFO? But they are still carrier? Be it modulated or not?The vintage Ten Tec Omni D.

author: radiolistener
author_rank: Super Contributor
timestamp: October 26, 2019, 10:36:56 pm
content: FY6800 has dirty signal for receivers. See for si5351, it has much more clean signal and better for receivers.

author: vinlove
author_rank: Frequent Contributor
timestamp: October 27, 2019, 07:51:36 am
content: I read that there are people who used old tube SGs for VFOs, and yes that would be real bad with dirty sig and drifts.But FY6800? It is a DDS based SG.

author: radiolistener
author_rank: Super Contributor
timestamp: October 27, 2019, 11:37:40 am
content: Quote from: vinlove on October 27, 2019, 07:51:36 amyes, this is DDS with low sampling rate (just 250 MHz) and this is why it has so dirty signal.For comparison, SDG2042 also DDS, but it uses 1200 MHz sampling rate but still bad for receivers. SDG2042 with it's 1200 MHz sampling rate has SFDR about 60 dB.Now you can imagine how bad FY6800 with it's 250 MHz. FY6800 has SFDR just 40 dB or even worse. This is very bad for receivers.For good receiver you're needs to use oscillator with ultra-low phase noise/jitter. DDS generators very noisy for receivers. But you can still use it for a low-grade receivers with terrible dynamic range, with a lot of spurs and images

author: radiolistener
author_rank: Super Contributor
timestamp: October 27, 2019, 11:40:45 am
content: Quote from: vinlove on October 27, 2019, 07:51:36 amold tube VFO may be not so stable, they have drift, but they have much more clean signal than cheap DDS like FY6800.

author: vinlove
author_rank: Frequent Contributor
timestamp: October 27, 2019, 05:37:16 pm
content: yeah, doesn't have to be modulated carrier, but even just sine or square carrier injection into the transceiver might work.I have seen many other DDS VFO / SGs a lot cheaper than the FY6800 working well as VFO.For example, AD9850 is about 10 usd from eBay, and it works very well for either SG or VFO.

author: vinlove
author_rank: Frequent Contributor
timestamp: October 27, 2019, 06:04:31 pm
content: That's not bad from 10 USD DDS VFO driving 7Mhz Radio.

author: radiolistener
author_rank: Super Contributor
timestamp: October 28, 2019, 07:56:45 pm
content: Quote from: vinlove on October 27, 2019, 05:37:16 pmany oscillator can be used for receiver. But it doesn't means that receiver will works good with dirty oscillator. Dirty oscillator leads to image reception and a lot of spurs (whistles at some frequencies).If it's okay for you to listen some station through whistles and image reception from different frequencies, you can use dirty oscillator.But if you want clean listening with high sensitivity, dirty oscillator is a wrong choice.

author: vinlove
author_rank: Frequent Contributor
timestamp: October 28, 2019, 10:24:27 pm
content: I just hooked up my FY6800 as an external VFO for my TenTec Omni D, and it is working treat. Rock solid digital reception with clean and quiet reception.I thought the OmniD turned into TS-990 or something like that, awesome.

author: vinlove
author_rank: Frequent Contributor
timestamp: October 28, 2019, 10:28:23 pm
content: I built a DDS VFO from kit too, and it works equally well as the FY6800.

author: vinlove
author_rank: Frequent Contributor
timestamp: October 29, 2019, 08:39:30 am
content: FY6800 driving the TenTec Omni D as external VFO. Sounds good.https://youtu.be/duYhNxrTvzMhttps://youtu.be/dERSKvrdIjk

author: vinlove
author_rank: Frequent Contributor
timestamp: November 01, 2019, 08:14:51 am
content: I did comparative tests with other DDS VFOs, but the FY6800 as HF VFO was not any inferior to any other VFO.In fact, it worked very well, and is very flexible in freq. steps change, and it even tunes on other bands, the transeciver originally does not have.

author: radiolistener
author_rank: Super Contributor
timestamp: November 01, 2019, 08:34:54 am
content: are you working on feeltech and your task is to advertise FY6800 on forums?

author: vinlove
author_rank: Frequent Contributor
timestamp: November 01, 2019, 11:59:39 am
content: Of course I don't have anything to do with FeelTech, apart from I own a FY6800.I am just surprised how well the FY6800 works with HF transceiver as VFO, especially when you said that it is dirty DDS, and will have lots of birdies and DDS noise, which was not true.In fact, many things you wrote in this forum were not trueI noticed.Just re-confirmed that with real testings with the devices.

author: radiolistener
author_rank: Super Contributor
timestamp: November 02, 2019, 03:22:22 am
content: Quote from: vinlove on November 01, 2019, 11:59:39 amCheap PLL on si5351 from aliexpress for 3 USD will works much better. Already confirmed by many peoples who using it as LO synthesizer for hand made receivers.Quote from: vinlove on November 01, 2019, 11:59:39 amI assumed that you understand what is dynamic range of receiver, what is sensitivity and how LO phase noise and spurs affects radio receiver performance. But it seems that you don't know nothing about it and receiver performance doesn't matter for you. You're just don't understand what I said.For example, here is an article which explains more details about things "which was not true" in your opinion:http://www.rfcafe.com/references/articles/wj-tech-notes/effect-LO-phase-noise-receiver-sensitivity-v8-6.pdfQuoteFrom my point of view, you're just trolling. Because I cannot believe that ham radio amateur don't understand so simple things. I cannot believe that ham radio amateur don't know about common mode currents on the antenna feeder (from your topic about PSU) and confusing mains ground with antenna ground.And I'm suspect you're clone of one user who flooded another topic with useless messages containing flood and advertisement about FY6800...

author: vinlove
author_rank: Frequent Contributor
timestamp: November 02, 2019, 08:54:40 am
content: You tinker with some google search papers, and think you know everything, and judge others as you like and feel is not right or fair.I read about the CMC like you did maybe well before and many more times, but still leave open minded when a problem is noticed, and put it for discussions and opinions, unlike you who imagine and conclude as you feel and like.I think this thread is useful tip for someone who is needing a VFO for quick test or set up for his HF radio project, or someone who want to make use of this FY6800 DDS SG as a VFO when it is doing nothing instead of buying one. I didn't know the FY6800 could be used as external VFO with good results, and could have actually bought a commercially made one. I am glad that I found out, and actually using the FY6800 as a spare VFO for my HF radios.Of course you don't see this point, and just brand all positive things as advertisement, because you yourself are commercially minded perhaps. Wake up, and see further away into the truths.

author: vinlove
author_rank: Frequent Contributor
timestamp: November 02, 2019, 09:04:45 am
content: double msg - deleted.

author: vinlove
author_rank: Frequent Contributor
timestamp: November 02, 2019, 09:52:41 am
content: Quote from: radiolistener on November 02, 2019, 03:22:22 amBy the way, talking about the PSU thread, you were wrong there too. You said that my antenna was broken and my transceiver will burn soon, but my transceiver is still working fine. And the shop that sold the old PSU has accepted it back and gave me full refund. It was the fault with the PSU.Since then I bought a new PSU, and it works perfect. Everything is working perfect with the new PSU. You seem to give out wrong answers to the problems, but still I never told you that you don't know anything. Because you are entitled to have you own opinion, and I respect that.You are also like some people on the net, that if they don't like or agree with someone, then brand them all as trolling. To me, that is not cool mate.

author: m3vuv
author_rank: Super Contributor
timestamp: November 06, 2019, 03:47:22 am
content: i remember reading the thread about your psu,im sure i commented,seemed one prat got it in his head it was your antenna and a few more thick twats went along with it,there realy are some know all A holes on this forum!!

author: radiolistener
author_rank: Super Contributor
timestamp: November 07, 2019, 03:21:58 am
content: That's all what you needs to know, about FY6800 as LO for receiver.For comparison, here is cheap (just 3 usd) si5351 generator:

author: vinlove
author_rank: Frequent Contributor
timestamp: November 14, 2019, 12:10:57 pm
content: radiolistener, you are missing the point of this thread. The OP was to trying to find how VFO in HF radios work, and if using a FG or SG like the FY6800 as VFO will work for the HF radios.It was not to compare different VFOs, or trying to find what VFO is the best.Of course the FY6800 is not produced to work as dedicated VFOs by its design. It is a counter, SG and FG, but it works as VFO too.You could write better posts in the forums, if you read the OP carefully, and trying to find out what the central point is before your posting, rather than jumping in and jump up and down with this is better and the best, and the others and the rest are rubbish, that type of posts, then fall back to advertising and troll accusation to others when your points were not taken in.

author: radiolistener
author_rank: Super Contributor
timestamp: November 14, 2019, 12:48:48 pm
content: Quote from: vinlove on November 14, 2019, 12:10:57 pmany generator which works at required frequency can be used as LO. This is not a unique property of FY6800, this is a property of generator in general. Why you're talking in such way like this is unique property of FY6800? There are a lot of less expensive and more useful solutions for LO.There are a lot of aggressive and annoying advertisement of FY6800 and your topic looks like yet another "Hey guys, here is cool FY6800, let's buy it" thread. Sorry, if you're not F***tech personnel, but it looks in such way