Buying a transceiver, tests - Page 1
Forum section: electronics / rf-microwave

author: CJay
author_rank: Super Contributor
timestamp: August 14, 2017, 06:58:32 pm
content: So if you were buying a HF transceiver, what tests would you want to carry out before handing over your cash?Bear in mind I am not (for another 2 weeks) licenced but the opportunity to get my hands on a bargain will pass this weekend.So, i'm thnking I need a sig gen, a receiver, apower meter and dummy load?

author: Wirehead
author_rank: Regular Contributor
timestamp: August 14, 2017, 07:59:43 pm
content: Check if the transceiver can obviously receive, all buttons and functions work, TX works at full power in CW keydown (test on dummy load) and check with a frequency meter if the frequency of the VFO matches with what you've actually set it at.Also, if you're buying from a ham and all of a sudden he doesn't have an antenna to let you listen, or he can't show you key-down power on CW: slowly walk away

author: TheSteve
author_rank: Unknown
timestamp: August 14, 2017, 08:04:41 pm
content: Hopefully the seller has a good power supply - if not, bring one. I like to test tx/rx on each band. Then test the preamp/attenuator if so equipped. If it has a builtin antenna tuner it is wise to test that as well as they are a high failure point.Can you tell us the model of the rig, there might be more specific items we can suggest to check. An example would be if the radio has a built in USB port - it would be wise to test it if it does.

author: CJay
author_rank: Super Contributor
timestamp: August 15, 2017, 05:37:25 am
content: The seller's in the middle of building a house and it was his father's radio, I think it's a silent key sale but he doesn't know the terminology, just that it has a value.He's done a little research on the net for prices and is on the low side (knows so too) but very happy to sell to me as I'm willing to make the effort to collect it (I'm combining it with a short break so it makes it easier)Bargains always make me nervous...He has hinted that he has a lot of other equipment so there may be a PSU but I can't bank on it, I'm charging a 17AH SLA to take with me just in caseI've dug out my power meter and dummy load, I can knock together a simple DDS VFO to to take with so I can at least listen to that and I have one of the cheap Chinese 'cymometer' frequency counters I can take (nicely accurate) or one of my Racals but I may not have access to mains power.The radio is an Icom IC718 with antenna tuner, pretty basic but I think it'd be a good 'getting started' radio until I get my intermediate licence when I can start using my own creations on air.

author: vk3yedotcom
author_rank: Frequent Contributor
timestamp: August 15, 2017, 09:48:24 am
content: Two suggestions1. Receiver. Turn on, set to SSB receiver on any band put in a few metres of wire into the antenna socket. There should be a substantial increase in noise. If not make sure the RF gain is set to max and attenuator is switched out. You may even hear some signals (tune to AM broadcast band if your receiver covers it). If you can hear AM stations you can try different audio filter options.2. Transmitter. Attach a dummy load, press PTT, go to SSB and talk into microphone. Meter needle should move, showing power out (if that's the function your meter is switched to). If not check mic gain and power out controls. Also the frequency is in an amateur band.

author: TheSteve
author_rank: Unknown
timestamp: August 15, 2017, 06:35:06 pm
content: The 718 is a very nice basic radio that is known to have amazing transmit audio quality. From what I've read they are also quite reliable. So if basic tx/rx works you're likely good to go. Icom also releases service manuals and schematics in case there ever is an issue. There were some early 718's released without the audio DSP filter - it is a feature that is very nice to have.

author: CJay
author_rank: Super Contributor
timestamp: August 15, 2017, 06:52:22 pm
content: Ah, useful to know, was there a serial number range that would identify if it had the DSP or not?