| Welcome to the official Charlie Tango DX Group CB And Amateur Radio Forum. You are visiting the UK's biggest and most active CB Radio club.. We hope you enjoy your visit. Charlie Tango DX is a group dedicated to Hobby Radio Users in all forms, whether CB, Amateur, PMR446, Scanning and Short Wave Listening. We are a very active and friendly group that welcomes anyone from anywhere in the world who has an interest in Radio, regardless of their level of experience, their equipment, their location, or their radio preference. We have members varying from fully qualified operators on the Amateur Bands, to newcomers who have just bought a PMR446 set, and many CBers both old and new. All are equal on the Site. The CT Site contains many reviews, tips and modifications within the forums, and we take pride that no sensible question is ever left unanswered, and nobody is ever belittled or mocked for asking an honest question, no matter how simple it may seem. We were all new to the hobby once. You're currently viewing our forum as a guest. This means you are limited to certain areas of the board and there are some features you can't use. If you join Charlie Tango you'll be able to access member-only sections, and use member-only features such as customizing your profile, sending personal messages, voting in polls, viewing modifications and more. If you are not yet a member: Registration is simple, fast, and completely free. Simply CLICK HERE to start the Registration process. Your application will need to include your personal name and approximate location, it will require you to confirm your email, and then be signed-off by one of our Admin Staff, but this is usually completed within 24 hours (48 max) |
| Zetagi B300p pre amp failure | |
|---|---|
| Tweet Topic Started: Monday, 5. September 2011, 12:39 (3,135 Views) | |
| NightRunner | Monday, 5. September 2011, 12:39 Post #1 |
26 Charlie Tango 609
![]()
|
My Zetagi B300p pre amp has failed, the amp still works fine ,but when i switch on the pre amp side of it i get no rx at all. Does anyone have knowledge of these things, ie which components are likely to have failed, would appreciate some pointers as were to start as i have little knowledge of electronics and there schematics but would like to have a go at fixing it rather than binning it. |
![]() |
|
| 26CT038Andy | Monday, 5. September 2011, 13:04 Post #2 |
|
26 Charlie Tango 038
![]()
|
Hi Ive got one with the same problem im taking it to my mates on sunday to have it repaired ill let you know when i get it back what the problem is. Andy 26ct038 |
|
FORGET ABOUT TOMORROW BECAUSE TOMORROW NEVER COMES LIVE FAST AND DIE YOUNG | |
![]() |
|
| MadMark1 | Monday, 5. September 2011, 15:59 Post #3 |
|
163 Charlie Tango 020
|
I found this schematic of a B-300-p, Although there are a few different versions of circuit board used in them, saying this though the actual way they all work is proberbly simular. http://i925.photobucket.com/albums/ad100/madmark42/zetagib300-p.gif From the looks of it, The switch marked Pre ( pre-amp ) switches the 12 supply to actually power the pre-amp circiut, the LED on the right of RL2 should light showing power, The coil of RL2 the is switched by the transistor BC237, This looks to be the circuit that actually work the relay to switch the pre-amp in circuit when on rx. The actual pre-amp circuit looks to be the BC237 transistor on the far right of the schematic, I would say its proberbility this transistor at fault, If the relay is switching from tx to rx. check to see if you have voltage on RL2, check the 1N4003 Diode next to the relay, Its across the relay coil ( to stop back Emf ) as it may be short circuit. Also check the 1N914 Diodes, just up from the antenna socket on the schematic as these can go short circuit, there there to protect the pre-amp transistor from strong signals. Mark |
|
Gw0wvl http://www.qrz.com/db/GW0WVL Facebook https://www.facebook.com/groups/1568501233420524/ My Youtube site ... http://www.youtube.com/MrMadjones My website ... http://mjmotorbikes.weebly.com/ My Radio website http://gw0wvl.weebly.com/ "It's not the class of license that the Amateur holds but the class of Amateur that holds the license" | |
![]() |
|
| Deleted User | Monday, 5. September 2011, 16:40 Post #4 |
|
Deleted User
|
The Pre-amp in my B300P is also stuffed. To be honest when it was working it was rubbish so no great loss. I have been told that 'static' can cause the pre-amp to fail. I'm not convinced though:blink: |
|
|
| MadMark1 | Monday, 5. September 2011, 17:55 Post #5 |
|
163 Charlie Tango 020
|
Thats 'True' Bob, The pre-amp is poor on performance, Ok it works but as its a un-tuned circuit it will amplify everything, Including signals that arnt on your channel / frequency, This is what you hear as phantom signals or radio stations. As Bob has said its no real loss in not having the pre-amp working, But on the odd occasion it can be beneficial in having it ... Mark |
|
Gw0wvl http://www.qrz.com/db/GW0WVL Facebook https://www.facebook.com/groups/1568501233420524/ My Youtube site ... http://www.youtube.com/MrMadjones My website ... http://mjmotorbikes.weebly.com/ My Radio website http://gw0wvl.weebly.com/ "It's not the class of license that the Amateur holds but the class of Amateur that holds the license" | |
![]() |
|
| NightRunner | Tuesday, 6. September 2011, 01:41 Post #6 |
26 Charlie Tango 609
![]()
|
Thanks Andy i am interested to here how you get on with it, |
![]() |
|
| NightRunner | Tuesday, 6. September 2011, 01:45 Post #7 |
26 Charlie Tango 609
![]()
|
Thanks Mark, I think it has gone due to a strong signal, as i was close to someone transmitting recently, so i will try and find those protection diodes you mention, although the board looks nothing like the schematic, so i go in search, Rich |
![]() |
|
| Mark in Essex | Tuesday, 6. September 2011, 05:10 Post #8 |
![]()
26 Charlie Tango 037
![]()
|
I also have two sets of B300P and B550P and not a single pre-amp switch working on any of them....never found it a problem as i have always found the pre amps on cheap linear's to be next to useless....will be interested to see if its an easy fix.....not that i'm going to bother doing mine
|
|
[][img][/img][/url] https://www.youtube.com/user/26TANGOMIKE037/videos Nembutol numbs it all But I prefer alcohol | |
![]() |
|
| Radio Pixie | Tuesday, 6. September 2011, 14:09 Post #9 |
|
26 Charlie Tango 052
![]()
|
Best thing to do with B300p preamp is disconnect it internally and replace it with a dedicated "tuned" pre-amp for 27MHz (if you can found one small enough to fit). There are often cheap pre-amps for sell on ebay. Most have gain controls, so just replace with a small pre-set resistor. |
73 from Dave the Pixie 26CT052 - G7OPC - CB & Ham Radioaficionado
| |
![]() |
|
| Pigeon | Tuesday, 6. September 2011, 14:47 Post #10 |
![]()
163 Charlie Tango 014
![]()
|
ive just had a syncron ea 300p nls can you tell me wot power i will get out of it thanks. |
![]() |
|
| 1 user reading this topic (1 Guest and 0 Anonymous) | |
| « Previous Topic · Any Other Radio Equipment · Next Topic » |
| Track Topic · E-mail Topic |
2:43 PM Jul 11
|
All Rights Reserved - No Part Of This Site May Be Copied Without Prior Written Permission. CharlieTango.co.uk have a legal Common Law Trademark and Registered Copyright #S0RN-LTC9-8CXT-LZLU of the brand "Charlie Tango" since 2009 and related Copyrights in place for domain names, Logos, images, format and layout of this website and associated material. charlietango.co.uk & charlietango.uk
View My Stats
DOMAIN NAMES FOR SALE
ConspiracyEffect.com | V5Bid.com Auction | 041183.com | Hiya.Mobi | VR Portal.Net | TrainerSox.com | CoinStealth.com | ChoccyBox.com Domains | FlutterBets.com | CharlieTango.UK | HallmarkedGold.com | MozSubmit.com | HorizontalEarth.com
CharlieTango.co.uk contact email leewardill@gmail.com









2:43 PM Jul 11