|
Homebrew Equipment A place to show, design and discuss the weird and wonderful electronic creations from the hands of individual members. |
|
Thread Tools |
13th Aug 2019, 7:04 pm | #161 |
Dekatron
Join Date: May 2008
Location: Derby, UK.
Posts: 7,735
|
Re: More Chinese AM radio kits
What do you expect when you go borrowing words from other languages willy-nilly? Just as English has different names for an animal when it's alive in a field and dead on your plate, so it has picked up different words for "bonding metals using a molten metal filler" depending on the particular subdomain of engineering. "Welding" and "Soldering" are the same word in many languages.
__________________
If I have seen further than others, it is because I was standing on a pile of failed experiments. |
13th Aug 2019, 10:57 pm | #162 |
Dekatron
Join Date: Feb 2007
Location: Leominster, Herefordshire, UK.
Posts: 16,535
|
Re: More Chinese AM radio kits
Useful, but only if you already know what a superhet is and how it does it!
__________________
....__________ ....|____||__|__\_____ .=.| _---\__|__|_---_|. .........O..Chris....O |
14th Aug 2019, 9:50 am | #163 |
Rest in Peace
Join Date: Sep 2010
Location: Ripley, Derbyshire, UK.
Posts: 785
|
Re: More Chinese AM radio kits
Thanks, Avid Nerdlinger for your handy tip. As it happens, The P.C.B. is marked with the component values, and the Chinglish assembly instructions given in the original ad on Ebay (but, sadly, not with the kit) give the colour/function of the I.F.T.s and transistors, so I should be well away with those clues.
Herald 1360, what you say is very true. I think, given the available instructions, a beginner would be very lucky to successfully build this kit without some help from a knowlegeable person. Fortunately, this project is only being done out of of academic curiosity. Tony. |
14th Aug 2019, 10:17 am | #164 |
Dekatron
Join Date: Jun 2016
Location: London, UK.
Posts: 3,687
|
Re: More Chinese AM radio kits
I’m not exactly a beginner (just built a working superhet from scratch and a K2) and I’ve built two of these Chinese radios and neither of them worked properly so you’re right
I was hoping to modify one a little bit and try and add a BFO. On the IFTs I found a chart of Chinese symbols for colours on the web and used that. Appears the RF side of mine both worked but the audio didn’t. |
22nd Aug 2019, 3:23 pm | #165 |
Rest in Peace
Join Date: Sep 2010
Location: Ripley, Derbyshire, UK.
Posts: 785
|
Re: More Chinese AM radio kits
I put the kit together over the weekend, and it does not function. The problem is in the audio section (uses the one transformer (driver) configuration). Some real jobs have come in meanwhile, so it has had to be put on the Roundtuit shelf for a day or two.
Further investigations will be made shortly. All currents drawn are within the specified limits. Tony. |
22nd Aug 2019, 4:30 pm | #166 |
Triode
Join Date: Mar 2019
Location: Chesterfield, Derbyshire, UK.
Posts: 24
|
Re: More Chinese AM radio kits
Have you bridged all the test point breaks on the PCB? Is the transformer the right way round?
|
22nd Aug 2019, 5:04 pm | #167 | |
Octode
Join Date: Mar 2006
Location: Watford, Hertfordshire, UK.
Posts: 1,270
|
Re: More Chinese AM radio kits
Quote:
__________________
Whether the Top Cap is Grid or Anode - touching it will give you a buzz either way! |
|
27th Jan 2020, 6:08 pm | #168 |
Octode
Join Date: Feb 2018
Location: Southampton, Hampshire, UK.
Posts: 1,061
|
Re: More Chinese AM radio kits
In relation to the long-term reliability of the HX 108-2 kit radio, I am happy to report that mine is still working a year after I successfully built it. It would be interesting to know if other members who built this radio also have had a similar experience.
|
27th Jan 2020, 7:31 pm | #169 |
Pentode
Join Date: Feb 2005
Location: Longfield, Kent, UK.
Posts: 240
|
Re: More Chinese AM radio kits
Mine is still working well after 10 months and with the same batteries. Some of my ceramic capacitors were pretty rubbish when tested before building the radio, so replaced from my stock, otherwise no other problems.
Mike
__________________
Leave me alone - I know what I'm doing. BVWS member, EUG, G-QRP Radio Bygones/Radiophile |
28th Jan 2020, 4:22 pm | #170 |
Octode
Join Date: Feb 2018
Location: Southampton, Hampshire, UK.
Posts: 1,061
|
Re: More Chinese AM radio kits
I had the same experience with the ceramic caps. I didn't use any of the supplied ones.
@bc312: did you make any modifications to the circuit ? |
29th Jan 2020, 12:40 pm | #171 |
Pentode
Join Date: Feb 2005
Location: Longfield, Kent, UK.
Posts: 240
|
Re: More Chinese AM radio kits
No mods to the circuit, however given that other members had experienced problems, I tested every component in the kit - especially caps, transistors, IF transformers and audio transformers - all ok apart from said ceramic caps. The radio worked first time and only needed a tweak of the oscillator coil in order to match the dial frequency markings. I suspect that the kit components are probably manufacturers rejects, so some parts may be near ok, whilst others are out of spec. For the money it was worth a punt and perhaps I was lucky.
Mike
__________________
Leave me alone - I know what I'm doing. BVWS member, EUG, G-QRP Radio Bygones/Radiophile |
10th Feb 2020, 10:45 pm | #172 |
Banned
Join Date: Oct 2015
Location: Cornwall, UK.
Posts: 849
|
Re: More Chinese AM radio kits
Dug my HX108-2 out the other day and ran it for a few hours with no problems at all.
poppydog |
10th Feb 2020, 10:55 pm | #173 |
Octode
Join Date: Feb 2018
Location: Southampton, Hampshire, UK.
Posts: 1,061
|
Re: More Chinese AM radio kits
Thanks. Hopefully the set will stand the test of time over the years. Given the sad and worrying situation in China with electronic production lines starting to be affected, we can only hope that we do not see the last of such interesting and useful kits in spite of their limitations.
|
25th Apr 2020, 9:16 am | #174 |
Nonode
Join Date: Jul 2005
Location: Hull, East Yorkshire, UK.
Posts: 2,085
|
Re: More Chinese AM radio kits
In the context of these kits I built the HX108-2 with 2N3904's in the IF strip which tend to be much higher gain. Too much signal going through I think.
The HX-6B would probably benefit from the use of a 2N3904 as V2 (IF), to give as much gain as possible. I was wondering about if the same transistor is viable as local osc rather than the stock 9018. I am waiting for some more kits that seem to have become delayed somewhere between the PRC & the UK. The image is for guidance. This kit is in full working order. Last edited by Neil Purling; 25th Apr 2020 at 9:30 am. Reason: adding image |
25th Apr 2020, 5:10 pm | #175 |
Nonode
Join Date: Jul 2005
Location: Hull, East Yorkshire, UK.
Posts: 2,085
|
Re: More Chinese AM radio kits
Stuck a 2N3904 in the KX-168 at BG2 (IF) & re-peaked the cores of B1 & B2. It has made quite a difference & would be well worth doing in Europe where the station density & signal levels aren't so high. Therefore it suggests that the S66, HX-6B and other 6 transistor kits will all benefit from the same mod.
The KX-168 had the proper specified 9018H as BG2. Sometimes you don't even get the transistors with the particular gain suffix. |
31st Aug 2020, 11:50 pm | #176 |
Octode
Join Date: Nov 2004
Location: Hebden Bridge, West Yorkshire, UK.
Posts: 1,885
|
Re: More Chinese AM radio kits
I finally got round to building the HX207 that's been waiting for me to get round to it (I got a dose of Covid so I'm a captive audience at the moment).
It seems to have "worked first time" apart from a slight niggle with a broken track - probably caused by my cack-handedness. The current drawn by all the stages was about double what they should have been - I'm hampered by not having my full workshop available, just a B&Q multimeter so that might be what's at fault? I was quite surprised when it burst into life without too much fiddling around. I did substitute the main 100uF cap for a 220uF as the ones that came with the set had quite a poor ESR and I suspect that is what causes a lot of the motorboating and misbehaviour? My daughter loves it and has taken it to bed with her! I'd really like to get it tuned up though. At first Five live (909Khz) appeared on the dial at around 1400 with absolute (1215) at around 1600 with an image of Radio leeds 774 appearing in between. After some (fairly random) fiddling I manage to pull them down closer to where they should be but not great without my signal generator. Does anyone know what the IF frequency should be? D |
1st Sep 2020, 8:36 am | #177 |
Octode
Join Date: Jun 2004
Location: Reading/Fakenham, UK.
Posts: 1,323
|
Re: More Chinese AM radio kits
IF will almost certainly be 455 kHz. Once you've peaked that, getting the LO cct correct and any basic aerial cct trimming done it should be ok.
|
1st Sep 2020, 10:31 am | #178 |
Octode
Join Date: Nov 2004
Location: Hebden Bridge, West Yorkshire, UK.
Posts: 1,885
|
Re: More Chinese AM radio kits
Thanks ian, now to find a sig gen.
|
28th Dec 2020, 10:41 pm | #179 |
Diode
Join Date: Dec 2020
Location: Lasi, Romania.
Posts: 3
|
Re: More Chinese AM radio kits
Hello, today i finished my HX-108 - 2, all 223 capacitors was defective and i replaced them, the sensivity is very good but i have some motorboat sound on lower frecvency about 540khz and on 900khz. I replaced c15 capacitor, what else i can do? the bateries is new alkaline .
|
9th Feb 2021, 2:29 pm | #180 |
Nonode
Join Date: Jul 2005
Location: Hull, East Yorkshire, UK.
Posts: 2,085
|
Re: More Chinese AM radio kits
The HX-108 is push-pull output. I was wondering if substituting the driver and output transformers for a LT400 and LT700 would help the horrible sound quality as they have larger cores. Even speaker substitution did little to fill out the awfully 'tinny' sound.
Given the innaccuracy of the scale 540Khz is close to the IF and 900Khz is the 2nd harmonic of the IF. |