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Gordon Gibby
¿ªÔÆÌåÓý?Wow.....Kee's kits are an incredible list of projects.? ?I'm blown away by his productivity.? ? Perhaps when I retire I'll be able to do more kit building!!!
gordon
From: [email protected] <[email protected]> on behalf of K9HZ <bill@...>
Sent: Monday, May 28, 2018 8:08 PM To: [email protected] Subject: Re: [BITX20] RF power chain mods and improvements.. ?
Calculating the impedance, the transformer has to be closer to 1:2 for this device at 13.6V.? I use a ?BN61-002 and it seems to be the winner for me so far (more efficient than the 43 type material), but others have found that a 1:2 BD43-302 works ok too.? Doesn¡¯t heat up at full power and is extremely wide banded¡? You should look at the references on Kees website (K5BCQ Kits) regarding his 20W RD16HHF1 transistorized amplifier.?? They will give you good information. ? ? ? ? ? ? Dr. William J. Schmidt - K9HZ ? From: [email protected] [mailto:[email protected]]
On Behalf Of Ralph Mowery ? I have replaced the finals with the RD16hhf1 from RF Parts, capacitors across R 87,88,? feedback on finals to 1 K and the binocular output transformer.? I have seen several values of capacitors across the transformer and tried a couple.? Right now I am using 150 pf .? I am using the 2 turns/ 3 turns on the output. ? I take it from what you are saying, I should go from maybe 1 turn and 2 turns on the transformer ?? What value of capacitor do you recommend if I do that ? ? Here is what I am getting now with the drive pot cut back some and either 250 or 300 ma for the bias, forgot which. ? band? power? ?Amp ( 175 ma in the receive mode) ? 80? ? ? ?16 watts? ?3.4 amps 40? ? ? ?13.5? ? ? ? ?2.7 20? ? ? ? 8.5? ? ? ? ? 2.1 15? ? ? ? 7.0? ? ? ? ? 1.5 10? ? ? ? 8.7? ? ? ? ? 1.9 ? This was with an IFR 1200s and Fluke multimeter with 13 volts measured at the power connector on the circuit board .? The power supply is an Astron 50 amp. ? Seems the efficiency is only about 35 % in rough numbers. ? I do have a very large heat sink as the ubitx just fit in an old BUD box and I had originally cut a hole in the back so the original heat sinks would fit. ? I do have a good electronic understanding in general, but not much experience with RF design.? I am more of a technician than engineer.? I bought this ubitx to play with and learn.? Thanks to Mr Farhan for the design and kit. ? Other than playing and learning with it, I plan on using it with some of the vhf/uhf converters off ebay from the Ukraine.? I have? a 2 meter one and it seems to receive very well.? Have not tested the transmit yet as I am still modifying the ubitx. ? de ku4pt ? ? ? ? On Mon, May 28, 2018 at 10:49 AM, ajparent1/KB1GMX <kb1gmx@...> wrote:
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