UK Vintage Radio Repair and Restoration Powered By Google Custom Search Vintage Radio and TV Service Data

Go Back   UK Vintage Radio Repair and Restoration Discussion Forum > Specific Vintage Equipment > Vintage Amateur and Military Radio

Notices

Vintage Amateur and Military Radio Amateur/military receivers and transmitters, morse, and any other related vintage comms equipment.

Reply
 
Thread Tools
Old 23rd Nov 2023, 7:24 pm   #1
Alan G0EAG
Triode
 
Join Date: Dec 2017
Location: Herne Bay, Kent, UK.
Posts: 16
Default Cirkit 20w HF amplifier

Has anyone got any info or the specs on the Cirkit HF 20w HF amplifier?
Alan G0EAG is offline   Reply With Quote
Old 23rd Nov 2023, 7:50 pm   #2
David G4EBT
Dekatron
 
David G4EBT's Avatar
 
Join Date: Feb 2003
Location: Cottingham, East Yorkshire, UK.
Posts: 5,766
Default Re: Cirkit 20w HF amplifier

Quote:
Originally Posted by Alan G0EAG View Post
Has anyone got any info or the specs on the Cirkit HF 20w HF amplifier?
I built it goodness knows when, (early 90s?), as a PA for the G-QRP 'Epiphyte' 5 Watt SSB 80M transceiver, which I also built, but later disposed of. It featured in 'Ham Radio Today' magazine - I'm not sure which issue, but you can view all of them to find it at this link:

https://www.worldradiohistory.com/Ham_Radio_Today.htm

I don't have the article any more, but I've attached a portion of it which shows a wiring error on the component overlay which I discovered. (Highlighted in yellow on pic 1).

Pic 2 shows the PCB, which was easy to etch by applying 'Fablon' sticky backed plastic to the laminate, gluing the paper layout onto that, and cutting away the plastic to the outline, leaving the rest of the plastic to act as the etch resist. The components were mounted on the tinned pads.

It used four CB transistors, which are I think, long since obsolete.

Pic 1: Wiring error on connections E & F on T2 in the magazine article. As show in the diagram, those connections would have been shorted out to each other.
Pic 2: Shows the PCB etching pattern, as well as the component overlay.

Hope that helps a bit.
Attached Thumbnails
Click image for larger version

Name:	CIRKIT HF PA OVERLAY CORRECTION_edited-2 copy.jpg
Views:	99
Size:	54.3 KB
ID:	288626   Click image for larger version

Name:	Cirkit HF PA PCB & Layout.jpg
Views:	102
Size:	100.9 KB
ID:	288627  
__________________
David.
BVWS Member.
G-QRP Club member 1339.
David G4EBT is online now   Reply With Quote
Old 23rd Nov 2023, 8:43 pm   #3
Cruisin Marine
Octode
 
Join Date: Jul 2018
Location: Worthing, West Sussex, UK.
Posts: 1,003
Default Re: Cirkit 20w HF amplifier

I am pretty sure it was featured in an ussue of R & EW magazine, can't remember which issue now?
__________________
"Behind every crowd, there's a silver Moonshine"
Cruisin Marine is offline   Reply With Quote
Old 23rd Nov 2023, 9:46 pm   #4
m0cemdave
Octode
 
Join Date: Feb 2009
Location: Bletchley, Buckinghamshire, UK.
Posts: 1,223
Default Re: Cirkit 20w HF amplifier

It's in R&EW, September 1983, pp 60-66.
m0cemdave is offline   Reply With Quote
Old 23rd Nov 2023, 10:00 pm   #5
Jon_G4MDC
Nonode
 
Jon_G4MDC's Avatar
 
Join Date: Nov 2015
Location: Welwyn Garden City, Hertfordshire, UK.
Posts: 2,015
Default Re: Cirkit 20w HF amplifier

It was very good. I still have a Swan 102BX, mostly used for Top Band, where it replaced the very dicky original 100W PA of the Swan.

Perfect. Almost no chance of exceeding the licence condx.
Jon_G4MDC is offline   Reply With Quote
Old 23rd Nov 2023, 10:45 pm   #6
Radio Wrangler
Moderator
 
Radio Wrangler's Avatar
 
Join Date: Mar 2012
Location: Fife, Scotland, UK.
Posts: 22,901
Default Re: Cirkit 20w HF amplifier

I think it's better known as the Chris Honey amplifier. There's a CH logo on the board.

David
__________________
Can't afford the volcanic island yet, but the plans for my monorail and the goons' uniforms are done
Radio Wrangler is online now   Reply With Quote
Old 23rd Nov 2023, 11:58 pm   #7
David G4EBT
Dekatron
 
David G4EBT's Avatar
 
Join Date: Feb 2003
Location: Cottingham, East Yorkshire, UK.
Posts: 5,766
Default Re: Cirkit 20w HF amplifier

Quote:
Originally Posted by m0cemdave View Post
It's in R&EW, September 1983, pp 60-66.

So it was! Here’s the link:

https://www.worldradiohistory.com/UK...EW-1983-09.pdf

Brings to mind the opening lines of Mary Hopkin’s song:

‘Those were the days my friends, we’d thought they’d never end’……
__________________
David.
BVWS Member.
G-QRP Club member 1339.
David G4EBT is online now   Reply With Quote
Old 24th Nov 2023, 2:26 pm   #8
Alan G0EAG
Triode
 
Join Date: Dec 2017
Location: Herne Bay, Kent, UK.
Posts: 16
Default Re: Cirkit 20w HF amplifier

Thanks for all the info. I picked one up recently at a SK sale. It was part of a incomplete homebrew HF transceiver using a G4CLF exciter board. I plan to rebuild the rig with a JF3HZB digital VFO
Alan G0EAG is offline   Reply With Quote
Old 24th Nov 2023, 6:51 pm   #9
Radio Wrangler
Moderator
 
Radio Wrangler's Avatar
 
Join Date: Mar 2012
Location: Fife, Scotland, UK.
Posts: 22,901
Default Re: Cirkit 20w HF amplifier

Remember that it's just a raw power amp and needs low pass filters on its output to suit the band you're using it on.

I used to use one of these as the output PA for a Redifon GK203 multimode HF exciter, so I did a family of LPFs for the HF bands and used a 2 pole multiway swtch to connect them.

David
__________________
Can't afford the volcanic island yet, but the plans for my monorail and the goons' uniforms are done
Radio Wrangler is online now   Reply With Quote
Old 25th Nov 2023, 3:05 pm   #10
Alan G0EAG
Triode
 
Join Date: Dec 2017
Location: Herne Bay, Kent, UK.
Posts: 16
Default Re: Cirkit 20w HF amplifier

Hi David, I'll be using bandpass filters on the input / output of the G4CLF board and LPFs on the output of the amp. I need to check if the squarewave output from the SI5351 into the CLF diode mixer will be ok.
Alan G0EAG is offline   Reply With Quote
Old 25th Nov 2023, 11:06 pm   #11
Radio Wrangler
Moderator
 
Radio Wrangler's Avatar
 
Join Date: Mar 2012
Location: Fife, Scotland, UK.
Posts: 22,901
Default Re: Cirkit 20w HF amplifier

Diode mixers work well with fast squarewave LO drive. They work even better still with a fast squarewave of current!

Intermod products reduce with increased dv/dt of the LO. The steeper slope means that signal port voltages have less effect in modulating the switching instant of the diodes.

The poor little diodes are one port devices. They see only one voltage, only one current. There is no discrimination between signal and LO. Therefore strong signals start looking like an additional component of LO and the rest is history.

In HP journal April 1982 there is an article by Guy Douglas and myself on pushing diode mixers to pretty much the limit. Guy did the mixer itself and I designed a synthesiser-driver around it. A symmetric squarewave also helped so we used a synth at twice the frequency we first thought of, followed by a fast ECL divide-by-two. This bought us a few more dB of dynamic range.

David
__________________
Can't afford the volcanic island yet, but the plans for my monorail and the goons' uniforms are done
Radio Wrangler is online now   Reply With Quote
Reply

Thread Tools



All times are GMT +1. The time now is 5:00 pm.


All information and advice on this forum is subject to the WARNING AND DISCLAIMER located at https://www.vintage-radio.net/rules.html.
Failure to heed this warning may result in death or serious injury to yourself and/or others.


Powered by vBulletin®
Copyright ©2000 - 2024, vBulletin Solutions, Inc.
Copyright ©2002 - 2023, Paul Stenning.