Date   

Re: GB3CAM

g4bao
 

The beacon keeper(s) always appreciate spots on beaconspot.uk.

Thanks to ZTR, DBN, API, GLT, XDY  for yours!

Did I miss someone? ;-)

73
John


Re: QRO capable LNA for 1296 ?

g4bao
 

Have you considered separate TX and RX feeders?
I've run like that very successfully for many years at 400W on 23cm with just a good (80db isolation) N type relay at the masthead with a DDK VLNA23 followed by a RX bandpass filter in the shack.
The RX coax can be RG58 or any old crap (even old TV coax) as the preamp has far too much gain for terrestrial use (36db) so you can afford to throw away lots of loss on RX 

73
John


Re: QRO capable LNA for 1296 ?

Neil Smith G4DBN
 

I use a Radiall like that, and an LNA isolation relay, despite the slight reduction in NF that results. I send the LNA power and relay power up separate twisted pairs in a shielded cable.  They are both fed from isolated supplies which float relative to station ground (with clamping diodes for safety). I have local filtering, spike absorbers and LDOs in the masthead box, and separate coax feeds for TX and RX. The PTT signal is optically isolated.  Some of the other masthead kit has a local PIC processor which is left in sleep mode except when it gets a command. All of the power supplies to the masthead PAs are floating at the shack end to ensure no voltages are dropped actross signal or coax shields and that transients can't get into anything.

I just hate replacing LNA front end devices. I haven't lost any since making the changes  five or six years ago.

Neil G4DBN

On 03/05/2021 16:54, Stephen Tompsett wrote:
I use a Radiall R5700 relay (500W Average Power, 80dB isolation, 0.2DB loss according to the datasheet) in my new preamp box which has been under test in the shack for some time.
I feed power to switch the relay and power the preamp via the RX cable, avoiding the need for a QRO bias tee.


Re: QRO capable LNA for 1296 ?

Stephen Tompsett
 

I use a Radiall R5700 relay (500W Average Power, 80dB isolation, 0.2DB loss according to the datasheet) in my new preamp box which has been under test in the shack for some time.
I feed power to switch the relay and power the preamp via the RX cable, avoiding the need for a QRO bias tee.

7ss Steve (G8LYB)


Re: Sabotage attempt!

Clive Elliott GW4MBS
 

With the Bengal one around, things can get even more unpredicatble when trying to load up the Land Rover.

--
Clive GW4MBS (ex-G8ADP)
Pottering on 6m - 3cm in a valley in IO71XW where any QSO is a triumph of optimism over geography!


Re: Sabotage attempt!

eightyelectric
 

Shall I bite through the red wire or the yellow wire?



Sent from my Galaxy


-------- Original message --------
From: "Clive Elliott GW4MBS via groups.io" <humber1ton@...>
Date: 03/05/2021 16:32 (GMT+00:00)
To: UKMicrowaves@groups.io
Subject: [UKMicrowaves] Sabotage attempt!

This was why I nearly didn't get on the air yesterday!

--
Clive GW4MBS (ex-G8ADP)
Pottering on 6m - 3cm in a valley in IO71XW where any QSO is a triumph of optimism over geography!


Re: 24 GHz May 2nd ?

g4bao
 

My 24GHz terrestrial system is temporarily down here, along with my other GHz Stuff.
Just waiting for a 4m 10gauge pole to arrive from metals4U then I should have 23/9/3 and 1,2cms back up a little higher at 10m AGL. That doesn't really help me to the east and NE due to trees.

Always happy to test, any mode. In the meantime you can always look for GB3CAM and GB3PKT in this direction 

My 24GHz EME system is now build and RX tested, just plucking up courage to power up the replacement TWT.
If all goes well I plan to be QRV on the next Moon cycle in a couple of weeks time.
EME is the only way I'm going to get that elusive 5th square from this QTH for the UKuG 24GHz squares award I'm chasing!  

73
John 


Re: Sabotage attempt!

Dave (G1OGY)
 

Ah!
Stroke Purrrr

Dave, G1OGY

On Mon, 3 May 2021 at 16:32, Clive Elliott GW4MBS via groups.io
<humber1ton=btinternet.com@groups.io> wrote:

This was why I nearly didn't get on the air yesterday!

--
Clive GW4MBS (ex-G8ADP)
Pottering on 6m - 3cm in a valley in IO71XW where any QSO is a triumph of optimism over geography!


Re: Sabotage attempt!

David GM6BIG
 

Hi Clive,

Almost a Cat-astrophe ?

Cheers DAvid

On 03/05/2021 16:32, Clive Elliott GW4MBS via groups.io wrote:
This was why I nearly didn't get on the air yesterday!
--
Clive GW4MBS (ex-G8ADP)
Pottering on 6m - 3cm in a valley in IO71XW where any QSO is a triumph of optimism over geography!
--
This email has been checked for viruses by Avast antivirus software.
https://www.avast.com/antivirus


Sabotage attempt!

Clive Elliott GW4MBS
 

This was why I nearly didn't get on the air yesterday!

--
Clive GW4MBS (ex-G8ADP)
Pottering on 6m - 3cm in a valley in IO71XW where any QSO is a triumph of optimism over geography!


Re: 24 GHz May 2nd ?

Dominique Dehays
 

Hi Neil and all ,


I try to avoid digital on microwaves , only SSB/CW but a good dx workhorse for 24Ghz is rain scatter , I have worked quite a number of stations in this mode. Of course never with 59s reports but once the 10Ghz report is very very strong , it is a good idea to try 24Ghz.

I had once a half qso with Maurice F6DKW at 600km via RS. It was a half one because that day Maurice was runing less power than I.Best complete qso on RS yet is 450km.

73

Dom


Re: 24 GHz May 2nd ?

Neil Smith G4DBN
 

Getting a few more 24 GHz permanent home stations active and setting up some regular MGM skeds might be fun. I've shipped out 11 sets of connector and PSU boards for the Wavelab transverters now to UK folks (and 14 to overseas stations).

I'll keep my Kuhne transverter for EME and put one of my Wavelabs on the mast with the 3cm terrestrial kit to catch any brief enhancements. I'll need to build a VLNA to get the NF low enough to get down to thermally-limited sensitivity, I'm sure.

Neil G4DBN

On 03/05/2021 12:40, John Quarmby via groups.io wrote:

Considering that the best report I gave on 10GHz over the contest period was 57, I expected nil on 24GHz. Not much local activity to draw on at present.


Re: 24 GHz May 2nd ?

John Quarmby
 

Considering that the best report I gave on 10GHz over the contest period was 57, I expected nil on 24GHz. Not much local activity to draw on at present.

73

John G3XDY

On 03/05/2021 09:16, Dominique Dehays wrote:

Hi all ,


24Ghz is a tougth band , a 59+ report on 3cm can well yield to 0 qso on 24.

73

Dom

Le 03/05/2021 à 11:05, Robin Szemeti - G1YFG a écrit :
The situation should improve ... there are a number of the Polish 2 watt systems in build ... 


On Sun, 2 May 2021 at 19:32, John Quarmby via groups.io <g3xdy=btinternet.com@groups.io> wrote:

I had 24GHz on the tower but it would be a stretch from here to IO82QL. No QSOs, one try with G4ODA right at the end (thanks Keith).

73

John G3XDY

On 02/05/2021 17:42, Martyn G3UKV wrote:
Not a single QSO on 24 GHz today from excellent site. (IO82QL83).
Tks G4OGA for try - but was there anyone else available with a sporting chance of a QSO ?
Monitored 'KST and 2 metres most of day.
73 Martyn G3UKV (as G3ZME/P)

Virus-free. www.avg.com

--
Robin Szemeti - G1YFG


Re: QRO capable LNA for 1296 ?

Mark GM4ISM
 


Ive had  preamps  damaged by  RF into the power line, in my case it was 50MHz

I now use screened power cables and  very good decoupling in the box.  Separate RX  line with an additional relay  just before it is the way to go as you suggest.

Bias Ts work well enough at high power if they are designed properly.

The highest power rating Bias T  that I have  built is theoretically OK for 1kW, I have used it  at 350W of 98MHz  and the highest temperature component inside  was running at about 40C, 'key down' for 1/2 Hour  with 2A DC.  Of course with the increased component count, internal screened compartments etc the unit is a little bigger than typical 'domestic' units.   It has more than 100dB of isolation from the RF to DC lines..   the DC cct is basically a low pass filter ( I need to pass not just DC but telemetry as well  but that's another story) 


The highest power commercial Bias T  I have used @ my QRL  is rated at 127kW mean, we run it at about 85kW at band II.  Your preamp could fit inside that coax.

Ive not looked inside. The DC blocking cap must be rather meaty.

Mark GM4ISM


On 03/05/2021 11:07, KENT BRITAIN wrote:
Hi Conrad
I have seen LNA's blown out by the Vcc wire out to the antenna.
They fire up high power on an HF band and that Vcc wire is resonate or near resonate on that HF Band.
Nearby lighting strikes are another source of high voltage on the power line to the LNA.
I highly suggest shielded wire, or a Bias T for Vcc to the LNA..       But of course the Bias T doesn't work well if 
you are also trying to put 400+ watts on that coax line! hihi

On Monday, May 3, 2021, 04:59:40 AM CDT, Conrad, PA5Y <g0ruz@...> wrote:


Well I don't agree at all with the separate DC feed, or perhaps I should say why don't you trust bias Ts? My Bias Ts have never failed. Sometimes the LNA DC choke goes O/C, this is usually because something downstream has failed.  I get a lot of summer lightning storms and feel more comfortable with the DC being inside a well screened cable. I have permanent installations and I have found better reliability using bias Tees and coax for the DC over the years and I am fairly active. Perhaps it would be a different story if all my DC cables were screened but it is far easier to have a good screen with coax. LNAs in commercial installations often use Bias Ts. 

Regards

Conrad PA5Y



From: UKMicrowaves@groups.io <UKMicrowaves@groups.io> on behalf of ian hope (2E0IJH) via groups.io <ian@...>
Sent: 03 May 2021 11:01
To: UKMicrowaves@groups.io <UKMicrowaves@groups.io>
Subject: Re: [UKMicrowaves] QRO capable LNA for 1296 ?
 
Always hardwired our LNA with seperate power feeds, never felt happy with bias T's, We use a VHF design LNA on 23, 70cm and 2m, all same setup, mast Cx600N, with sepearte TX and RX lines to transverters, only difference with the 23cm one is the PA, LNA and transverter are mast mounted.
 
Ian
M5IJH
 
 
Sent: Monday, May 03, 2021 at 9:58 AM
From: "Conrad, PA5Y" <g0ruz@...>
To: "UKMicrowaves@groups.io" <UKMicrowaves@groups.io>
Subject: Re: [UKMicrowaves] QRO capable LNA for 1296 ?
I am using exactly what you describe Tim VHF-Design LNA and a Dow Key 402A relay. I had 4 years of sterling service until Saturday morning! Now it draws no current whatsoever. It is fed via a bias T (which checks ok) up some Ultraflex 7mm coax. Of course the RX return coax could be open circuit but I doubt it very much. More likely is that DC inductor has gone open circuit, the question is why? It could range from minor to catastrophic. I will lower the mast after Tuesday's UKAC
 
Hardly a glowing recommendation but 4 years for an LNA isn't so bad. Just really bad timing!
 
73
 
Conrad PA5Y
 
 

From: UKMicrowaves@groups.io <UKMicrowaves@groups.io> on behalf of Tim, VK2XAX via groups.io <VK2XAX@...>
Sent: 03 May 2021 07:55
To: UKMicrowaves@groups.io <UKMicrowaves@groups.io>
Subject: [UKMicrowaves] QRO capable LNA for 1296 ?
 
Hi all,

just wondering what people use as a masthead LNA on 1296 that has
switching capable of handling 400w or more ?

I was thinking of building something using a VHF Designs LNA and then
wrapping it in a large transfer relay but the $ involved in doing that
may equal or exceed a ready made device given good relays can be north
of $400USD anyway.

So what are people using ?

thanks

Tim


--
VK2XAX : QF56if : ITU59 : CQ30 : BMARC : WIA






 

Virus-free. www.avg.com


10 GHz Waveguide Dummy Load

Adrian G4UVZ
 

For Sale 
High Power Wave Guide dummy load terminated in round waveguide flange 

Please PM me if of interest

Adrian


Re: QRO capable LNA for 1296 ?

Conrad, PA5Y
 

Hi Kent, no such problems here. No HF at all, perish the thought 🙂 

My experience relates to static build up during the summer, no problems with a Bias T and coax, several occasions with filtered DC cables I have had failures. I have separate RX lines on all bands and do not put any TX signals up the bias Ts.

Nearby or direct lighting strikes would without doubt wipe me out. I can't afford to do it properly. The masts are well-grounded with 4 x  1.8m long ground screws and a high water table. Nearest strike in 6 years was 2km away but it does get pretty scary quite regularly during summer.

73

Conrad PA5Y




From: UKMicrowaves@groups.io <UKMicrowaves@groups.io> on behalf of KENT BRITAIN via groups.io <WA5VJB@...>
Sent: 03 May 2021 12:07
To: UKMicrowaves@groups.io <ukmicrowaves@groups.io>; UKMicrowaves@groups.io <UKMicrowaves@groups.io>
Subject: Re: [UKMicrowaves] QRO capable LNA for 1296 ?
 
Hi Conrad
I have seen LNA's blown out by the Vcc wire out to the antenna.
They fire up high power on an HF band and that Vcc wire is resonate or near resonate on that HF Band.
Nearby lighting strikes are another source of high voltage on the power line to the LNA.
I highly suggest shielded wire, or a Bias T for Vcc to the LNA..       But of course the Bias T doesn't work well if 
you are also trying to put 400+ watts on that coax line! hihi

On Monday, May 3, 2021, 04:59:40 AM CDT, Conrad, PA5Y <g0ruz@...> wrote:


Well I don't agree at all with the separate DC feed, or perhaps I should say why don't you trust bias Ts? My Bias Ts have never failed. Sometimes the LNA DC choke goes O/C, this is usually because something downstream has failed.  I get a lot of summer lightning storms and feel more comfortable with the DC being inside a well screened cable. I have permanent installations and I have found better reliability using bias Tees and coax for the DC over the years and I am fairly active. Perhaps it would be a different story if all my DC cables were screened but it is far easier to have a good screen with coax. LNAs in commercial installations often use Bias Ts. 

Regards

Conrad PA5Y



From: UKMicrowaves@groups.io <UKMicrowaves@groups.io> on behalf of ian hope (2E0IJH) via groups.io <ian@...>
Sent: 03 May 2021 11:01
To: UKMicrowaves@groups.io <UKMicrowaves@groups.io>
Subject: Re: [UKMicrowaves] QRO capable LNA for 1296 ?
 
Always hardwired our LNA with seperate power feeds, never felt happy with bias T's, We use a VHF design LNA on 23, 70cm and 2m, all same setup, mast Cx600N, with sepearte TX and RX lines to transverters, only difference with the 23cm one is the PA, LNA and transverter are mast mounted.
 
Ian
M5IJH
 
 
Sent: Monday, May 03, 2021 at 9:58 AM
From: "Conrad, PA5Y" <g0ruz@...>
To: "UKMicrowaves@groups.io" <UKMicrowaves@groups.io>
Subject: Re: [UKMicrowaves] QRO capable LNA for 1296 ?
I am using exactly what you describe Tim VHF-Design LNA and a Dow Key 402A relay. I had 4 years of sterling service until Saturday morning! Now it draws no current whatsoever. It is fed via a bias T (which checks ok) up some Ultraflex 7mm coax. Of course the RX return coax could be open circuit but I doubt it very much. More likely is that DC inductor has gone open circuit, the question is why? It could range from minor to catastrophic. I will lower the mast after Tuesday's UKAC
 
Hardly a glowing recommendation but 4 years for an LNA isn't so bad. Just really bad timing!
 
73
 
Conrad PA5Y
 
 

From: UKMicrowaves@groups.io <UKMicrowaves@groups.io> on behalf of Tim, VK2XAX via groups.io <VK2XAX@...>
Sent: 03 May 2021 07:55
To: UKMicrowaves@groups.io <UKMicrowaves@groups.io>
Subject: [UKMicrowaves] QRO capable LNA for 1296 ?
 
Hi all,

just wondering what people use as a masthead LNA on 1296 that has
switching capable of handling 400w or more ?

I was thinking of building something using a VHF Designs LNA and then
wrapping it in a large transfer relay but the $ involved in doing that
may equal or exceed a ready made device given good relays can be north
of $400USD anyway.

So what are people using ?

thanks

Tim


--
VK2XAX : QF56if : ITU59 : CQ30 : BMARC : WIA






 


Re: QRO capable LNA for 1296 ?

KENT BRITAIN
 

Hi Conrad
I have seen LNA's blown out by the Vcc wire out to the antenna.
They fire up high power on an HF band and that Vcc wire is resonate or near resonate on that HF Band.
Nearby lighting strikes are another source of high voltage on the power line to the LNA.
I highly suggest shielded wire, or a Bias T for Vcc to the LNA..       But of course the Bias T doesn't work well if 
you are also trying to put 400+ watts on that coax line! hihi

On Monday, May 3, 2021, 04:59:40 AM CDT, Conrad, PA5Y <g0ruz@...> wrote:


Well I don't agree at all with the separate DC feed, or perhaps I should say why don't you trust bias Ts? My Bias Ts have never failed. Sometimes the LNA DC choke goes O/C, this is usually because something downstream has failed.  I get a lot of summer lightning storms and feel more comfortable with the DC being inside a well screened cable. I have permanent installations and I have found better reliability using bias Tees and coax for the DC over the years and I am fairly active. Perhaps it would be a different story if all my DC cables were screened but it is far easier to have a good screen with coax. LNAs in commercial installations often use Bias Ts. 

Regards

Conrad PA5Y



From: UKMicrowaves@groups.io <UKMicrowaves@groups.io> on behalf of ian hope (2E0IJH) via groups.io <ian@...>
Sent: 03 May 2021 11:01
To: UKMicrowaves@groups.io <UKMicrowaves@groups.io>
Subject: Re: [UKMicrowaves] QRO capable LNA for 1296 ?
 
Always hardwired our LNA with seperate power feeds, never felt happy with bias T's, We use a VHF design LNA on 23, 70cm and 2m, all same setup, mast Cx600N, with sepearte TX and RX lines to transverters, only difference with the 23cm one is the PA, LNA and transverter are mast mounted.
 
Ian
M5IJH
 
 
Sent: Monday, May 03, 2021 at 9:58 AM
From: "Conrad, PA5Y" <g0ruz@...>
To: "UKMicrowaves@groups.io" <UKMicrowaves@groups.io>
Subject: Re: [UKMicrowaves] QRO capable LNA for 1296 ?
I am using exactly what you describe Tim VHF-Design LNA and a Dow Key 402A relay. I had 4 years of sterling service until Saturday morning! Now it draws no current whatsoever. It is fed via a bias T (which checks ok) up some Ultraflex 7mm coax. Of course the RX return coax could be open circuit but I doubt it very much. More likely is that DC inductor has gone open circuit, the question is why? It could range from minor to catastrophic. I will lower the mast after Tuesday's UKAC
 
Hardly a glowing recommendation but 4 years for an LNA isn't so bad. Just really bad timing!
 
73
 
Conrad PA5Y
 
 

From: UKMicrowaves@groups.io <UKMicrowaves@groups.io> on behalf of Tim, VK2XAX via groups.io <VK2XAX@...>
Sent: 03 May 2021 07:55
To: UKMicrowaves@groups.io <UKMicrowaves@groups.io>
Subject: [UKMicrowaves] QRO capable LNA for 1296 ?
 
Hi all,

just wondering what people use as a masthead LNA on 1296 that has
switching capable of handling 400w or more ?

I was thinking of building something using a VHF Designs LNA and then
wrapping it in a large transfer relay but the $ involved in doing that
may equal or exceed a ready made device given good relays can be north
of $400USD anyway.

So what are people using ?

thanks

Tim


--
VK2XAX : QF56if : ITU59 : CQ30 : BMARC : WIA






 


Re: QRO capable LNA for 1296 ?

Conrad, PA5Y
 

Well I don't agree at all with the separate DC feed, or perhaps I should say why don't you trust bias Ts? My Bias Ts have never failed. Sometimes the LNA DC choke goes O/C, this is usually because something downstream has failed.  I get a lot of summer lightning storms and feel more comfortable with the DC being inside a well screened cable. I have permanent installations and I have found better reliability using bias Tees and coax for the DC over the years and I am fairly active. Perhaps it would be a different story if all my DC cables were screened but it is far easier to have a good screen with coax. LNAs in commercial installations often use Bias Ts. 

Regards

Conrad PA5Y



From: UKMicrowaves@groups.io <UKMicrowaves@groups.io> on behalf of ian hope (2E0IJH) via groups.io <ian@...>
Sent: 03 May 2021 11:01
To: UKMicrowaves@groups.io <UKMicrowaves@groups.io>
Subject: Re: [UKMicrowaves] QRO capable LNA for 1296 ?
 
Always hardwired our LNA with seperate power feeds, never felt happy with bias T's, We use a VHF design LNA on 23, 70cm and 2m, all same setup, mast Cx600N, with sepearte TX and RX lines to transverters, only difference with the 23cm one is the PA, LNA and transverter are mast mounted.
 
Ian
M5IJH
 
 
Sent: Monday, May 03, 2021 at 9:58 AM
From: "Conrad, PA5Y" <g0ruz@...>
To: "UKMicrowaves@groups.io" <UKMicrowaves@groups.io>
Subject: Re: [UKMicrowaves] QRO capable LNA for 1296 ?
I am using exactly what you describe Tim VHF-Design LNA and a Dow Key 402A relay. I had 4 years of sterling service until Saturday morning! Now it draws no current whatsoever. It is fed via a bias T (which checks ok) up some Ultraflex 7mm coax. Of course the RX return coax could be open circuit but I doubt it very much. More likely is that DC inductor has gone open circuit, the question is why? It could range from minor to catastrophic. I will lower the mast after Tuesday's UKAC
 
Hardly a glowing recommendation but 4 years for an LNA isn't so bad. Just really bad timing!
 
73
 
Conrad PA5Y
 
 

From: UKMicrowaves@groups.io <UKMicrowaves@groups.io> on behalf of Tim, VK2XAX via groups.io <VK2XAX@...>
Sent: 03 May 2021 07:55
To: UKMicrowaves@groups.io <UKMicrowaves@groups.io>
Subject: [UKMicrowaves] QRO capable LNA for 1296 ?
 
Hi all,

just wondering what people use as a masthead LNA on 1296 that has
switching capable of handling 400w or more ?

I was thinking of building something using a VHF Designs LNA and then
wrapping it in a large transfer relay but the $ involved in doing that
may equal or exceed a ready made device given good relays can be north
of $400USD anyway.

So what are people using ?

thanks

Tim


--
VK2XAX : QF56if : ITU59 : CQ30 : BMARC : WIA






 


Re: QRO capable LNA for 1296 ?

KENT BRITAIN
 

I am a fan of Transco 'Y's myself.
Kent

On Monday, May 3, 2021, 04:50:13 AM CDT, Conrad, PA5Y <g0ruz@...> wrote:


The Dow Key 402A definitely  does have sufficient isolation. They are excellent.

Regards

Conrad PA5Y


From: UKMicrowaves@groups.io <UKMicrowaves@groups.io> on behalf of KENT BRITAIN via groups.io <WA5VJB@...>
Sent: 03 May 2021 11:14
To: ukmicrowaves@groups.io <ukmicrowaves@groups.io>; UKMicrowaves@groups.io <UKMicrowaves@groups.io>
Subject: Re: [UKMicrowaves] QRO capable LNA for 1296 ?
 
I use two coax runs.    After the gain in the LNA, or the LNA and a buffer amp,
the loss in even RG58 on the rec side does not really add to the system Noise Figure.

Few relays have enough isolation at 23 cm to protect the preamp in the system you are considering.

So just a Single Pole, Double Throw coax relay near the feed.   And of course you can use
something bigger than RG58 on the Rec side.    A second SPDT that takes the preamp input
to a 50 Ohm load during TX is good engineering.
Kent G8EMY/WA5VJB


On Monday, May 3, 2021, 12:55:48 AM CDT, Tim, VK2XAX <vk2xax@...> wrote:


Hi all,

just wondering what people use as a masthead LNA on 1296 that has
switching capable of handling 400w or more ?

I was thinking of building something using a VHF Designs LNA and then
wrapping it in a large transfer relay but the $ involved in doing that
may equal or exceed a ready made device given good relays can be north
of $400USD anyway.

So what are people using ?

thanks

Tim


--
VK2XAX : QF56if : ITU59 : CQ30 : BMARC : WIA







Re: QRO capable LNA for 1296 ?

Conrad, PA5Y
 

The Dow Key 402A definitely  does have sufficient isolation. They are excellent.

Regards

Conrad PA5Y


From: UKMicrowaves@groups.io <UKMicrowaves@groups.io> on behalf of KENT BRITAIN via groups.io <WA5VJB@...>
Sent: 03 May 2021 11:14
To: ukmicrowaves@groups.io <ukmicrowaves@groups.io>; UKMicrowaves@groups.io <UKMicrowaves@groups.io>
Subject: Re: [UKMicrowaves] QRO capable LNA for 1296 ?
 
I use two coax runs.    After the gain in the LNA, or the LNA and a buffer amp,
the loss in even RG58 on the rec side does not really add to the system Noise Figure.

Few relays have enough isolation at 23 cm to protect the preamp in the system you are considering.

So just a Single Pole, Double Throw coax relay near the feed.   And of course you can use
something bigger than RG58 on the Rec side.    A second SPDT that takes the preamp input
to a 50 Ohm load during TX is good engineering.
Kent G8EMY/WA5VJB


On Monday, May 3, 2021, 12:55:48 AM CDT, Tim, VK2XAX <vk2xax@...> wrote:


Hi all,

just wondering what people use as a masthead LNA on 1296 that has
switching capable of handling 400w or more ?

I was thinking of building something using a VHF Designs LNA and then
wrapping it in a large transfer relay but the $ involved in doing that
may equal or exceed a ready made device given good relays can be north
of $400USD anyway.

So what are people using ?

thanks

Tim


--
VK2XAX : QF56if : ITU59 : CQ30 : BMARC : WIA






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