|
Vintage Amateur and Military Radio Amateur/military receivers and transmitters, morse, and any other related vintage comms equipment. |
|
Thread Tools |
25th Jul 2014, 2:23 pm | #101 |
Dekatron
Join Date: Apr 2012
Location: Wiltshire, UK.
Posts: 13,996
|
Re: Activity on 80 metres?
Or rather than a big MOSFET, you could undoubtedly use one of the high-voltage switching transistors from a dead compact-fluorescent lamp as the modulator stage.
I recall back in the 1980s building 2-stage 'high voltage class-A' transistor amplifiers using a standard valve-type output transformer and something like a MJE340 plastic power TO220 transistor or whatever could be scavenged from dead 'hybrid' TVs . DC stabilisation was by taking the voltage across the MJE340's emitter-resistor as bias for the driver stage (which was usually something like a 2N3053). Gain/power/quality was as good as the likes of an ECL86 and the component-count was lower. |
25th Jul 2014, 6:03 pm | #102 |
Nonode
Join Date: Mar 2005
Location: Nuneaton, Warwickshire, UK.
Posts: 2,038
|
Re: Activity on 80 metres?
Here's an article from 1986. It's a transceiver for topband, but could probably be modified for 80 without too much difficulty. The IFTs in the receiver are a but rare now, but all other components should still be obtainable.
73's Aub
__________________
Life's a long song, but the tune ends too soon for us all. |
25th Jul 2014, 6:06 pm | #103 |
Nonode
Join Date: Mar 2005
Location: Nuneaton, Warwickshire, UK.
Posts: 2,038
|
Re: Activity on 80 metres?
Here's the last two.
__________________
Life's a long song, but the tune ends too soon for us all. |
25th Jul 2014, 6:24 pm | #104 |
Octode
Join Date: Jun 2011
Location: West Midlands, UK.
Posts: 1,571
|
Re: Activity on 80 metres?
They were talking about top band nostalgia in 1986. (A mere 28 years ago!)
Actually, I'd like an AT5 as I still have a T28 receiver. |
26th Jul 2014, 3:31 pm | #105 |
Dekatron
Join Date: Nov 2003
Location: Heckmondwike, West Yorkshire, UK.
Posts: 9,642
|
Re: Activity on 80 metres?
One post moved to a new thread: https://www.vintage-radio.net/forum/...d.php?t=107966
|
26th Jul 2014, 4:02 pm | #106 |
Heptode
Join Date: Jan 2003
Location: Tewkesbury, Gloucestershire, UK.
Posts: 693
|
Re: Activity on 80 metres?
Hi Aub,
Worth noting that there's an error on the modulator circuit. There should be a capacitor between the first anode of the ECC83 and the slider of the gain potentiometer - otherwise the second triode is not going to be very happy! (In fact I would also have put the pot the other way round, i.e. slider to grid, to avoid changes to the roll-off frequency with mod level setting). You wonder sometimes whether the authors ever build and test their own circuits...
__________________
Keith Yates - G3XGW VMARS & BVWS member http://www.tibblestone.com/oldradios/Old_Radios.htm |
26th Jul 2014, 5:25 pm | #107 |
Nonode
Join Date: Mar 2005
Location: Nuneaton, Warwickshire, UK.
Posts: 2,038
|
Re: Activity on 80 metres?
Hi Keith,
Oh yes. I hadn't noticed that or, at least, I can't remember noticing it. I've had those magazines since they were new and I never built the thing, although I always fancied making the receiver and moding it for 80. I have the IFTs, from when they started making them again, briefly, in the late nineties. 73 Aub
__________________
Life's a long song, but the tune ends too soon for us all. |