[Boatanchors] Golden Falcon Linear Amplifier Questions

[Tom in N Texas]

Message: 2
Date: Sun, 01 Jun 2003 10:42:44 -0400
From: "Patrick A. Thompson Sr." <wa4tukhr@comcast.net>
Subject: RE: [Boatanchors] Golden Falcon Linear Amplifier Questions
To: Tom in N Texas <tdulin@pulse.net>, boatanchors@mailman.qth.net

PAT SAYS: I'm pretty sure this amp was really directed at the 11 meter 
crowd and is part of the reason there were restrictions put on ham 
amplifiers regarding 28 MHz coverage and allowable drive power.

TOM REPLIES: First, I have taken a little more careful look at the 
amplifier. It is two parallel 6FX6's driving four parallel 6LF6's, all 
grounded-grid, so it doesn't really have a preamp. Sorry about the 
misleading information. It has a 40-20-15-10 band switch which switches 
driver plate inductor taps,  and output plate inductor taps and also 
switches the gangs of a three-gang variable capacitor to couple the antenna.

I think this takes it out of the built-for-CB category. John WB6BLV tells 
me  that the Golden Falcon was made by Tecraft, now defunct. I found a 
couple of other things they made, including six-meter rigs. I expect they 
also made CB junk.

PAT: It was intended to be driven with the 3 watts or so from an ordinary 
CB hence the preamp. If I'm correct the preamp then drove the pair of sweep 
tubes. The amp probably incorporated an RF sensing circuit to put it into 
transmit without an external relay closure.

TOM: It does have an RF sensing circuit, and no external connections except 
power and in and out. I wonder how much power it would take to drive the 
grounded-grid 6LX6's

PAT- These types of amps have a poor reputation for intermod etc. but it 
might be possible to get a clean signal out by careful tuning and avoiding 
overdrive. So it might find some use in your shack driven with a low power 
or QRP type rig perhaps with an input padding network. (attenuator).

TOM: I can believe problems with spurs, the PS filter seems to be two 
100MFD capacitors in series, and, I suppose, a resistor. not much 
filtering. I haven't a clue how the tubes are biased, a little hard to dig 
out by tracing wires. Antenna coupling is through a variable capacitor, 
high pass.

PAT I have no idea where to get a schematic although a quick "Google" search
found some dealers selling a schematic for a "Golden Falcon 2000".

TOM: On Google, I found a schematic for four dollars and a book for thirty 
dollars. But both seem to be for CB amplifiers.

PAT- Assuming you didn't pay too much the power transformer alone may be 
worth the purchase price.

TOM: I found that the 6LF6's are priced on the Internet from $3.75 to $85+? 
I'm thinking of buying the $3.75 ones and selling at $85 for audio nuts. hi

I could sell 6 tubes and the power transformer and get at least ten times 
the purchase price!    8>))    I'm not very good at making that work, even 
at HamCom.

Pat
wa4tuk
--------------------
I'm still intrigued by it. I see three problems: It should probably be 
re-biased to improve linearity, add power supply filtering and address the 
high-pass antenna coupling. And, of course, avoid over-driving it.

I would still like to see a schematic. It has three relays and associated 
wiring. I'd hate to have to draw all that wiring with nothing to go from.

Tom KC5INU

Tom in N Texas, KC5INU,  EM12jk, RARA 025, QRPp-I 353, NETXQRP  33, QCWA 
31587, tdulin@pulse.net,
  Hallicrafters SX-71, S-38, S-38D, National NC-300, Johnson Viking Ranger,
Knight TR106, Heath SB-101, "Sixer", IO-10, V-7 VTVM, etc., etc.