Good and not-so-expensive AM/FM Signal generator ABO AVR-5500-PI - Page 1
Forum section: electronics / testgear

author: RiRaRi
author_rank: Regular Contributor
timestamp: October 19, 2023, 10:26:52 pm
content: I want to buy RF signal generator for aligning FM and AM radio and was looking at Siglent frequency generator (120mhz) but as far as i can see i can not transmit only left or right side for aligning and checking stereo receiver devices. But i like Siglent ones because of low noise and every other function that i may or may not need. But also i came across this Ebay ABO AVR-5500-PI device which can not produce other then sine wave but could be great device for aligning receivers. I am new to this "advanced" field in servicing radios so i need advice. I need pros and cons with using Siglent 1000dollar and this 390dollar devices only in terms of servicing radio receivers, amplifiers and similar devices. Right now i only use ESR meter, good linear PSU, good transistor tester and DMM. But i am planning to learn more and get digital two channel scope, sig gen and isolation transformer. I can also buy scope with built-in freq gen. What would you reccomend and do i maybe need both.https://www.ebay.com/itm/364169543139?mkcid=16&mkevt=1&mkrid=711-127632-2357-0&ssspo=OBJrC5xMT6a&sssrc=4429486&ssuid=w8s-0nahtem&var=&widget_ver=artemis&media=COPY

author: TimFox
author_rank: Super Contributor
timestamp: October 19, 2023, 11:29:01 pm
content: Many, many years ago, Heathkit had an FM generator with vacuum tubes that included stereo encoding.There are boatanchors from the time of the introduction of stereo multiplex, and expensive units (maybe no longer available) from the solid-state era.When I wanted to generate a suitable FM-stereo signal, I bought an interesting circuit board from a company that sells equipment to low-power FM broadcasters, and connected it into the external modulation signal input of a good RF generator with FM capability.The board was the "Veronica" from AAREFF: I don't know if it is still available.https://www.aareff.com/en/fm-transmitter-stereo-coder-kit/Its output is the equivalent of the output from an FM demodulator inside an FM receiver.The board comes pre-wired (with cheaper components than I like), but requires an external +/- 15 V DC supply.You will need to take care about the signal levels with respect to the "external modulation" input levels of whichever RF generator you use.The "left" and "right" sides result from applying an audio signal (e.g., 1 kHz) to input "A" or input "B" of the "Veronica" board, to generate a "baseband" signal suitable for frequency-modulating the RF generator's carrier.The generator is one of my boatanchors: Wavetek 2405, a synthesized 500 MHz generator with AM and FM modulation capability from eBay that needed re-calibration.(Side comment: please use correct spellings of "MHz", etc. The "mHz" does exist, but is far from what you intend to say.)

author: coromonadalix
author_rank: Super Contributor
timestamp: October 20, 2023, 02:44:27 am
content: this generator would be good for any am fm receivers, and help you tune I/F coils / circuits of old stuffi would avoid having / buying scope with arb gen / sig gen like Hantek, sure it could be helpful and have a low cost .. i had the highest model with gen and was not impressedi think you could invest in a slightly more capable brand ie like Siglent who can be upgraded cough cough loll for free, just ned appopriate probes after the "upgrade"Having both Rigol and Siglent, i vouch more for the Siglent, lots of infos, and downloads like visa stuff, labview examples etc ... more "better" experience if i may sayi have thoses little Junctek jds2900 series generators, simple cheap and efficient without paying lots of cash, unless you require absolute precision

author: DaneLaw
author_rank: Frequent Contributor
timestamp: October 20, 2023, 03:28:41 am
content: Deja vu, why not continue all your previous threads about the same topic?"Signal gen for radio tuning AM/FM ??" you previously excused yourself for thread-humping, and you would continue your previous threads, with the same topic.// fxhttps://www.eevblog.com/forum/testgear/budget-rf-audio-generator-options-for-tuning-radio-receivers/https://www.eevblog.com/forum/testgear/budget-signal-generator-for-aligning-am-and-fm-radio-and-what-else-do-i-need/https://www.eevblog.com/forum/beginners/is-scope-and-freq-generator-needed-for-repair-vtg-solid-state-audio-gear/OP, you are allowed to edit, your older threads, like the headline if you wanna incl. a certain product.

author: coromonadalix
author_rank: Super Contributor
timestamp: October 20, 2023, 10:13:47 am
content: oh ho bad boy baaaad loll

author: RiRaRi
author_rank: Regular Contributor
timestamp: October 20, 2023, 10:36:19 am
content: Thanks everyone. Sorry about the new thread but as i found new test equipment i made new thread. So yes, this ebay device will give me sine wave and could align coils and the radio. But are there any other things when fixing a radio where i could need another freq generator then this ebay device? Maybe some with smaller freq range for testing components and the one that could produce multiple waveforms?

author: DaneLaw
author_rank: Frequent Contributor
timestamp: October 20, 2023, 03:45:18 pm
content: Quote from: RiRaRi on October 20, 2023, 10:36:19 amYou don't read what people are writing to you? you asked the same question in all the other threads, - it's like it simply doesn't resonate with you.people have recommended anything under the sun for your criteria, also with links.Maybe, go through all the replies you got, are there any specific reasons why those recommended options won't do..?https://www.eevblog.com/forum/testgear/budget-rf-audio-generator-options-for-tuning-radio-receivers/https://www.eevblog.com/forum/testgear/budget-signal-generator-for-aligning-am-and-fm-radio-and-what-else-do-i-need/https://www.eevblog.com/forum/beginners/is-scope-and-freq-generator-needed-for-repair-vtg-solid-state-audio-gear/

author: tv84
author_rank: Super Contributor
timestamp: October 20, 2023, 04:12:48 pm
content: I bet he'll answer you by opening a new thread...

author: RiRaRi
author_rank: Regular Contributor
timestamp: October 20, 2023, 09:11:40 pm
content: Hahah i will not. The problem is they reccomend 1000 dollar ones which as i can see can not transmit in stereo, left and right channel separately as they are freq gen and not devices specifily made for aligning receivers. So i was thinking to buy this ebay one and maybe another cheaper one from Siglent 10MHz or something like that which are less expensive for test components etc. So my question is which device or devices would you reccomend for these jobs of servicing radio receivers, amps and similar devices

author: TimFox
author_rank: Super Contributor
timestamp: October 20, 2023, 09:13:58 pm
content: If you really need L & R channel for multiplexed stereo, you can try my suggestion ("Veronica") above.Modern FM receivers do not usually require alignment of the stereo decoders.An FM modulation capability for an RF generator can be useful for checking the FM demodulator.

author: RiRaRi
author_rank: Regular Contributor
timestamp: October 20, 2023, 10:24:18 pm
content: Yes. I understand. In my past i also didnt have any problems with stereo separation but i think it is common problem with receivers from 70s and 80s.But the main part is that this device from ebay cost 390 dollars and Siglent 120MHz cost around 1000 dollars. So maybe this ebay will serve my purpose. It prob produce sine wave which should be enough for my job. Which is testing, aligning AM and FM receivers with only sound and with scope to check any noise on each channel. Am i right?Now i saw one YT video of this ebay device and it says that it can not do stereo but only L, R, L=R, L=-R. But isnt L=R all i need?This Veronica board seems like a good solution to pair with good freq gen but maybe this 390dollars device can do everything i need.

author: TimFox
author_rank: Super Contributor
timestamp: October 20, 2023, 10:34:03 pm
content: From the description, the ABO device should do everything you need for FM receiver adjustment (except for the stereo multiplex function, which needs an external generator).These "AM/FM signal generators" not only include AM and FM capability (with switchable pre-emphasis), but should be usable down to the extremely low signal levels needed to test receiver sensitivity.A general-purpose generator may radiate too much RF field to be used at "-20 dBuV" levels, as shown on the front panel of the ABO unit."Standard signal generators" from the old days used a lot of shielding around the electronics to avoid leakage.What is the specified output range from the Siglent units you are considering, and do they have AM/FM modulation capability?

author: Pomamf
author_rank: Newbie
timestamp: December 24, 2023, 11:10:40 am
content: Thanks for the tip on the Veronica board. I’ve been wondering how I was going to go about getting a stereo signal into some of the 60s era tube receivers I’ve been working on short of buying yet another boat anchor. Great tip!Also, it appears they’re still available.Mike