Would you like to react to this message? Create an account in a few clicks or log in to continue.
Welcome to the Charlie Tango DX Group. The home of ALL things Radio - CB, 11m DX, Amateur, PMR446, PLD, Network and Data. We welcome all radio enthusiasts of all knowledge levels. Join today and claim your own unique World Famous CT Call-sign
Starting December 1st - March 31st - 11m Winter Challenge, now taking names, come join us
Call Sign : 26-CT-3228 / M7VIC Posts : 5296 Times Thanked : 339 Join date : 2019-11-10 QTH or Location : Bedford Equipment Used : Various
Subject: Re: Kl 203p HIGH swr Mon Nov 23, 2020 10:54 am
Hi guys,
What I said wasn't specifically knocking any one manufacturer or country of origin.
The circuits are all the same regardless of manufacturer, compare a RM, Zetagi or Chinese knock off KL circuit and they are all basically the same - wide band RF linear amplifiers. (Although the 'linear' aspect can be argued )
The circuit is as old as time, originally using a push/pull valve pair, then transistors, epitaxial RF devices and ultimately MOSFETs. The latter being readily available and cheap as chips hence their use. It's as technology progresses and the next wave of cheap devices become available that we start seeing problems, such as MOSFET devices that can switch at higher frequencies.
The 'Ham' linears are usually much more expensive because they have low pass or even band pass circuits to prevent spurious harmonics being emitted. The CB ones don't add such extra circuitry to keep prices low. (Technically a good basis assuming the CB has decent output filtering - but they usually don't.)
These type of amps used to be advertised as CB linears with a typical 26-28MHz range, they now get advertised as 26-30MHz to capture the 10m Ham market. (They're still the same things!) A lot of Hams used to change the MOSFETs out on them to make up cheap 6m amps and indeed nowadays they can be used 'off the shelf' for such frequencies.
Hence my original point, if you are amplifying any harmonics, (especially the secondary at 54-56MHz), it will show a poor SWR when running. The SWR meter won't differentiate what frequency is coming back, just how much.
But I agree Martin, places such as RM and Zetagi etc. have reputations to keep and I personally don't know their supply or manufacturing chain. I just know the circuitry is the same....
Anyway, all of this was trying to help out the original OP with a problem - it'll probably turn out his second hand amp is a duff one. But if you have a nice new shiny rig, new linears and have got a SWR problem....then this knowledge just might help
Just sling in a cheap TVI filter.
All the best, Victor
NUBSTER likes this post
The author of this message was banned from the forum - See the message
NUBSTER 10 + Year member
Call Sign : 26 CT050 26 FB080 26 WT105 26 TE171 Posts : 948 Times Thanked : 51 Join date : 2019-06-27 QTH or Location : NORTH LONDON Equipment Used : ORIGINAL President Lincoln, President Teddy , Silver Eagle microphones , Gainmaster antenna, use a AMP ofcourse I do sometimes Age : 65
Subject: Re: Kl 203p HIGH swr Mon Nov 23, 2020 11:35 am
TBH my preference is a old valve amp but nobody seems make them now well not that I know of ,perhaps some specialist radio manufacturers may do custom ones ,I use to have one once OK it use take about 5/10mins to warm up and you had to tune it (plate and load) but I never had any problem with it apart from as time went on I found it a bit harder to find the valves for it ,then someone offered me a nice price to take it off my hands ,don't know the make of it as it was a homemade one i think had no name on it, because I brought it second hand anyway myself.
Victor likes this post
Victor CT Directors
Call Sign : 26-CT-3228 / M7VIC Posts : 5296 Times Thanked : 339 Join date : 2019-11-10 QTH or Location : Bedford Equipment Used : Various
Subject: Re: Kl 203p HIGH swr Mon Nov 23, 2020 12:12 pm
I miss my old Bremi BRL500's Martin (Used to have some BRL300's too!)
Nothing like that Pi-Network tuning output!
There used to loads of the old PL509/519 handmade jobs around but I haven't seen a set in years.
If anyone reading this doesn't know, the PL509 was a line output or 'sweep' thermionic valve that used to be common in TV sets right up till the early 1980's. Cheap as chips and could be pushed into service as RF linears. Quite often you could dig them out of discarded TV sets so getting them for free!!
Bit harder to stick in the car mobile though Martin!
Flip me, happy days. There are new valve amps available nowadays but be prepared to break the old credit card!
NUBSTER likes this post
The author of this message was banned from the forum - See the message
NUBSTER 10 + Year member
Call Sign : 26 CT050 26 FB080 26 WT105 26 TE171 Posts : 948 Times Thanked : 51 Join date : 2019-06-27 QTH or Location : NORTH LONDON Equipment Used : ORIGINAL President Lincoln, President Teddy , Silver Eagle microphones , Gainmaster antenna, use a AMP ofcourse I do sometimes Age : 65
Subject: Re: Kl 203p HIGH swr Mon Nov 23, 2020 2:11 pm
I will admit Victor I didn't know that about old TV valves was the same or could be used to build amps ,my electronics skills in that dept is nill, we used to have in my area a proper old school large electrical shop who sold everything and the old boy who owned it knew everything too so that's where most of us went to and got things like valves and other radio stuff TBH anything to do with electronics,there was always a load of knowledge of electrical stuff to be learnt in that shop from the old boy and his staff plus other customers, not all radio I will say because it wasn't a radio shop as such but as time went on and electrical stuff became disposable products he business slowly dried up and when he passed away the shop just shut down, shame none of his staff took it over but as I siad most electrical goods was coming from Hong Kong/China made cheap sold cheap so chuck it when broken so no one bothered I suppose, but that was a brilliant shop. RIP Frank Mozer Owner of Frank Mozers Electronics Edmonton North London
Victor likes this post
Victor CT Directors
Call Sign : 26-CT-3228 / M7VIC Posts : 5296 Times Thanked : 339 Join date : 2019-11-10 QTH or Location : Bedford Equipment Used : Various
Subject: Re: Kl 203p HIGH swr Mon Nov 23, 2020 3:50 pm
We could have a whole new thread on that Martin!
I remember Frank Mozer's and Crescent Radio. There were more electronic shops in London and surplus outlets than you could shake a stick at. Edgware Rd was full of them, I think Smith's (?) was the big one. I used to do a run for spares, D P Hobbs in Luton, Surplatronics also, if they didn't have the part then onto Watford and often finally landed up in London. I remember a surplus warehouse outlet at Waltham Cross too, can't remember their name but loved the old 'Pie & Mash' shop round the corner! Warmed me up for the motorbike journey back home.
Ha! Definitely off topic now mate!
NUBSTER likes this post
The author of this message was banned from the forum - See the message
NUBSTER 10 + Year member
Call Sign : 26 CT050 26 FB080 26 WT105 26 TE171 Posts : 948 Times Thanked : 51 Join date : 2019-06-27 QTH or Location : NORTH LONDON Equipment Used : ORIGINAL President Lincoln, President Teddy , Silver Eagle microphones , Gainmaster antenna, use a AMP ofcourse I do sometimes Age : 65
Subject: Re: Kl 203p HIGH swr Mon Nov 23, 2020 3:57 pm
Sorry mate and others to go off topic but I just wanted to share that memory, Crescent Radio is still there but it's just a very very small shop now in a side street it use to be on the corner of the same street but sold out to move to smaller premises,bit of a coincidence you knew Mozers.
Victor likes this post
Victor CT Directors
Call Sign : 26-CT-3228 / M7VIC Posts : 5296 Times Thanked : 339 Join date : 2019-11-10 QTH or Location : Bedford Equipment Used : Various
Subject: Re: Kl 203p HIGH swr Mon Nov 23, 2020 4:48 pm
No worries Martin, off topic can be enjoyable
We've probably been stood right next to each other and never even known mate Such is the strange world we live in.
NUBSTER likes this post
Mitch Contributor
Call Sign : M1TCH Posts : 72 Times Thanked : 8 Join date : 2020-01-02 QTH or Location : Leicester Equipment Used : Yaesu FT-857D, Diamond V2000, Major 3000, President Jackson Mk1, Lafayette AFS-1005, K40 mic, KL203, B550P and Sirio GPE 27 ⅝λ.
Subject: Re: Kl 203p HIGH swr Mon Nov 23, 2020 5:20 pm
@21ASN93 Where are you measuring the SWR, exactly? Do you have any power output from the amp into the aerial (or dummy load)? Is there any output to the aerial with the amp connected but switched off?
43CT016 Major contributor
Call Sign : 43-CT-016 Posts : 343 Times Thanked : 22 Join date : 2019-11-17 QTH or Location : Perth Equipment Used : iCom IC-7610/IC-9700
Subject: Re: Kl 203p HIGH swr Tue Nov 24, 2020 9:25 am
Victor wrote:
We could have a whole new thread on that Martin!
I remember Frank Mozer's and Crescent Radio. There were more electronic shops in London and surplus outlets than you could shake a stick at. Edgware Rd was full of them, I think Smith's (?) was the big one. I used to do a run for spares, D P Hobbs in Luton, Surplatronics also, if they didn't have the part then onto Watford and often finally landed up in London. I remember a surplus warehouse outlet at Waltham Cross too, can't remember their name but loved the old 'Pie & Mash' shop round the corner! Warmed me up for the motorbike journey back home.
Ha! Definitely off topic now mate!
I remember the first (and only "proper") Maplins at Hammersmith before they tried to be a retail consumer electronics chain!
There was Crescent Radio, Watford Electronics, and some other mob who advertised in the radio and electronics mags of the day that I got all my cheap components form in mixed bags...can't remember the name, but as a schoolkid, money was tight!
Can't remember the one at Waltham Cross though....what year are we talking? I might have found someone older than me!
Re the amps...a lot of the Ameritron amps are valve, and are significantly cheaper than the newer solid state ones for a given power output. If any of the US vendors do them in the Black Fridays sales though, I'm treating myself to the solid state ALS-500M, as it's a "no tune" amp and with our power limit being only 400w PEP and me running a 12v/solar station, it's ideal.
Last edited by 43CT016 on Tue Nov 24, 2020 11:05 am; edited 1 time in total
Victor likes this post
Victor CT Directors
Call Sign : 26-CT-3228 / M7VIC Posts : 5296 Times Thanked : 339 Join date : 2019-11-10 QTH or Location : Bedford Equipment Used : Various
Subject: Re: Kl 203p HIGH swr Tue Nov 24, 2020 10:50 am
Hi Jeff, (We're totally off topic now, I'm a terrible admin )
Yeah Maplin, I still remember the spaceship on their '79 catalogue! Mixed bags of components - the old 'Bargain Bags'? Waltham Cross was a guys warehouse, think his main shop was on the Edgeware road, used to do me the odd deal 1980's Jeff.
Luuuuv Ameritrons! Would build a valve linear in a heartbeat....apparently Foundation doesn't allow me to
Right, slapped wrists all round. We'll haver to start our own "Trips Down Memory Lane" posting.
NUBSTER likes this post
43CT016 Major contributor
Call Sign : 43-CT-016 Posts : 343 Times Thanked : 22 Join date : 2019-11-17 QTH or Location : Perth Equipment Used : iCom IC-7610/IC-9700
Subject: Re: Kl 203p HIGH swr Tue Nov 24, 2020 11:06 am
Victor wrote:
Hi Jeff, (We're totally off topic now, I'm a terrible admin )
Right, slapped wrists all round. We'll haver to start our own "Trips Down Memory Lane" posting.
A proper admin would split the topic and spawn the new one for us old buggers.
NUBSTER and Victor like this post
GaryWilson CT Directors
Call Sign : 26-CT-1836 Ham 2E0GGQ Posts : 4018 Times Thanked : 335 Join date : 2019-06-27 QTH or Location : Braunston Northamptonshire. Equipment Used : Radios & Wires & Stuff! Age : 59
Subject: Re: Kl 203p HIGH swr Tue Nov 24, 2020 11:42 am
Just a thought, did you re-calibrate the SWR meter after putting the amp in-line?
73's Gary.
NUBSTER likes this post
The author of this message was banned from the forum - See the message
NUBSTER 10 + Year member
Call Sign : 26 CT050 26 FB080 26 WT105 26 TE171 Posts : 948 Times Thanked : 51 Join date : 2019-06-27 QTH or Location : NORTH LONDON Equipment Used : ORIGINAL President Lincoln, President Teddy , Silver Eagle microphones , Gainmaster antenna, use a AMP ofcourse I do sometimes Age : 65
Subject: Re: Kl 203p HIGH swr Tue Nov 24, 2020 11:48 am
GaryWilson wrote:
Just a thought, did you re-calibrate the SWR meter after putting the amp in-line?
73's Gary.
I did explain that to him Gary and didn't really get a answer from the OP unless there was a misunderstanding in translation as the OP is Swedish and admit his English wasn't that good .lol
GaryWilson likes this post
Northern Crusader Major contributor
Call Sign : M0GVZ / 26CT1760 Posts : 514 Times Thanked : 35 Join date : 2019-11-13 QTH or Location : IO94SA Equipment Used : Icom 7300, TS480, President McKinley, Albrecht AE6110, CRT Mike Age : 53
Subject: Re: Kl 203p HIGH swr Wed Nov 25, 2020 2:19 pm
NUBSTER wrote:
TBH my preference is a old valve amp but nobody seems make them now well not that I know of
There are plenty of manufacturers.
OM Power do a whole range including a 4kW one... Acom do several. The Ameritron AL80 is still available to buy new along with several others they do
The author of this message was banned from the forum - See the message
NUBSTER 10 + Year member
Call Sign : 26 CT050 26 FB080 26 WT105 26 TE171 Posts : 948 Times Thanked : 51 Join date : 2019-06-27 QTH or Location : NORTH LONDON Equipment Used : ORIGINAL President Lincoln, President Teddy , Silver Eagle microphones , Gainmaster antenna, use a AMP ofcourse I do sometimes Age : 65
Subject: Re: Kl 203p HIGH swr Wed Nov 25, 2020 2:46 pm
Cheers Coner I will have a look at that link.
GaryWilson CT Directors
Call Sign : 26-CT-1836 Ham 2E0GGQ Posts : 4018 Times Thanked : 335 Join date : 2019-06-27 QTH or Location : Braunston Northamptonshire. Equipment Used : Radios & Wires & Stuff! Age : 59
Subject: Re: Kl 203p HIGH swr Wed Nov 25, 2020 4:45 pm
NUBSTER wrote:
GaryWilson wrote:
Just a thought, did you re-calibrate the SWR meter after putting the amp in-line?
73's Gary.
I did explain that to him Gary and didn't really get a answer from the OP unless there was a misunderstanding in translation as the OP is Swedish and admit his English wasn't that good .lol
Sorry Martin, it's the only thing I could think of that would be an obvious oversight, I missed that detail in your reply.
Stay safe buddy.
73's Gary.
The author of this message was banned from the forum - See the message
NUBSTER 10 + Year member
Call Sign : 26 CT050 26 FB080 26 WT105 26 TE171 Posts : 948 Times Thanked : 51 Join date : 2019-06-27 QTH or Location : NORTH LONDON Equipment Used : ORIGINAL President Lincoln, President Teddy , Silver Eagle microphones , Gainmaster antenna, use a AMP ofcourse I do sometimes Age : 65
Subject: Re: Kl 203p HIGH swr Wed Nov 25, 2020 6:33 pm
No worries Gary mate I've explained Victor has done the same so it's down to him to sort it now.
joistein New Member
Posts : 1 Times Thanked : 0 Join date : 2020-12-25 QTH or Location : Gothenburg, Sweden Equipment Used : CRT SS 9900 Yeasu ft 817 etc
Subject: Re: Kl 203p HIGH swr Fri Dec 25, 2020 2:22 pm
Victor wrote:
The question's already been asked but the commonest SWR problems I've seen is placement of the SWR meter.
21ASN93, are you connected like this? :-
RIG <-----> KL203 Linear <-----> SWR Meter <-----> ANTENNA
Some will argue about this but I've never seen the point of measuring the 'linear' SWR(?) only the power input to it.
Also remember "Crap In = Crap Out"
If you have a rig kicking out spurious harmonics, (54-56Mhz is not unusual), the linear is so wide-banded it will amplify the harmonics as well!! The typical CB SWR meter is also wide-banded, (3-200Mhz in some cases), and can't differentiate the harmonic crap coming back. Obviously your antenna is tuned to ~27Mhz and all that amplified harmonic content will come crashing back down showing you a high SWR.
How do you fix it?
A typical TVI filter will cut down the amount of harmonic crap your rig is kicking out before you start amplifying it. (Should've been done in the radio but low pricing/cheap manufacturing ie Chinese means it usually isn't!)
So :-
RIG <-----> TVI Filter <-----> LINEAR <-----> SWR Meter <-----> ANTENNA
That usually fixes common 'linear' SWR problems right off the bat.
Some manufacturers tell you to cut a certain length of coax for the rig to linear connection, it's usually a vain attempt at impedance matching and hopefully reducing your harmonic content along the way. The 'TVI Filter' will usually fix your impedance as well as reduce harmonics and provide a much needed fix for poorly designed MOSFET to MOSFET connectivity.
(We didn't get these issues with the old transistor & valve stuff did we fellow 'old gits' )
Often operators ignore all the above as the rig & linears don't 'blow up' and merrily transmit harmonics all over the place.........
Anyway, hope that helps the OP, anyone else reading this or even if anyone bothers to search the forum in future
All the best, Victor
I have always had Rig>>Amp>>ATU/SWR >>Low pas filter>>ANT. RM Italy recommend you to use Low pas filter.
chazwozza Senior contributor
Posts : 114 Times Thanked : 1 Join date : 2020-02-15 QTH or Location : England Equipment Used : Radios
Subject: Re: Kl 203p HIGH swr Tue Mar 02, 2021 9:14 pm